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J Tiers
02-06-2008, 09:12 PM
Got several 2MT "blank arbors" for making tailstock tooling, since I was lazy enough to not want to set up for tapers and cut them all, etc, etc.....

Well, the arbors that came in are from "India", and NO they do NOT "blue up" right.....

I checked with a Bison live center, and of course IT has essentially full contact everywhere.

The arbors have good contact at the large end, and barely touched at any point at the small end.

Yah..... you get what you pay for...... maybe. In this case, I bought the only type available from the vendor, so no I didn't bottom-feed.

Just venting....... grumpy because I'll have to set up after all and grind these true if I want arbors any time soon.

Oldguy
02-06-2008, 09:29 PM
Have to agree with you. I bought couple of MT adapters from a vendor and they were a mixed lot. One was from Poland and was very nicely finished, even in the areas that weren't critical to its use. The one from India was okay where it needed to be and the rest looked like junk. In general, if it says made in India I'll pass.

Glenn

drof34
02-06-2008, 11:37 PM
What do you do when you go buy a new 50HP tractor(model 5301) from you local John Deere dealer and you find out it was made in India? When the salesman was asked about this, his reply was that it was probably more American than most of their tractors, except for their hugh ones.

A few years back Cadillac had a TV commercial claiming their cars were assembled from world class parts.

Jim W.

J Tiers
02-07-2008, 12:27 AM
In this case, it isn't so much about country of origin, it is about the obvious fact that the folks over there DO NOT KNOW what a 2MT IS.................

Angles and grinders don't know from nations........

The finish is very good, the grinding is FIRST CLASS.

But the ^%$#(*&!! ANGLE is WRONG.

All I can figure is that this is "the nearest metric equivalent"............ :rolleyes:

JRouche
02-07-2008, 01:14 AM
In this case, it isn't so much about country of origin,

If you say so. I have never bought any tooling "from" India that was worth the shipping. Either the metal used was a mix-mash of crap and of a poor finish or the dims were way off. Sounds like yer case was the dims. Quality control must have been over looked at that shop..

And I dont even wanna say I am bashing the abilities of Indian tool makers. Just the same with Chinese tooling.

The countries as a whole have the ability to produce exacting tolerance tooling. After all, they are both nuclear capable nations.

Guess it really does come down to "you get what you pay for". Given a higher budget (income) those manufactures could prolly give you exactly what you want.. The short buck usually produces the shorter quality.. In yer case, unusable. JRouche

Evan
02-07-2008, 07:44 AM
Groz products are made in India. I have two Groz vises and they are both well made and well finished. They were very reasonably priced and do the job nicely.

J Tiers
02-07-2008, 07:45 AM
And I dont even wanna say I am bashing the abilities of Indian tool makers. Just the same with Chinese tooling.

The countries as a whole have the ability to produce exacting tolerance tooling. After all, they are both nuclear capable nations.

Guess it really does come down to "you get what you pay for".

I think I did address those issues............ ;)


Yah..... you get what you pay for...... maybe. In this case, I bought the only type available from the vendor, so no I didn't bottom-feed.


The finish is very good, the grinding is FIRST CLASS.

But the ^%$#(*&!! ANGLE is WRONG.

No, it isn't a LOT wrong, and no, I can't actually feel it move. But it won't rub off a black marker stripe all the way down, but a Bison center DOES rub off everywhere.

I know the T/S is right, as I had recently to do a clean-up ream on it, and I used a "Morse" brand made-in-USA reamer to do the job (with location via the H/S). I suspect that was correct, particularly because that well-made center is a perfect fit.

BTW, India has come a long way in exports. I bought, for quite a substantial $$, a threaded chuck arbor several years ago. I was VERY annoyed to note it came from India, and appeared to have been chewed to shape out of rebar by a drunk squirrel. J&L got it back right away.

These things are for all intents and purposes equal to Bison, EXCEPT that the wrong gage was used to check it.

Milacron of PM
02-07-2008, 09:12 AM
Groz products are made in India. I have two Groz vises and they are both well made and well finished. They were very reasonably priced and do the job nicely. When I manufactured tapping machines, I bought hundreds of Bilz type quick change adapters from Centaur, which is an Indian company. I also offered Bilz, Emuge and Tapmatic versions but eventually went almost entirely with Centaur as we never had a single quality issue and never any complaints from customers with their tools.

So, bottom line...just because it comes from India doesn't make it bad....but if the price is extremely low and from India...look out...

http://www.centaurtools.com/products/tapping/tapping.asp

TGTool
02-07-2008, 11:01 AM
I got a #2 Morse chuck adapter a couple years ago with a problem on the Morse taper. In this case it was clear that the taper had been ground with a form wheel in two steps and the infeed didn't match. That is, there were essentially two short tapers with a small bump at the juncture. I don't remember if it indicated where it was made. I complained to J&L who cheerfully refunded that one and I bought a Jacobs for a little more money.

It was interesting to me that they would use that particular process. It would be fast production, but really prone to error because the machine makes two moves, one longitudinal and one infeed that both have to be absolutely right or the taper doesn't match up as this one showed. Plus you've got the angle dressing of the wheel! Under NC I might be more prone to trust it, but for manually run production swinging the table for the taper would ensure that once checked it would be trustworthy throughout the run. Even a little corner breakdown on the wheel wouldn't hurt you so long as you could overtravel a little on each end.

JCHannum
02-07-2008, 11:21 AM
Quite a few MT adaptors are ground with a relieved portion in the center to eliminate the step situation as well as reduce the amount to be removed by grinding.

The first question would be "Is the taper in tolerance?" It appears it might well be;

http://www.practicalmachinist.com/vb/showthread.php?t=151534

It is more than possible that both the TS and adaptor are in spec, but simply on different ends of it. The MT spec is pretty loose.

lazlo
02-07-2008, 06:49 PM
So, bottom line...just because it comes from India doesn't make it bad....but if the price is extremely low and from India...look out...

I just bought a Hertel ER-40, 50 Taper collet chuck from J&L industrial. I was suspicious of the country of origin, because the 50 taper adapter (which probably weighs 20 lbs) was a lot cheaper than the ETM ER-40, MT3 collet chuck I bought in the same order.

I was seriously annoyed when the Hertel collet chuck showed up, and it was clearly marked Made in India.

However, I was equally surprised, when I opened the box, at the excellent fit and finish of the part. I ran out to the shop and blued it against my T&C grinder workhead, and it's a perfect fit.

I was truly impressed. My experience with Indian tools up this point was the same as J Tiers.

But like JRouche says, it probably has a lot to do with how much the vendor is willing to pay for the item. If you pay them dirt, you're probably going to get a sh!tty product. If you pay them well, hopefully you have a better chance at getting a good product.

J Tiers
02-07-2008, 07:08 PM
Quite a few MT adaptors are ground with a relieved portion in the center to eliminate the step situation as well as reduce the amount to be removed by grinding.

The first question would be "Is the taper in tolerance?" It appears it might well be;

http://www.practicalmachinist.com/vb/showthread.php?t=151534

It is more than possible that both the TS and adaptor are in spec, but simply on different ends of it. The MT spec is pretty loose.

For an MT2 it's around 0.0004 total along the taper.

Dunno how important that would be for drill tooling.

lazlo
02-07-2008, 07:14 PM
It is more than possible that both the TS and adaptor are in spec, but simply on different ends of it. The MT spec is pretty loose.

I don't understand that comment JC -- the Morse Taper spec is .7" large end, .572" small end, 2.562" length, and a taper of 0.04995" per foot. That doesn't seem very loose!

http://www.gizmology.net/tapers.htm

JCHannum
02-07-2008, 07:54 PM
Jerry quotes a number of 0.0004" over the length of the taper. +- 0.0004" can add to 0.0008". What is the thickness of a magic marker mark?

Morse couldn't even get it right. They were trying for 5/8"/foot, but did not hit it on any of the tapers due to difficulty in making accurate gaging. None of the tapers agrees with any of the others.

lazlo
02-07-2008, 08:06 PM
Jerry quotes a number of 0.0004" over the length of the taper. +- 0.0004" can add to 0.0008". What is the thickness of a magic marker mark?

Yeah, that's surprising to me too. Doesn't seem like the taper would wring if it's off by 8 tenths in 2.6". Is the tolerance +/- 4 thou per foot, or 4 thou per foot (+/- 2 thou)?


Morse couldn't even get it right. They were trying for 5/8"/foot, but did not hit it on any of the tapers due to difficulty in making accurate gaging. None of the tapers agrees with any of the others.

None of the "Old School" tapers (Morse, Brown & Sharpe, Jacobs) have a consistent taper per foot, with the notable exception of Jarno, which no one used :)

I never did understand why that was...

I wonder about the taper gauge explanation -- the Advanced Machine Work book that JT has been recommending shows, step-by-step, how turn of the century toolmakers lapped taper and plug gages to tenths accuracy... The way it's documented in AMW, it doesn't seem like those accuracies were exceptional.

JCHannum
02-07-2008, 08:26 PM
That is an interesting question. It is likely that they did lap to tenths accuracy, but probably to "their" tenths, each shop having their own set of standards that were different from their neighbors'.

It was not until the advent of Jo Blocks in the thirties that there was a convenient way to compare between shops. Henry Ford was quick to recognise the value of this and jumped on them like a duck on a june bug.

J Tiers
02-07-2008, 09:26 PM
According to my Machinery's Handbook, the tolerance is:

0.002 inches per foot.

The notes state that the tolerance HAS to be such that a shank is wider than standard at the wide end, or a socket is narrower at the wide end. That makes it always tight at the wide end. (and makes it one-sided).

That puts it at 0.0005 per 3", or around 4 tenths for an MT2, 5 tenths or so for an MT3, given a perfect socket.

The TOTAL possible is the sum of the two, or 0.004 tighter at the wide end, and 0.001 clearance in 3" at the small end.

As far as I know, there should be some "damage" to a marker ink stripe with only 4 tenths clearance.......on one side or another. Marker ink is a thicker coating than the typical thickness of "blue".

Barring a co-incidence, I suspect the reamer (and now the socket) is correct at nominal taper within close limits, since it mates perfectly with a product from another country that was made at a different time. Presumably both were aiming at the "dead-on" setting.

Therefore, another piece which does not even "slightly damage" a thick coating of marker ink at one end, must be presumed to have an error of taper that is larger than the allowable error of 0.002 per foot, unidirectional.

And, indeed, the error is in the correct direction. just probably too large.

I could probably figure out a practical way to measure it, starting with reversing the two tapers in contact with each other and measuring across them.

J.Ramsey
02-08-2008, 06:57 AM
Unless you have a "toolroom" quality lathe stick in the hole and forget about it.
The tailstock alignment or its barrel travel is more than likely out more than that.

J Tiers
02-08-2008, 08:12 AM
Unless you have a "toolroom" quality lathe stick in the hole and forget about it.
The tailstock alignment or its barrel travel is more than likely out more than that.

ASTOUNDING that you would make a blanket statement like that......... You have no idea exactly what I am intending to use these for.

The problem OBVIOUSLY is not the slight error of position, but rather the looseness and the degree to which the taper will reliably HOLD.

A loose taper will rapidly work it's way out, and even drilling produces side forces.

Not ONLY that, but any tool that produces ANY pull-out force on the taper is EXTREMELY dependent on a good fit so that it does not simply flop out of the taper. A drill produces a pull-out force, at least when withdrawn from the work.

Milacron of PM
02-08-2008, 10:14 AM
ASTOUNDING that you would make a blanket statement like that......... You have no idea exactly what I am intending to use these for.

LOL... I never ceased to be amazed at the conclusions folks jump to on internet forums... I guess many fancy themselves as Sherlock Holmes and just can't resist showing how "smart" they are... ;)

J.Ramsey
02-08-2008, 10:56 AM
"I got several 2MT blank arbors"
Those are the first five words in this thread, so machine them for a tang drive and forget about it.

I myself would be to embarrassed to complain about an el cheapo part on www.

Milacron,..........oops I meant Sherlock
You jump to plenty of conclusions yourself.

lazlo
02-08-2008, 11:01 AM
Unless you have a "toolroom" quality lathe stick in the hole and forget about it. The tailstock alignment or its barrel travel is more than likely out more than that.

JT's talking about it having the wrong taper, which means it won't stay in the tailstock.

By the way Jerry, have you measured the shank for runout? If they botched the taper grind, there's a good chance the concentricity isn't good either...

Your post had me worried last night because I bought several of those cheap Indian MT3 blanks from KBC Tools. I've already been using one, and that one is fine (doesn't wobble or spin in my tailstock). I just took the remaining two out of their boxes, and they blue-up nicely in my tailstock. They grind them a bit long so you have some meat before the blank abor piece, so you can't really measure the gage line, but a quick measurement on the small end reads .7795 (.778 is the MT3 spec). That's a close as I can measure without cobbling a taper jig.

By the way, my MT3 blank arbors are in yellow/blue boxes marked "Bayard Industrial."

Edit: these Indian MT blanks are really home-shop grade arbors. If you want a professional quality Morse Taper blank, you might consider the Collis blank arbors, but they're $45 each. MSC and KBC carries them. I think Enco used to as well...

J.Ramsey
02-08-2008, 11:11 AM
JT's talking about it having the wrong taper, which means it won't stay in the tailstock.

By the way Jerry, have you measured the shank for runout? If they botched the taper grind, there's a good chance the concentricity isn't good either...

Your post had me worried last night because I bought several of those cheap Indian MT3 blanks from KBC Tools. I've already been using one, and that one is fine (doesn't wobble or spin in my tailstock). I just took the remaining two out of their boxes, and they blue-up nicely in my tailstock. They grind them a bit long so you have some meat before the blank abor piece, so you can't really measure the gage line, but a quick measurement on the small end reads .7795 (.778 is the MT3 spec). That's a close as I can measure without cobbling a taper jig.

By the way, my MT3 blank arbors are in yellow/blue boxes marked "Bayard Industrial."

Edit: these Indian MT blanks are really home-shop grade arbors. If you want a professional quality Morse Taper blank, you might consider the Collis blank arbors, but they're $45 each. MSC and KBC carries them. I think Enco used to as well...

Yea I guess I did just fall off the turnip truck.

lazlo
02-08-2008, 11:16 AM
Yea I guess I did just fall off the turnip truck.

I don't understand your point J.

You told JTiers to just ignore the runout and use the morse arbor as-is. He hasn't even measured the runout: he can't get the abor to stay in the tailstock, because they ground the taper too shallow.

J.Ramsey
02-08-2008, 01:02 PM
I don't understand your point J.

You told JTiers to just ignore the runout and use the morse arbor as-is. He hasn't even measured the runout: he can't get the abor to stay in the tailstock, because they ground the taper too shallow.

I never said anything about runout.
The OP started this thread as a rant about getting cheap tooling thats not up to spec.
You get what you pay for.
JST has a thread on the PM site about Morse tapers but its not a rant because he knows ranting or talking about cheap tools isn't tolerated on that forum. Lockie poo as Milacron puts it.
22 replies here 2 over there.
It amazes me that people EXPECT high quality for a cheap price and then they b!tch when the piece doesn't meet their expectations or specifications .
I would send them back if I didn't want to repair them.

dan s
02-08-2008, 03:59 PM
I never said anything about runout.
The OP started this thread as a rant about getting cheap tooling thats not up to spec.
You get what you pay for.
JST has a thread on the PM site about Morse tapers but its not a rant because he knows ranting or talking about cheap tools isn't tolerated on that forum. Lockie poo as Milacron puts it.
22 replies here 2 over there.
It amazes me that people EXPECT high quality for a cheap price and then they b!tch when the piece doesn't meet their expectations or specifications .
I would send them back if I didn't want to repair them.

F that.... there is a big difference between a tool being cheap and being so out of spec, that i can't be used. J didn't say he expected anything, but i would wager he was at least expecting the blanks to be serviceable.

It amazes me how many people automatically assume cheap means poor quality, and expensive means high quality.

sconisbee
02-08-2008, 04:13 PM
It amazes me how many people automatically assume cheap means poor quality, and expensive means high quality.

I'll agree with that, whilst i dont want to get into an argument, i have however done alot of work recently on a so called "Super Yacht" worth $4.5 million USD, all top dollar high end work and there is a shed load of poor craftmanship and quality work on her especially in regards to her precision parts.... Likewise i have worked on some "cheap" equipment that has been very well made. And if the company sold JTiers blanks that were sold as Morse Taper then that assumes no matter how badly made that they are in spec, afterall thats why the specifications were set out for int he firstplace.

lazlo
02-08-2008, 04:19 PM
It amazes me how many people automatically assume cheap means poor quality, and expensive means high quality.

JTier's original point, echoed by J. Ramsey and Don, and me :p is that you get what you pay for:


Yah..... you get what you pay for......

So, bottom line...just because it comes from India doesn't make it bad....but if the price is extremely low and from India...look out...

The Indian 3MT blank arbor is $7.60 at KBC, and the Collis 3MT blank is $48.90 at KBC. Which one do you think is more likely to meet spec? :)

3MT BLANK END DRILL CHUCK ARBOR
http://www.kbctools.com/usa/Navigation/NavPDF.cfm?PDFPage=403

3MT COLLIS BLANK END ARBOR (1.3/4 BODY DIAMETER)
http://www.kbctools.com/usa/Navigation/NavPDF.cfm?PDFPage=406

So yes, in general, if I'm buying a cheap tool, I assume it's poor quality, and sometimes I'm pleasantly surprised. Most times I'm not.

Ironically, about a year ago JTiers bought a Chinese endmill holder, and was pissed that it wasn't concentric, the drawbar threads were out of spec,... He complained to the vendor and they replaced it with a Bison ;)

Milacron of PM
02-08-2008, 07:02 PM
I'll agree with that, whilst i dont want to get into an argument, i have however done alot of work recently on a so called "Super Yacht" worth $4.5 million USD, all top dollar high end work and there is a shed load of poor craftmanship and quality work on her especially in regards to her precision parts.... Likewise i have worked on some "cheap" equipment that has been very well made. And if the company sold JTiers blanks that were sold as Morse Taper then that assumes no matter how badly made that they are in spec, afterall thats why the specifications were set out for int he firstplace.

1. A yacht is a poor analogy to what we are talking about here. Multimillion dollar yachts are typically built one at a time, have extremely complex systems, and subject to harsh conditions and varied failures, esp when new. It's my impression from talking with delivery captains that most high dollar yachts have such complex systems these days that numerous failures are to be expected during the first few months, no matter who made the boat or how much it cost. But I suspect a cheap yacht, like a Bayliner 45, would have even more failures.

2. I doubt anyone here is assuming cheap always means "bad" and expensive always means "good" But the probabilities of higher quality are in the expensive camp's favor and probabities of poor quality in the cheap camp's favor. All about probabilities.

J Tiers
02-08-2008, 08:02 PM
The OP started this thread as a rant about getting cheap tooling thats not up to spec.
You get what you pay for.

Sometimes you do, sometimes you don't..... Sometimes the high price just lets you rest assured that money bought you the most expensive brand label available. The fact that a 50 cent label may be all that distinguishes it from any other item of its type is something that rich yuppies don't want to hear.

The PM thread is a direct question concerning the larger-than-I-expected spec tolerance on MT tooling, and what it really means to usage. I didn't edit because of PM, I asked, and expected I might get an intelligent answer to, a technical question over there. Lots of knowledgeable folks there.

But the POINT is NOT a "rant" about cheap tooling......although I did mention "venting". If it was crappily made, I'd be actually less annoyed......

These are VERY WELL MADE. There is nothing to complain about as to finish..... fit is another thing entirely.

The ironic things are:

1) The one thing wrong with them WOULD HAVE COST NOTHING TO GET RIGHT.... just set the dial differently.

2) I bought the most expensive ones listed in the catalog.

3) They don't "fall out of the taper", quite...... They are "close" to being OK, but just far enough "out" that you don't feel justified in spending a lot of time making a tool out of one....
They appear to be out of spec, but I don't have a gage line reference and so would have to work to check them..... sine plate, gage blocks, 0.0001 indicator, some form of holder to hold them straight........ seems like too much work, when a simple comparison of "bluing up" seems to tell the story.

I really need a taper gage, but they are a tad expensive....... I could always make one...... at least then I could do a legitimate comparison.




JTier's original point, echoed by J. Ramsey and Don, and me :p is that you get what you pay for:

Ironically, about a year ago JTiers bought a Chinese endmill holder, and was pissed that it wasn't concentric, the drawbar threads were out of spec,... He complained to the vendor and they replaced it with a Bison ;)

Not quite.........

I bought, for what appeared to be a regular Bison type price, what I EXPECTED to be a Bison part. I had bought Bison before from same vendor, and was happy to pay the Bison price. It wasn't a $5 holder........ more like a $35 holder, maybe $40, don't recall.

Instead I got a cheezy item from china WITH THE WRONG DRAWBAR TAPER, NOT PER CATALOG DESCRIPTION. I have NO IDEA if it was concentric, as far as I recall I never measured it. Could be wrong, I seem to recall a discussion of concentricity, but I think that was a different thread, and I measured a Bison part..

I told the folks at the distributor that I wanted Bison and would be happy to pay for it. They gave me the Bison at the original price, instead of charging the difference. I was willing to pay the difference, I don't like junk.

So watch out for your inferences there, big guy, don't assume I am a cheap HF junkie who wants Collis etc quality for a flung dung price.....


By the way Jerry, have you measured the shank for runout? If they botched the taper grind, there's a good chance the concentricity isn't good either...

Dunno, would have to measure between centers, since there isn't any finish machined feature except the centers and taper.... this isn't a holder, but a "blank arbor", which you are expected to machine the business end of to your spec and needs.

I don't have an MT2 native spindle, only a T/S. So I'd have to use an adapter, and wouldn't know who was wrong without even more hassle.


BTW... What was that thing about a "tang drive"???? Means what?

wirewrkr
02-08-2008, 08:48 PM
Good timing on this post as I'm just getting ready to buy a new TS arbor for an Allbrecht chuck someone just "gifted" me. since it was free, I should probably opt for a better quality arbor. Jacobs or Bison. My Bison 5' inch 3 jaw chuck is the only one of the three I've bought that spin true right out of the box.
Robert

JCHannum
02-08-2008, 09:15 PM
The justification for complaint is questionable since the actual dimensions of the taper blanks is not known. It is assumed they are wrong because they are made in India. It is assumed the tailstock is right because it was reamed with a reamer that is assumed to be correct because it was made by Morse. It is assumed the live center used to check the TS was right because it was made in Poland. That is a lot of assuming, why can it not also be assumed they are all within specification.

Unless actual dimensions assigned, whether they are in tolerance or not will never be known.

Without knowing the intended application, whether a problem exists or not also cannot be determined. Since the original design of the MT shank was for drilling, pressure of the drilling operation will tend to make it tighter in the socket. In that instance, the adaptors will probably work if they are within tolerance.

The MT was not designed to handle side forces or pullout forces. If the application will be subject to these forces a different arrangement should be considered. MT arbors subject to these forces are threaded for drawbars.

lazlo
02-08-2008, 09:38 PM
,I should probably opt for a better quality arbor. Jacobs or Bison.

I've had good luck with Bison, but be careful with Jacobs -- they were bought out by the Danaher group years ago, and a lot of their stuff is now made in China.

I have several Collis abors, adapters, and although they're expensive, they're exceptionally well-made.

J.Ramsey
02-08-2008, 09:42 PM
BTW... What was that thing about a "tang drive"???? Means what?

It's the fat little blade or tang on the arbor end of a MT drill or adapter that fits the corresponding slot in the quill that keeps it from turning/slipping in the taper when under a high torque load that the fit of the taper can't hold by it self.
Most smaller lathes don't have this feature,usually MT3 and up have it .

J Tiers
02-08-2008, 11:30 PM
It's the fat little blade or tang on the arbor end of a MT drill or adapter that fits the corresponding slot in the quill that keeps it from turning/slipping in the taper when under a high torque load that the fit of the taper can't hold by it self.
Most smaller lathes don't have this feature,usually MT3 and up have it .

Odd, If THAT was all you meant...... they already have the "removal tang" on them. As far as that being a "driving tang", well the ones I've seen twisted off didn't drive very well. The friction of a taper socket drives very well indeed, I doubt the tang adds anything, and I have heard the "driving tang" theory disputed by persons such as Forrest A.


That is a lot of assuming, why can it not also be assumed they are all within specification. The evidence is that they appear to be "out", but they might possibly be just at the limit.... As for the reamer and center.... If three things are INTENDED to be made to fit into identical recesses tightly, and TWO of them precisely fit a particular recess, the simplest "assumption" is that both are very closely correct, and the odd one out is wrong.
Otherwise, you have to assume that the two totally independently made items that fit well are both "off" to the precisely identical amount.......and I suggest THAT is a LOT of assumption.


The MT was not designed to handle side forces or pullout forces. If the application will be subject to these forces a different arrangement should be considered. MT arbors subject to these forces are threaded for drawbars.

I didn't just hatch this morning........ I do know that. The amount of side force or end force I expect is the same that a drill would experience. And that can be substantial, due to chips, but drills don't have drawbars.

A good fit of taper ejects with somewhat of a "pop", it does not just "flop" out of the taper. Therefore it can withstand some end force, but clearly not a lot, a drawbar is required to resist substantial pulls, or milling. But a Morse is not a "self-ejecting" taper, rather it is more-or-less a "self-locking" taper.

And, it is a rare tail-stock which has provision for a draw-bar, although I understand they do exist.

J.Ramsey
02-09-2008, 01:14 AM
JT
You sound like some people I know that even though they're not always right they're never wrong.
Who's Forrest A. ? Did he design the Morse taper?
If the tang is for removal then why the 2 flats?
I have Greenfield 3-1/4 # 5 Morse taper drill bit that gets used often in an old 32" Hamilton lathe and I seriously doubt the taper alone would hold it even if I drove it in the tailstock quill with a 20 lb. sledge hammer.
I'm sure you own a drill press?
Knock out the Morse taper arbor an then try to reinstall it with the tang 90 degrees to the key removal slot ................ bet it won't fit.
Better yet saw off your so called removal tang and see how long till it slips and falls out of the quill.
I think you would complain to the hangman even if he used a new rope.

J Tiers
02-09-2008, 01:31 AM
Forrest Addy is a guy who has been in the biz for a long time and probably knows more about machine work than both of us put together.

He is also the guy who does the scraping seminars that were organized by folks over on PM.... And the professionals over there respect his opinion a lot. I share that opinion of him. He has written a number of excellent articles for the magazine that sponsors this very site.

In any case, I have a drill or so with bad (missing) tang, and they seem to drill just as well as any other, don't slip, but I DO have to tap them in solidly.

if you have ever had to get a morse taper collet out after it's been rammed in well by holding work or a tool, you'd agree with the 'self-locking" description.

And, I notice that drills which have been "pressured through" the work definitely come out with a "pop". There is a REASON why those wedges have to be tapped on smartly to get the drill out of the spindle.

Of course it won't even go into the socket at 90 deg, unless it is one of the ones that were made with a round "nub" and not a tang. Yes there were some, no doubt to stop folks depending on the tang for driving......... I think I have one somewhere.

"One of those guys who is never wrong"?

That's a good, workable, insult, (and also an "ad hominem abusive" argument, btw) intended to end an argument on a "winning note" for the accuser, but t'aint so.

I was wrong once in 1987, and I don't mind admitting it. So there! :D

J.Ramsey
02-09-2008, 02:08 AM
I guess that was you and Forrest driving the turnip truck I fell out of but I didn't realize that back in 1987.

You know you've spent more time talking/typing about your taper problem then it should have taken to fix it in the first place.

Professional?
Most machinist I know consider themselves tradesmen/craftsmen unless they have a chip on their shoulder.

JCHannum
02-09-2008, 08:11 AM
Regardless of what you assume, without numbers, all you know is that you have some taper shanks that are different. Reaming of the tailstock is not a precise operation, reamers will follow an out of line hole, and if not precisely in line, a taper reamer can produce a hole that is large on the small end.

Forrest is a great guy, but subject as subject to presenting opinion as fact as anyone else. I have a 1972 Bendix Tools catalog that defines tang as " The flattened end of a taper shank, intended to fit into a driving slot in a socket.

Armstrong, Williams and probably others manufactured taper shank sleeves with handles to be used in lathe tailstocks to keep taper shank tooling from slipping in a tailstock not equipped with a driving slot.

sconisbee
02-09-2008, 10:03 AM
1. A yacht is a poor analogy to what we are talking about here....

2. I doubt anyone here is assuming cheap always means "bad" and expensive always means "good" ...

Granted, wasnt the best analogy, but is what came to mind, that and what i guess i didnt make clear was i was refering to some of the more critical subsystems that are made to similar spec limits to MT tapers, including some components critical to operation.

its not so much that they have failed "yet" its more that on some of the parts ive worked on are produciton parts used on almost all of the yachts made by the shipyard that made this one (which is since operating under a different name by a different company) most of the problems come down to the hydraulic systems where even the spares supplied from the original company were out of spec, and they were 280 spares for something around about the size of a cellphone. the yacht is far from new and the out of spec parts have lasted and have been fine for the intended use but if their had been a faliure at sea then the spares wouldnt have fitted and would have left the yacht stranded.

But enough of that as i said i didnt want to argue:D anyway my point was more along the lines of while most of the time you do get what you pay for and was pretty much agreeing with you and JT and lazlo.

But my main thought is/was sometimes albeit rarely you do get bad products from both ends of the expense scale and that if something is sold as an item that would normally be universaly expected to be within limits then i would expect even a cheap tool/taper to be within said limits regardless of price or origin. I've had bad sandvik tapers and bad cheap ones both of which were replaced for accurate stock.

With that said im also guilty of buying the cheap option if its not going to get much use.

I suppose its possible they had fill in workers or a trainee that day on QM so the bad tapers slipped through, which is pretty much what happend with my sandvik stuff which they replaced with absolutly no trouble at all.

lazlo
02-09-2008, 10:11 AM
It's the fat little blade or tang on the arbor end of a MT drill or adapter that fits the corresponding slot in the quill that keeps it from turning/slipping in the taper when under a high torque load that the fit of the taper can't hold by it self.

My Clausing tailstock (MT3) has the driving slot to keep the taper from spinning. The Monarch's do as well.

Milacron of PM
02-09-2008, 10:20 AM
You know you've spent more time talking/typing about your taper problem then it should have taken to fix it in the first place.

Ironic statement considering YOU are a major contributor to JT's "excess" talking/typing.

Amazes me when that happens on forums....the original poster gets the answers he needs in the first two or three responses and it would end there. But then other folks keep chattering away, often with total irrelevant BS of speculation or that accuses the poster of this or that. So the poster continues on just to clarify matters or defend himself from the BS.

And then the very BS perpetrator that contributed to the poster having to type unnecessarily more, is the very one who then makes fun of the poster for spending too much time typing about it !

J Tiers
02-09-2008, 10:57 AM
Considering that "fixing it" involves tools I do not actually own (universal grinder, mine is incomplete) and do not have handy access to, don't know about "less time to fix". I might get it done in a week or two if I make arrangements. If I had to I could get it faster.

Are they out of spec?

I DO NOT GIVE A RAT'S TUSCHIE IF THEY ARE OUT OF SPEC OR IN SPEC.

They do not fit well enough to work for the application, and yes indeedy, they DO "FLOP OUT" of the taper, when a large selection of other taper shank tools STAY IN and come out with a "pop".

1) Specs are written originally by the developer of the "device", and "groomed" by industry folks who don't want extra production trouble. 0.002 per foot probably makes a nearly unusable fit if BOTH the taper and the tool are at maximum error. That would be 0.004 per foot loose, and the taper might well not hold. But it surely makes it easy to make..... with tools per 1870 or so.

2) Very odd that my "must be out of spec and obviously isn't accurate because it is reamed and not ground" taper just HAPPENS to FIT a wide variety of tools that were made at different times by different folks and therefore have totally uncorrelated errors.

It is obviously technically not "impossible" that all my other MT2 shank tools AND the reamer are miles out of spec in the same direction. But it isn't very likely.

Do I KNOW what the actual error of the tapers is? NOPE...... and I never have claimed to *KNOW*.

For all I know, that is what a "limit spec" MT is like. I'll have to measure their taper, that does not require any gage-line info, just a slope. Sounds like a pain.

What I know is that these three, from a suspect source, are DIFFERENT from that "boxload" of ones made by generally respected companies like Morse, Cleveland T & D, Jacobs (old Jacobs) etc, and even Bison brand. I also know these three are different enough to be unusable in general.

Given that, apparently the ONLY possible assumption is that these three are the ONLY ones of the lot that are "in spec"...... YUP, that's what anyone would deduce from the info at hand. Uh HUH....!

Heck, the original point was that these things are so well finished, and nice looking, you'd a thunk the makers would have bothered to get the taper close enough to work right.

BTW, I type fairly fast, so no need to feel I am wasting time.......

Evan
02-09-2008, 11:36 AM
Knock out the Morse taper arbor an then try to reinstall it with the tang 90 degrees to the key removal slot ................ bet it won't fit.
Better yet saw off your so called removal tang and see how long till it slips and falls out of the quill.

The tang is for removal. It's not hardened and will twist if allowed to take torque loads because of a poor fit of the taper in the socket. The reason it is made as a flat tang is to prevent spinning of the taper in case of looseness so that the spindle isn't damaged by such spinning, not to provide drive. It's a safety feature as well as a removal feature. It's better to damage the drill bit than the spindle.

The tailstock and headstock on my South bend have no provision for trapping the tang and yet have no trouble drilling 1" holes in steel. I have perhaps 25 or so MT2 and MT3 drill bits. They are either US or UK made and never slip unless I haven't cleaned something properly.

J Tiers
02-09-2008, 04:49 PM
OK, they ARE out of spec.............

Large end = 0.7148

small end = 0.5764

distance along taper slope is 2.741"

Doing the appropriate trig to get the actual length on axis, and figurung out teh taper, I get an actual taper per foot of 0.6066.

The spec taper is 0.5994

That would appear to put these at nearly 3 X the tolerance out of spec

J.Ramsey
02-10-2008, 03:21 AM
Ironic statement considering YOU are a major contributor to JT's "excess" talking/typing.

Amazes me when that happens on forums....the original poster gets the answers he needs in the first two or three responses and it would end there. But then other folks keep chattering away, often with total irrelevant BS of speculation or that accuses the poster of this or that. So the poster continues on just to clarify matters or defend himself from the BS.

And then the very BS perpetrator that contributed to the poster having to type unnecessarily more, is the very one who then makes fun of the poster for spending too much time typing about it !

But not ironic of you to criticize those who don't agree with you or your butt kissin' cronies..... thats well known.

Countless times you yourself have asked questions on your own PM forum and
received good answers for the amount of info you provided but you bashed or belittled the poster because they don't have the ability to read your mind.

JCHannum
02-10-2008, 08:36 AM
OK, they ARE out of spec.............

Large end = 0.7148

small end = 0.5764

OK, now you are assigning dimensions to the taper. I find it difficult to measure tapers with common HSM equipment, and by your reply on the PM thread, apparently you do too;

"Well, I simplified the measurement, to get a "close rough estimate", and found that if a taper is way out of spec, it won't fit well..... Kind of obvious, I guess....... "

We have gone from an assumption to a "close rough estimate". However close and fourth place readings are kind of oxymoronic. It is extremely difficult to measure a taper, accurately locate the points where the two measurements were made, and then measure the distance between. What is the taper of the Bison center using this same "close rough estimate" method?

I do find it more meaningful when actual information is presented rather than a rant because something does not meet with someone's approval.

As far as the function of the tang on Morse Taper tooling, so far, I have three references that attest to the fact that it is used to drive the drill. The taper handles a portion and the tang a portion. I would be interested in seeing actual references that say it's use is only for removal, not opinions.

lazlo
02-10-2008, 09:08 AM
The tang is for removal. It's not hardened

I just put a morse taper in my Rockwell hardness tester, and the tang is hardened: 45 Rockwell C.

I drove the penetrator into the flat on the tang immediately below the "MT3" label.

Evan
02-10-2008, 09:23 AM
It is extremely difficult to measure a taper, accurately locate the points where the two measurements were made, and then measure the distance between.
It isn't difficult if you have one that fits properly to compare with. Reverse one to the other and tape together. Then measure across them. It should be the same measurement at both ends. Any difference can be attributed to the taper in question.

I just made a MT2 taper last night and did it by using the compound. I had to shift it once since the travel isn't enough to do it in one setup. Finding the correct taper angle isn't hard at all nor is measuring it. Chuck up a good taper and use a dial indicator on the cross slide to touch off the taper at the ends, noting how far you have to wind the cross slide to get a touch. With a dial to measure the carriage travel between touches you are in a position to calculate the taper to parts per thousand, even with cheap equipment.

BTW, the taper I made fits my SB tailstock with about 50% contact from one end to the other. That is pretty good for one that wasn't ground. It holds just fine too.

As for the question of removal vs drive, I think it is pretty obvious. If the tang was intended as a drive it would be hardened. Also, if it is supposed to drive then why all the equipment without that facility, my lathe for instance? The tang is there to protect the spindle as well as for removal. The morse taper and other similar locking tapers are more than capable of providing the necessary drive when in good condition using parts that fit. It may seem necessary that the tang provide drive when using worn or poorly fitted parts but with decent quality machines and well made tooling it's clear that is not the case.



I just put a morse taper in my Rockwell hardness tester, and the tang is hardened: 45 Rockwell C.

I suppose mistakes do happen in manufacturing.

Milacron of PM
02-10-2008, 09:32 AM
Countless times you yourself have asked questions on your own PM forum and
received good answers for the amount of info you provided but you bashed or belittled the poster because they don't have the ability to read your mind. Keep comments in the context of this thread here on this forum. Don't get so desperate for a "come back" that you are conjuring up BS about what happens on another forum.

Evan
02-10-2008, 09:41 AM
Here is what happens when a tool becomes worn and the tang is driving the bit.

http://vts.bc.ca/pics3/mttang1.jpg

It's also not hardened. A single stroke of a file left the mark.

http://vts.bc.ca/pics3/mttang2.jpg

The tool is Comet brand, made in England.

lazlo
02-10-2008, 09:48 AM
I just put a morse taper in my Rockwell hardness tester, and the tang is hardened: 45 Rockwell C.

I drove the penetrator into the flat on the tang immediately below the "MT3" label.

I suppose mistakes do happen in manufacturing.

Sigh. You're going to make me go out and get another one. :rolleyes:

Evan
02-10-2008, 10:24 AM
Yeah. Try a different brand. I was thinking the same thing but I don't have a hardness tester at home.

J.Ramsey
02-10-2008, 10:52 AM
Keep comments in the context of this thread here on this forum. Don't get so desperate for a "come back" that you are conjuring up BS about what happens on another forum.

You would do well to practice what you preach.............look in a mirror.

Milacron of PM
02-10-2008, 11:20 AM
You would do well to practice what you preach.............look in a mirror.Meaningless comment with a definite example to point to.

pcarpenter
02-10-2008, 11:45 AM
I want to say it was Frank Ford's site that showed a quick way to measure tapers. Just stand the arbor on a surface plate or other fairly flat surface. Take a 1-2-3 block and using the knife-edge portion of a caliper jaw, measure the taperered shank with the caliper laying flat on the 1-2-3 block with the block laying on its 1" dimension (1" up from the surface). Then flip the block to the 2" side and do it again. The difference is the taper per inch and can be converted as needed. For perhaps a better sampling, you could go from the 1" to 3" measurement if the length of the taper allows for it.

Nifty idea....but its not mine:)

Paul

J Tiers
02-10-2008, 11:46 AM
OK, now you are assigning dimensions to the taper. I find it difficult to measure tapers with common HSM equipment, and by your reply on the PM thread, apparently you do too;

"Well, I simplified the measurement, to get a "close rough estimate", and found that if a taper is way out of spec, it won't fit well..... Kind of obvious, I guess....... "

We have gone from an assumption to a "close rough estimate". However close and fourth place readings are kind of oxymoronic. It is extremely difficult to measure a taper, accurately locate the points where the two measurements were made, and then measure the distance between. What is the taper of the Bison center using this same "close rough estimate" method?

I do find it more meaningful when actual information is presented rather than a rant because something does not meet with someone's approval.



JC, this has degenerated to basically a PERSONAL ATTACK on your part. Is there a reason for that?

I did not "ASSIGN" dimensions. I measured them.

And it does not matter a whit if it "meets with my approval" (imagine that said in a mincy-wincy falsetto). It is EITHER RIGHT or WRONG. it FITS or it DOES NOT fit. Your approval, or my approval, is irrelevant.

As far as a rant, my original comments were frankly "venting" about the silliness of having a beautiful, but wrong, part.

(You seem to be on a rant concerning me at the moment, if we wish to discuss rants....... We'll have this thread closed and deleted soon.)

NOT ONCE have I demanded Collis perfection for $1, but it WOULD be nice if the part were not COUNTERFEIT. If the part does not conform to the established definition of what it is stated and claimed to be, it is a COUNTERFEIT.

I bought the only offering of that vendor, (Victor Machinery, if you must know), and, ironically, would have happily paid several times more per part to get good parts. (you would have already known that if you had read what I said above)

So much for your assumption of me being a cheap B%$#@!d who wants it all for nothing.

Thanks for the compliment, though.

BTW, I only measured them to satisfy your curiosity, which you expressed so forcefully that you managed to get me interested in it as well. I already knew they had problems which made them unusable for me. "How much", is only a detail.

Anyhow, the taper has machined "edges" where the diameter reduces before the unfinished head starts or the tang begins. I measured the DIAMETERS AT THE EDGES, where there is a definite place for reference. And then the distance "along" the taper between those points. Some trigonometric exercises convert that to an axial distance, and deriving the taper is easy.

The edge gives a decent reference for getting the mic straight across, as well, rather than just guessing at 90 deg.

If anything, the taper would be UNDER-estimated by this method, since the "fat" end edge might have some rounding which would reduce its diameter and make it appear shallower. The error is all to the "steeper" side.

4 digits?

I read it off the mic and had no reason to ditch one or two digits. You'll note the length isn't to tenths......

In any case, the taper was measured as described, and found to be well out, out enough that fairly gross measurement errors would be needed to find it to be "good".

As far as measurement methods, Evan's method of measuring over two is good in some ways, bad in others.

1) it is pretty difficult to hold the two tapers straight and in contact at their max diameter. Any error in that goes right into the readings.

2) You need a "standard" to use as one of the units. Obviously if the parts you check are identical, whether with identical errors or both perfect, they will measure the same everywhere by similar triangles, and no information is obtained.
Therefore the accuracy is dependent on the "standard" taper used for comparison, and is questionable.

Anyhow, rather than some turkey with a bad T/S claiming the parts are crap..... we DO have parts which appear to be WELL out of tolerance.

If you can show how the measurement etc was worthless, I'm listening, but it appears to be good on a geometric basis.

rantbot
02-10-2008, 01:01 PM
A little review of tapers and locking angles might be in order. Just to liven things up a little.

In design of machine elements, there is a "locking angle" which is determined by the coefficient of friction.

http://mysite.verizon.net/vzeehv3p/plane.jpg

Here is a block on an inclined plane. The coefficient of friction for this particular pair of materials (plane and block) is F. To measure F, increase the angle of the plane until the block starts to slide. That angle is A. Then the coefficient of friction F is the ratio of the "normal" force N (that is, the force at right angles) pushing the block into the plane, to the "tangent" force T trying to slide the block along the plane. The load force L is the weight of the block (it should be pointing straight down - I didn't sketch it quite right). At angle A, the normal force pushing the block against the plane is N=LcosA, and the tangent force pushing the block downward along the plane is T=LsinA. The ratio of the two forces is the coefficient of friction - F=T/N=LsinA/LcosA=sinA/cosA=tanA. Very simple; that all follows directly from the definition of Coulomb or "dry" friction. Real life is complicated a bit by the fact that static or "starting" friction is usually a bit higher than dynamic or "sliding" friction, but both can be measured the same way - by measuring the angle A.

The angle A is also, not too surprisingly, the "locking angle." At angles less than the locking angle, a load L applied vertically can't push the block down the plane, no matter how large the load is. The friction force will always be enough to prevent movement. Angles greater than the locking angle don't lock. Any force L at all will cause the block to slide down the plane.

The concept of locking angle is vital in design of, say, gear trains. A tooth contact angle less than the locking angle will be a locking gear. A good example is a typical worm gear. Because of "locking" it won't transmit a torque backwards - a torque applied to the worm will move the gear easily, but a force applied to the gear will not turn the worm. The parts will break before the worm will be rotated by the gear. Exactly the same effect prevents bolts from spontaneously unscrewing themselves as soon as a load is applied. Similarly, most leadscrews are non-reversing - the load doesn't rotate the screw, no matter how great it is. By increasing the contact angle (done by increasing the helix angle of the thread or worm), this locking effect can be eliminated. A multi-thread or multi-lead leadscrew, or worm-gear worm, can be a reversing (that is, non-locking) mechanism. The idea, of course, is to use the geometry of the parts and interface - that is, the contact angle - to get the system to work the way desired. In some applications locking is good, in others it's not. The machine designer has to keep track of this.

This is all very simple geometry, but not as well understood as it should be. I've run into engineers who have never realized it.

Tapers can also be locking or non-locking. Non-locking tapers are fine for one of the uses of tapers - alignment of parts - but in practice the locking feature is usually beneficial, so most of the tapers we see are locking ones. R-8 has a non-locking taper, which is one reason why you'll never see it in a lathe tailstock. A locking taper won't permit movement under a torque load so long as it has an axial load sufficient to keep it locked. The situation is a bit different from the inclined plane described above, because on the inclined plane, the force trying to cause slippage, T, is always proportional to the applied load, L. This is not automatically the case with a taper. When drilling with, say, a tail stock, the axial force (the source of the locking force) is not always proportional to the torque on the drill. When drilling, yes, there is a positive axial force, and if the taper is steep enough (No. 2 Morse, say, vs. R-8) the taper will lock, and the drill bit will be held steady against the torque forces needed to do the drilling. But as soon as we start to back the drill out, we will have (relatively small) negative force - that is, tension instead of compression - on the taper, and it can no longer lock against the small torque caused by the drag of the bit on the sides of the newly-drilled hole. Then the drill bit (or chuck) will spin. The way to prevent this is to apply an external axial load sufficient to keep the taper locked - which is what a drawbar in a mill spindle does - or to bang the taper into place. Because of the elasticity of the steel (Young's modulus), banging the taper into place gives us an elastic force analogous to the normal force N or the load force L in the inclined-plane situation, and that in turn gives a tangent force T (depending on the taper angle, the coefficient of friction of the metals, and how hard the bang was) sufficient to take the place of the external load we don't have.

Interestingly enough, it is not strictly necessary that the taper fit well in order to lock. Note that in the inclined plane problem, the contact area doesn't appear in the formulas. A larger area does not give us more "friction force." For any given material, the more gradual the taper, the higher the radial force generated at the contact patch - whatever its size - when the taper is banged in. However, when the fit is poor, the alignment of the parts will also be poor, which means that the taper isn't doing its primary job.

Here is a Sharpie mark on a 2 Morse center. This center has been placed in a 2 Morse taper socket (not banged in!) and rotated slightly, thus scraping off some of the Sharpie ink. It's clear that contact is pretty decent over the length of the socket (which is shorter than the center, so the ends of the center didn't make contact at all, and the Sharpie line there is undisturbed).

http://mysite.verizon.net/vzeehv3p/taper4.jpg

Here is the same center placed in a 7 Brown & Sharpe socket. The tapers are very similar, but that's not close enough. Only a narrow ring has any contact at all. If banged in, this combination could be expected to resist torque as well as the proper 2 Morse center and socket, but the alignment of the center in the B&S socket will not be good.

http://mysite.verizon.net/vzeehv3p/taper5.jpg

rantbot
02-10-2008, 01:04 PM
So much for your assumption of me being a cheap B%$#@!d who wants it all for nothing.
Nothing wrong with cheap. None of us have infinite resources. Besides, as a new England skinflint of frugal Scots antecedents, I pride myself on my traditional "respect" for money.

J Tiers
02-10-2008, 01:23 PM
Thank you.

I DO often find that more cost is sometimes cheaper overall..... :) Although I AM disinclined to spend extra.... (Swedes)

Great explanation of tapers.

One thing......

The "holding" of an improper taper against pulling out is somewhat dependent on the "stiction" factor. It's harder to start it slipping than to keep it going once started.

BUT, if the thing WOBBLES, due to the improper taper allowing movement, then the "stiction" is broken, and you have ordinary sliding friction.

That's why what is implied by the area not appearing isn't as true in reality as it is in theory.

But I totally agree with your statements. They agree with my intro to M.E. distribution courses.... Thanks for the reminder!

Evan
02-10-2008, 02:59 PM
Interestingly enough, it is not strictly necessary that the taper fit well in order to lock. Note that in the inclined plane problem, the contact area doesn't appear in the formulas. A larger area does not give us more "friction force."

Yes, it does. The reason stiction exists is the operation of the Van der Waals forces. These are area dependent in a direct ratio assuming the surfaces are in sufficiently close contact. The better the fit of the taper the higher the stiction force that must be overcome to make it move again. This is also why PTFE doesn't exhibit stiction. It has no exposed dipoles and doesn't display externally visible Van der Walls forces from the molecule. Stiction isn't friction but the distinction is irrelevant when holding power of the taper is the issue.

JCHannum
02-10-2008, 03:37 PM
Duplicate post somehow.

Evan
02-10-2008, 03:54 PM
Holding two Morse tapers together as Evan describes is of little use, as it merely tells whether they are the same or different. Again without a known standard, it is not much use.
Ahem, I gave a known standard, a taper that fits correctly. That is all you need to compare to. That is also all I needed to make a #2 MT last night that fits correctly.

JCHannum
02-10-2008, 04:07 PM
Mercy, I have tried not to become personal, and certainly have made no reference to your financial practices or parentage.

You have never displayed a reluctance to present your views on a subject, and are frequently critical of others. I find it surprising you take offense when someone offers opposing views of your posts.

You have stated the taper was out of spec. I questioned how you determined this, since you had no true reference. When two or three items are compared, one can only determine they are the same or they are different unless one is a known standard. In this case, none of the tapers was.

You have since made an attempt to measure them, in your own words; "a close rough estimate". Measuring a taper with a micrometer with flat faces is very difficult. It is not a problem on the large end if there is a sharp break, but the small end is problematical. It is also very difficult to locate the exact point where the measurement is made, and difficult to measure the linear distance between the two points. This is what I referred to. Truly accurate measurements will require some rather complex setups, probably a sine bar, Jo blocks and a height gage on a surface plate is the best setup for the home shop, and I agree with you that the exercise is not worth the effort.

Holding two Morse tapers together as Evan describes is of little use, as it merely tells whether they are the same or different. Again without a known standard, it is not much use. As you pointed out that method has it's own inaccuracies.

I am not picking on you (maybe I am a little), but just trying to point out that some things are not always as simple as they seem. I don't know if the Indian taper is out or not. It probably is, and the Bison probably is very close to ideal. For most applications, the Indian taper is probably acceptable, for yours, it is not.

You do present a very good point in that it is prudent to inspect your purchases to make sure they are capable of giving you the results you are looking for.

As far as Morse Tapers and the purpose of the tang, I have presently four sources that identify the tang is to drive or share the driving of the drill. These are three text books and one manufacturer's handbook as follows:
"Machine Tool Operation" Henry Burghardt 1919, Part 1, page 142
"Bendix Cutting Tool Handbook" copyright 1972, page 169
"Machine Tool Operation" 1959 Burghardt, Axelrod and Anderson, pp 175 & 176 (While this is the same title and shares Burghardt as author, it is a complete rewrite.)
"Metalwork Technology and Practice" 1975 Ludwig, McCarthy and Repp, page 483

If anyone cares to refute the purpose of the tang, I request that he provide as least as many documented references stating that it's only purpose is to expel the drill.

The Morse Taper was developed over one hundred years ago as a means to drive a drill. For whatever reasons, it has become a standard in many applications. When it was first designed, the horsepower of today's machines and the materials encountered in tools and workpieces were never envisioned.

The Morse Taper was designed for low spindle power and easily machined materials. Originally, it was provided in six sizes, 1 through 6. Number 0, stub and 1/2 sizes were added at later dates. Each original size was designed to handle a specific size range of drill, and as the drill became larger, holding power became reduced. For this reason, it is not good practice to use increasing adaptors when driving drills. A lathe with a MT#2 tailstock will comfortably handle most smaller drills with MT#2 shanks, but using an MT #3 X #2 or #4 X #2 increaser without mechanically restraining it externally is asking for problems.

Today's drills are frequently selectively hardened, the shank being drawn back to a lesser hardness than the cutting flutes. This is done to maintain a sufficient hardness on the cutting edge while not making the shank brittle. The process and degree of hardness will differ according to size and manufacturer. There is not one statement that will fit all cases.

I find it interesting that Millipore will lock threads on PM that offer meaningful discussion on imported tooling, but come over here and interject his own meaningless comments on the same thing.

JCHannum
02-10-2008, 04:14 PM
Ahem, I gave a known standard, a taper that fits correctly. That is all you need to compare to. That is also all I needed to make a #2 MT last night that fits correctly.
Somehow, my comments were posted before I finished. You merely made a taper that fit your tailstock. That is a simple operation. My comments are directed toward determining if a given taper is in spec. While it might fit your TS, that is not a standard.

Evan
02-10-2008, 04:23 PM
If anyone cares to refute the purpose of the tang, I request that he provide as least as many documented references stating that it's only purpose is to expel the drill.
I didn't say that, did I? Also, exactly how does the quantity of references make them correct rather than just common belief? That is a frequently used logical fallacy. Just because "everybody" thinks something is so doesn't make it true. I showed you evidence of what can happen if the tang is needed to drive the taper in the event of poor tool holding. Now it's your turn to make me believe that Morse intended that as a normal mode of operation rather than a protection against damaging the spindle. Having to rely on the tang to drive the bit means the machine and/or bits are worn beyond normal operational standards.



While it might fit your TS, that is not a standard.

For my purposes it is the only standard that matters.

JCHannum
02-10-2008, 04:36 PM
You merely showed a twisted tang that was a result of some form of misoperation.

Four acknowledged, documented sources is far from "common belief". If your opinion is that the function is any other reason than I have presented, supply documentation to support that.

J Tiers
02-10-2008, 05:57 PM
You have since made an attempt to measure them, in your own words; "a close rough estimate". Measuring a taper with a micrometer with flat faces is very difficult. It is not a problem on the large end if there is a sharp break, but the small end is problematical. It is also very difficult to locate the exact point where the measurement is made, and difficult to measure the linear distance between the two points. This is what I referred to. Truly accurate measurements will require some rather complex setups, probably a sine bar, Jo blocks and a height gage on a surface plate is the best setup for the home shop, and I agree with you that the exercise is not worth the effort.

Holding two Morse tapers together as Evan describes is of little use, as it merely tells whether they are the same or different. Again without a known standard, it is not much use. As you pointed out that method has it's own inaccuracies.

I am not picking on you (maybe I am a little), but just trying to point out that some things are not always as simple as they seem. I don't know if the Indian taper is out or not. It probably is, and the Bison probably is very close to ideal. For most applications, the Indian taper is probably acceptable, for yours, it is not.



Good points.

Let's see if they stand up.

The "attempt" was pretty successful, I believe. Here's why.

The error was determined to be about 0.007. What would it take to get that error, in terms of a position error on the taper?

At 0.599 per 12", it takes about 0.120" position error along taper to get to 0.006 error of diameter. That seems pretty large, I think I can (almost anyone can) do better than that.

I will allow an error band of 0.05 on length, since I made a legitimate effort to hit just visibly "ON" the ground area above the tang, which has a machined 'step".

I will agree that I can't, therefore, be sure within 0.002 or so, of the ACTUAL taper.

But I will NOT agree that I cannot be sure *within the measured error* or more, that the taper is WRONG. IOW, I KNOW it's wrong, but not exactly how much, since my measurement is more accurate than it has to be to cover the observed error.

They might be outside the tolerance by 0.002, or might be outside by the 0.004 I suspect, or it might be outside by a full 0.006 (0.002 over my measurement). Actually less, since the 0.05 is the probable "band" and not the +-.

yes the two tapers is probably of less use than making a two point gage with two sharp edges with a known space between, and locating them a known distance apart.

Without a known standard, all the objections you brought up to a fit comparison are in play. There is, again, no info other than "these don't match" which was known to begin with.

lazlo
02-10-2008, 06:03 PM
As far as Morse Tapers and the purpose of the tang, I have presently four sources that identify the tang is to drive or share the driving of the drill. These are three text books and one manufacturer's handbook as follows:

"Machine Tool Operation" Henry Burghardt 1919, Part 1, page 142
"Bendix Cutting Tool Handbook" copyright 1972, page 169
"Machine Tool Operation" 1959 Burghardt, Axelrod and Anderson, pp 175 & 176
"Metalwork Technology and Practice" 1975 Ludwig, McCarthy and Repp, page 483


My machinery library is almost complete -- I have three of those four books :)

From the 1959 Burghardt

"The purpose of the tang is to help drive the drill, since the hold of the taper alone is not sufficient."

...and for Evan:

"It must be understood, however, that the tang alone is not sufficient to drive the drill or other cutting tool, and consequently, the taper shank and hole must be properly fitted, clean and dry, and the shank must be firmly driven home or the taper will not do its share, and the result will be a twisted-off tang."

Evan
02-10-2008, 07:04 PM
That does not explain how I am able to drill large holes in steel with MT3 drill bits held in the headstock taper of my lathe. No tang driving and no drawbar. Still works though. The tang isn't needed if the equipment is in good shape. That convinces me that the purpose isn't to drive the bit. Those quotes are not convincing as experience proves them wrong. I am not offering an opinion, just my experience using this sort of equipment over the decades.

J Tiers
02-10-2008, 08:19 PM
If ANY of youse guys had ever had to dig a center out of a spindle, you'd no longer attempt to convince us that the taper can't hold the drill etc.

I've had to step drill out, and then chip out, a center from a morse taper. No amount of axial knocking and banging that we were willing to do to the spindle worked, that thing was in to stay. We even took out the spindle and tried freezing, heating (as much as we dared) etc. No dice.

It is particularly important that it was a CENTER, since it COULD NOT have been spun in the taper, as a drill etc might have been. (and it had not been, it was known to have been forced in hard.)

After the bulk of the material was removed, tediously, the case hardened shell of the center popped out suddenly. No particular galling or roughness was visible. Therefore it wasn't "spin-welded" in, it was just plain stuck.

Quite clearly it is possible to get a taper tight enough to resist even a heavy axial impact in the "removal direction", let alone a turning force.

As far as authors and their opinions, authors used to deny gravity, state the earth was flat, etc. Writing maketh not truth, truth is self-evident when examined with an open mind.

I have no doubt that the tang CAN drive, to some extent.

But SHOULD it be ALLOWED to drive the drill?

The tang is normally only perhaps 2/3 of the diameter of the taper. It may be substantially smaller than the drill diameter. Not a good start, lots of leverage against it.

With an MT2, you can get a 3/4" drill, but the tang is only 1/2".

Then also, in order for the tang to drive, the taper must have slipped more or less, since the tang slot is considerably larger than the tang thickness. it is unlikely that the shank was inserted with the tang tight against the "driving surfaces"....

If the taper has slipped, it's friction has dropped a LOT, the tang will take a goodly impact, and will have to bear most of the force of driving the drill.

Since drills can be held by the friction of three small jaws on a straight shank, at or below the drill diameter, I would be confident that a taper of a larger diameter than the drill would easily be able to hold the drill, if knocked-in solidly.

Now, there ARE key-drive tapers. And there are Collis drill-holders for tanged straight shank drills,

The tanged drills have a tang at the same diameter as the drill, and the tangs are a fairly close fit in the holder. That is at least 30% better than the tang on a taper.

Keyed tapers:

American Standard nose key drive with drawbolt, self-holding tapers......

same taper as morse, but has keys on the spindle face, at a larger diameter than the taper gage line (good leverage). No tang, uses drawbar(ASA B5.10-1963)

American standard taper drive with keeper key, self-holding tapers.

Same as morse, with a key driven in through the socket and shank crosswise. Still has the tang, no drawbar, the key holds in the shank (and won't let it turn, BTW). (also ASA B5.10-1963)

I have left out the 40 taper etc, as they are intended to NOT be a "holding" taper.

Then Evan brings up a good point, that many T/S rams have no tang slots, yet they drive the drill quite well at large diameters.

Drills with twisted-off tangs will still be usable if the tapers are OK, and I have drills with no tang which work well, drive just fine.


My conclusion based on experience, as well as on the geometry of the drill and tang is that:

The tang is indeed "geometrically able" to drive the drill, in that it has a physical interference which will in fact put a turning force on the drill shank.

However, one would be far wiser NOT to let it do so, but rather to make the taper do the work, since the tang is usually soft and relatively weak.

The friction of the taper and socket is fully capable of doing all the driving if correctly installed in an undamaged socket.

lazlo
02-10-2008, 08:34 PM
That does not explain how I am able to drill large holes in steel with MT3 drill bits held in the headstock taper of my lathe.

You have a light-weight hobby lathe. The machine texts JC posted are referring to industrial machines.

lazlo
02-10-2008, 08:36 PM
Then Evan brings up a good point, that many T/S rams have no tang slots, yet they drive the drill quite well at large diameters.

Many tailstock rams have no tang slots?

I thought most lathes with MT3 and up tailstocks have drive slots? I know the Clausing 5900's and 6900's do, and most (all) of the Monarchs.

The 10EE, for example, which uses an MT2 tailstock, has two hardened setscrews in the tailstock spindle that engage the tang, preventing rotation of the chuck or MT2 drills. The fact that Monarch put those tang capture screws there is another clear indication that the tang is intended for driving...

JCHannum
02-10-2008, 08:41 PM
You folks are welcome to operate your machines in any way you see fit. If asked for advice, I will pass on that of acknowledged machine trades instructors and tooling manufacturers. If the Morse Taper were such a powerhouse one must question why it sees such little application in the real world.

J Tiers
02-10-2008, 08:48 PM
You folks are welcome to operate your machines in any way you see fit. If asked for advice, I will pass on that of acknowledged machine trades instructors and tooling manufacturers. If the Morse Taper were such a powerhouse one must question why it sees such little application in the real world.

Probably because it is a pain to install and remove..... :D

When "in" well enough to drive effectively, it is hard to get back out.

The 30, 40, or 50 taper have tang drive and easy removal.

Morse and the B&S tapers DO get a lot of use, though...

And, BTW, the drawbar in a drawbar-held taper does not do *one thing* to prevent rotation. And if there is a drawbar, there is NO TANG.

Yet drawbar-held tapers drive large milling cutters...... and do not slip much, I have never had it happen although I have had arbor keys sheared through.

"Well", you say, "they are held in solidly". And that is true.....

But of course the only resistance to ROTATION is due to friction...... the drawbar merely ENSURES the existence of that friction.

Evan
02-10-2008, 09:42 PM
If the Morse Taper were such a powerhouse one must question why it sees such little application in the real world.

It has been superceded by better designs, in many cases, but not all. The industrial suppliers still stock Morse taper tooling so they must be selling it. Also, for an obsolete type why is it that everyone associated with the field knows at least the name Morse taper while others are unknown to many.

Incidentally, the KBC catalog has about 70 Morse taper line items with a total inventory of around 23,000 pieces. That's one heck of a pile of NOS for a product that isn't used much anymore.

JCHannum
02-10-2008, 10:02 PM
I did not say that it was not in use. It is still used. However, it's most common application is on drills, which is what it was designed for and what probably acounts for the lion's share of those 70 line items. It is still also common in tailstock toolholding systems and some other light duty applications, but beyond those, it has largely been supplanted by other toolholding systems.

Interestingly, Atlas, well known ancient manufacturer of cheap, underpowered, pot metal geared home shop machines somehow felt compelled to equip the #2 MT arbor on their milling machine with a flanged driver which incorporates two drive pins to prevent slippage.

J Tiers
02-10-2008, 10:39 PM
Interestingly, Atlas, well known ancient manufacturer of cheap, underpowered, pot metal geared home shop machines somehow felt compelled to equip the #2 MT arbor on their milling machine with a flanged driver which incorporates two drive pins to prevent slippage.

The MT2 is pretty undersized for a 3" or 4" cutter, I'd tend to agree with their decision.

While I claim that the friction is good enough for a drill of the taper size, I don't claim that there is NOTHING which might slip a taper.

That jammed taper would have driven anything up to "twist-off" torque, but it is hardly a practical situation.

There is quite a lot of difference between a tang drive and the drive via a flange. For the same force on the "key", a LOT more torque is transmitted by the flange due to the far larger diameter.

Does not remotely compare to a tiny tang of 1/6 the cutter diameter.

But, I have been under the impression that the Atlas drive flange was not quite what it seemed, that it clamped in some way to the arbor or spindle, and wasn't an integral part.

Also that it was not offered on all of the mills, but may have been an option. Pictures on the UK site don't show it in all pics, and in fact I didn't see it on any, although I know it existed.

Is that not correct?

rantbot
02-10-2008, 10:47 PM
This statement -


From the 1959 Burghardt

"The purpose of the tang is to help drive the drill, since the hold of the taper alone is not sufficient."
is basically correct, but somewhat misleading.

The taper, unless grossly undersized for the drill, can transmit enough torque to drive any reasonable drill bit.

But in part of the drilling operation it tends to not hold well, because the axial load - necessary to provide enough friction force at the taper interface - is zero or negative during those operations ... as I mentioned above. At those times it would be nice to have another mechanism to drive the drill bit. It need not be a high-torque mechanism, but it should be one which doesn't rely on friction at the taper surface to do its job. A small tang would be adequate. The alternative is to bang the taper in hard, which means banging on the business end of the drill bit, which is damn near certain to lower the bit's efficiency as a cutting tool.

So the taper and the tang do their jobs at different times, and in different torque regimes.

My lathes don't happen to have tangs. They drill just fine, but the tapers do tend to pull out and disengage when I back the bits out of the holes. Tangs would be nice to prevent the drills or tailstock chucks from spinning. A drawbar arrangement would be even better, even though a drawbar wouldn't itself ever exert any driving torque; it would just keep the taper engaged. It wouldn't be needed when drilling, as the drill bit would then exert the force needed for the taper to exert whatever drive torque was needed.

Renegade
02-10-2008, 10:51 PM
I don't post much... mostly sit back and read... you guys know most of it anyway.
I will add to lazlo's book listings by adding Machine Shop Practice volume 1 first printing 1979 by Karl H. Moltrect Ch.4 page 83 definitions of the various elements of a twist drill.

Tang-the flattened end of a tapered shank, intended to fit into a driving slot in a socket or machine spindle.

J Tiers
Quit beating a dead horse, it only makes it tougher to swallow.

Evan
Ditto the above, your intelligence at times is bewildering, put it to a better use.

Milacron
Your vile retorts suggest being spoiled as a child, If your married with children I pity them.

lazlo
02-10-2008, 11:58 PM
I will add to lazlo's book listings by adding Machine Shop Practice volume 1 first printing 1979 by Karl H. Moltrect Ch.4 page 83 definitions of the various elements of a twist drill.

Yep, I've got both volumes of Moltrecht. They're my favorite of all of them.

I figured Moltrecht would have it described into there somewhere :)

oldtiffie
02-11-2008, 02:59 AM
I read all of the opinions and issues (non-issues as well!!).

If my mechanics/physics is correct, there has to be a reaction to all of the torque/s generated here.

That should be no problem on a drill or a mill where most of the reactive force is on a spline and the drill tang, if it has one, is engaged by the slot for it in the spindle.

On the tail-stock of a lathe, the re-active forces are on either a single key (better/bigger lathes) or a small single cylindrical projection from a screw etc.

In all of this discussion to date there is no mention of the tail-stock quill retention devices let alone failure of any of them. So, either they are very good or the forces/torques are not as high as they might otherwise seem to be.

My lathe is a small 3-in-1 with an MT2 TS taper. I never put in a drill that cuts or enlarges a hole in a job in the head-stock by more than 1/4" - usually less. I usually start off with a 1/4" drill followed in succession by 3/8", 1/2" etc.

I am in no hurry at all - let alone in a rush to drill big holes in one go or to make chips at a commercial rate.

If I am in a rush or hurry, its time to either not go into the shop in the first place or to leave until the "rush" is over.

I use my shop to relax in - not to rush, "cut corners" or get stressed as those are recipes for an accident.

I am in a small HSM shop.

If I were in a commercial shop with "big" machines it might be different.

I am not sure that the taper under discussion is such a big source or reason for as much concern and heated debate as there is.

JCHannum
02-11-2008, 07:55 AM
.......it was not offered on all of the mills, but may have been an option. Pictures on the UK site don't show it in all pics, and in fact I didn't see it on any, although I know it existed.

Is that not correct?

No, that is not at all correct. The spindle, change gears and Timken bearings from the 6" lathe were incorporated in the Atlas milling machine. The spindle nose was threaded and the driver threaded in place. A driver was furnished with each cutter arbor sold. The arbor also required a drawbar.

The Atlas manual states "The arbor driver is screwed on the spindle nose and the two prongs drive the cutter arbor". I know, I know, documented statements by manufacturers have no validity, but I thought I would point that out.

A shell end mill driver that threaded directly on the spindle was also available, as were straight arbors for angular cutters which used the driver. A draw in end mill holder with 1/2" capacity was available which did not have the drive flange, bushings were available for smaller tooling. This would set the max at 1/2" end mill for the MT#2.

The largest cutter they sold was 2-1/4" X 1. Diameter was limited by the overarm support, I don't know what that dimension is, but I would hazard a guess that 3" or 4" cutters were not in the design parameters. The recommended motor horsepower was 1/3 @ 1725RPM. It would appear they anticipated slippage even in this low power application.

Renegade, thanks for the Moltrecht reference. Moltrecht and Burghardt are among the best references and authorities available. I don't have any Moltrecht books at this time or he certainly would have been included.

J Tiers
02-11-2008, 08:10 AM
odd that none of the pictures show it.

But I was correct, it threads on. I knew it wasn't an integral part.

In any case, with a large cutter 3 x the taper diameter, it was a smart move.

The tang, driver or not, is only 1/5 the cutter diameter, and would have no chance.

On my MT3 spindle, I have jammed 4" cutters, and had them slice a 1/4" key, with 1/4 HP input power.... So much for low power.......

But the taper never slipped.

I still say that IF the tang is intended to drive the drill, it is a stupid arrangement and would be better not depended on.

The mill setup is intelligent, and makes sense. TWO keys, at 5X the diameter, suggests the ability to take at least 10 x the torque.

Milacron of PM
02-11-2008, 08:29 AM
I don't post much... mostly sit back and read... you guys know most of it anyway.
Milacron
Your vile retorts suggest being spoiled as a child, If your married with children I pity them. So my statements such as
"Meaningless comment with a definite example to point to" is a "vile retort" but somehow your personal insult both to me and my family is not ? Such hypocrisy is astounding.

torker
02-11-2008, 08:42 AM
So my statements such as
"Meaningless comment with a definite example to point to" is a "vile retort" but somehow your personal insult both to me and my family is not ? Such hypocrisy is astounding.
Don... piss off. Err.. Milacron (stupid name if you ask me). You are "supposed" to be the head of the large professional family but you just can't help coming over here stirring up **** with the little guys.
It makes me laugh when the newer guys around here defend you. They don't know you've been trying your best to stir the pot here for years.
You've shown your true colors yet again.
I've said it before.. you are a knowledgable fellow...too bad you choose to act like a jerk.
Russ

JCHannum
02-11-2008, 09:08 AM
odd that none of the pictures show it.

But I was correct, it threads on. I knew it wasn't an integral part.

I still say that IF the tang is intended to drive the drill, it is a stupid arrangement and would be better not depended on.

The pictures on Tony's site do show it in place. They also show one with a dovetail cutter held in the endmill holder with the driver in place as a thread protector.

It is an integral part of the arbor installation and the instructions so describe. As with any machine, other options are available, and I mentioned all that are offered in the 1945 catalog.

Nobody said the tang is intended to drive the drill. It is intended to share the force with the taper, each adding it's own component. It was you and Evan who seemed to feel that the sole purpose of the tang was for removal. I merely presented documentation to the contrary.

Milacron of PM
02-11-2008, 09:51 AM
Don... piss off. Err.. Milacron (stupid name if you ask me). You are "supposed" to be the head of the large professional family but you just can't help coming over here stirring up **** with the little guys.
It makes me laugh when the newer guys around here defend you. They don't know you've been trying your best to stir the pot here for years.
You've shown your true colors yet again.
I've said it before.. you are a knowledgable fellow...too bad you choose to act like a jerk.
Russ Calm down and re read all I've written in this thread. Note that my first post in this thread was my opinion based on experience with tooing from India. Was that coming over here to stir up things ? No, it wasn't...obviously.

Now, think about my calling out Ramsey for illogical statements and suppositions as they pertained to JT's posts...just defending JT's position basically. Never any personal insults, just pointing out illogic. Even with Renegade's "vile" insults I refrain from attacking him personally. And now you..."stirring the pot", "stupid name", "jerk" more personal attacks....such a hypocrite.

Bottom line is I NEVER come over here "to stir the pot"....maybe I did years ago a few times but not now. I come over here when something that I know about catches my eye and I can't resist responding to it. I know a bit about Indian tooling, and that's why I began to post in this thread. The rest of it came about when Ramsey made his presumptions that irritated JT, and I simply defended/confirmed why JT should have been annoyed and it escalated from there.

Evan
02-11-2008, 10:29 AM
It was you and Evan who seemed to feel that the sole purpose of the tang was for removal.

THAT IS NOT WHAT I SAID. To refresh your obviously failing memory here is what I said in post #44, the first time I mentioned it.

The tang is for removal. It's not hardened and will twist if allowed to take torque loads because of a poor fit of the taper in the socket. The reason it is made as a flat tang is to prevent spinning of the taper in case of looseness so that the spindle isn't damaged by such spinning, not to provide drive. It's a safety feature as well as a removal feature. It's better to damage the drill bit than the spindle.

Not only is removal not the SOLE purpose (which I have never said) but the purpose I explain makes a lot more sense in light of the fact that many machines don't make use of the tang and apparently don't need it.

JCHannum
02-11-2008, 10:39 AM
THAT IS NOT WHAT I SAID. To refresh your obviously failing memory here is what I said in post #44, the first time I mentioned it.

The tang is for removal. It's not hardened and will twist if allowed to take torque loads because of a poor fit of the taper in the socket. The reason it is made as a flat tang is to prevent spinning of the taper in case of looseness so that the spindle isn't damaged by such spinning, not to provide drive. It's a safety feature as well as a removal feature. It's better to damage the drill bit than the spindle.

Not only is removal not the SOLE purpose (which I have never said) but the purpose I explain makes a lot more sense in light of the fact that many machines don't make use of the tang and apparently don't need it.

Sorry Evan, my memory is not failing at all, and it is a shame that you have to resort to veiled insults to validate your argument. Your post states "The tang is for removal." That is a pretty clear statement.

You continue that it is not hardened, which is not true in all cases, and follow with some nonsense about what happens if the tool becomes loose.

If you can present some factual data to verify that, we can add that to the use of the tang. Otherwise give it up.

torker
02-11-2008, 10:58 AM
Don.. Ya I'm sure you do know a lot about Indian tooling etc. I respect what you have to say about most machinery/tooling related things. It's the other crap that gets tiring.

Evan
02-11-2008, 12:23 PM
Sorry Evan, my memory is not failing at all, and it is a shame that you have to resort to veiled insults to validate your argument. Your post states "The tang is for removal." That is a pretty clear statement.

The statement "The tang is for removal" is not exclusionary and is further amplified by my comments immediately following. My comment about your memory was intended because this is the second time I have pointed this out. I did not say "The tang is only for removal". I said only two sentences later "It's a safety feature as well as a removal feature." I can only judge your memory capability by what you post here. While you may not have problems I know I do.

JCHannum
02-11-2008, 01:16 PM
Sounds like Clintonian lawyerism. "It depends on what the definition if is is."

My memory is good enough to remember that you made the statement, "The tang is for removal.", which leaves little room for doubt.

Are you saying you didn't mean what you said, you meant what you didn't say? It is kind of confusing at this point. It makes little difference, since you still have not furnished any proof, whatever you did or did not say has no validity.

dan s
02-11-2008, 03:56 PM
for some reason i think we are two post away from... :D

http://www.funnypictures.net.au/images/machine-gun-cat-animation.gif

Renegade
02-11-2008, 04:07 PM
So my statements such as
"Meaningless comment with a definite example to point to" is a "vile retort" but somehow your personal insult both to me and my family is not ? Such hypocrisy is astounding.

I never insulted your family. Look up the word "pity" in the dictionary.
What would be astounding would be the fact that you don't treat or talk to them way you do people on the internet.

Evan
02-11-2008, 06:46 PM
Are you saying you didn't mean what you said, you meant what you didn't say?
I meant exactly what I said. Are you having eye trouble also?


It makes little difference, since you still have not furnished any proof, whatever you did or did not say has no validity.

Proof? My lathe has no tang "drive". Have you ever seen a South Bend Lathe?

oldtiffie
02-11-2008, 08:46 PM
for some reason i think we are two post away from... :D
http://www.funnypictures.net.au/images/machine-gun-cat-animation.gif

Yep - I'd agree with you Dan.

Its about time the "slamming" stopped and we got back to topic or the thread might well be locked or deleted.

It might lead to this as well - .

or:
http://i200.photobucket.com/albums/aa294/oldtiffie/Funnies/Grilla1-1.jpg

or:
http://i200.photobucket.com/albums/aa294/oldtiffie/Funnies/Rambo1.jpg

or if you really rub each other the wrong way too much or too often:
http://i200.photobucket.com/albums/aa294/oldtiffie/Funnies/picmactchstick.gif

rantbot
02-11-2008, 09:23 PM
Its about time the "slamming" stopped and we got back to topic or the thread might well be locked or deleted.
Oh no, things are just warming up.

I've already given the lecture on locking angles. Now for a much shorter one on friction and models.

"Coulomb friction" is an engineering model, in the same sense that the Bernoulli streamline, the Timoshenko beam, the ideal gas law, the Hamiltonian integral, Seidel aberrations, Stephan-Boltzmann emissivity, Gaussian optics, or Newtonian viscosity are engineering models. They don't account for all possible phenomena, and don't need to - they are widely used because in a great many cases they are "good enough." Recall what I have written earlier about "good enough" being "perfect" in engineering-land. Experience and professional judgement determine "good enough," which is one reason why just having access to a CAD system, or a handbook full of formulas, doesn't turn the man on the street into an engineer, any more than a first-aid manual turns him into a surgeon, or the Elements of Style turns him into a writer.

The Coulomb model of friction has two components, a static and a dynamic coefficient. Static is "sticking" friction, dynamic is "sliding" friction. These are the numbers one finds when one looks up "coefficient of friction," or which one measures with simple apparatus (an inclined plane and a protractor). These coefficients are independent of contact area, and independent of sliding speed (except for the trivial case - that is, the speed involved with the static coefficient is zero, as per the definition of "static"). This is very hard to pound into the heads of undergraduates; perhaps the best way is to demonstrate it in the lab. Fortunately the lab apparatus is simple, as mentioned above.

One of the clues that the Coulomb coefficients are independent of velocity and load is that the "coefficient of friction" is not expressed as "per square foot" or "per feet per second." The coefficients are not functions of these variables. And neither are Coulomb friction forces. The relationship is very simple (always a good feature of a model) -

http://mysite.verizon.net/vzeehv3p/friction.jpg

The force needed to drag the block of weight W is F=fW, where f is the dynamic coefficient of friction (if the block is already moving) or the static coefficient of friction (if the block is stationary). Of course that expression for F isn't the whole story, expecially in the static case, as the acceleration of the block requires force as well - (F=Ma). But the expression for the force needed to overcome friction is very simple in the Coulomb model. This is not to say that interesting things aren't possible. Here's an old test favorite from dynamics courses -

http://mysite.verizon.net/vzeehv3p/rollers.jpg

The rollers are on fixed axles, separated by a fixed distance, and rotate as shown - the speed doesn't matter so long as it isn't too slow. The coefficient of friction between the rollers and the board sitting loosely on top of them is f, and the board is of mass M. The board will oscillate along the x (horizontal) axis. Derive the equations of motion in terms of f, M, and the distance between the rollers, and solve for the frequency of oscillation.

I'm not going to do the math here; the idea was just to demonstrate "fun with friction."

JCHannum
02-11-2008, 09:35 PM
I find your references to my memory and vision insulting. If that is the only ammunition you have left please refrain from replying.

You chose to interject your opinion into a discussion as the use of the tang on a Morse Taper. The discussion was whether the tang was intended to provide a driving function in addition to that of the taper, or only for removal. You stated; "The tang is for removal. It is not hardened and will twist if allowed to take torque loads....." That certainly is an exclusionary statement in the context of the discussion.

You continued to state the tang is not hardened, which is not true in many cases, and is the decision of the manufacturer for the performance of the drill.

You felt further called upon to add some other nonsense which has no bearing on the discussion. I did not question this, but I now ask that you provide documentation to support that statement as well.

I have provided documented proof that the purpose of the tang is dual, that of driving and removal. I have also provided documented information proving that other manufacturers supplement the Morse taper by adding external driving features. I have asked that anybody who cares to refute this provide information. It is as simple as that.

J Tiers
02-11-2008, 09:46 PM
As far as I am concerned, the tang is a secondary issue. I continue to think it is not a good idea to have the tang take any significant part of the torque, and also have evidence (already mentioned) that the friction is surely capable of the full torque.

The "intent" of the tang may be to take some of the torque. Meaning that it was originally intended to.

I'll happily "admit" that, in the sense of "opening the door" to the idea.

Happy?


In any case...........................

A certain amount of vituperation has surrounded the chance that the items originally mentioned as "probably defective" might not be so, and that the cheap jerkl who started the thread is whining about nothing, without evidence.

I think it has been established that in fact they are "defective", and not just a little bit "defective", but "probably" (meaning that the likelihood is pretty significant) outside of "spec" by several times the maximum tolerance.

So, despite the vast improvement in the "finish" part of these Indian products, the "fit" part continues to need some work, at least in this particular case.

lazlo
02-11-2008, 09:55 PM
A certain amount of vituperation has surrounded the chance that the items originally mentioned as "probably defective" might not be so, and that the cheap jerkl who started the thread is whining about nothing, without evidence.

I'm not sure how this discussion descended into topic of the Morse Taper tang. But I think, based on what you described, that you got a morse blank with the taper ground too shallow, and there's nothing that's going to fix that. I'd ask for a replacement.

By the way, I mentioned earlier that the Indian Morse blanks that I got from KBC tools were "Bayard Industrial" -- with a blue and yellow box. Is that, by any chance, what you got?

J Tiers
02-11-2008, 10:52 PM
Nope, these were nicely bagged, and in individual blue boxes, but they are marked "Victor Machinery", which is the US vendor name.

I'll probably drop them a note mentioning that the parts are bad...... but the cost isn't enough to bother returning them for credit. I've done that with ENCO and it cost me a big chunk of the purchase price..... cheaper to toss it in the steel scrap.

I've had good luck with Victor in the past, I hate to see that going bad. This is the second item in a year or so that has been well out of spec.

I kind of expect some "fallout" with Shars, Enco, Grizzly, CDCO, Kitts, and the other frankly "far east" importers. But Victor used to be good stuff at a good price, generally Poland-made.

wierdscience
02-11-2008, 11:03 PM
Okay may as well join it so here goes-

One lathe which is older and American has no provision for a tang slot in the tailstock barrel,it will if provoked slip it's arse off that's the old Hendy.

Other not so old Itailian lathe has a tang slot which is on a #6 taper.

Every Asian built lathe I have ever used along with every European lathe I have used had a tang slot in the barrel.Every American lathe I have used save one was blank.Maybe not having one is just an American thing???

I can also tell you that tang slots in tailstock barrels have nothing to do with removal because you don't need a drift to do so it is the same process as any lathe without a slot.

I can also tell you that the tang does help drive the tool until the shank seats.Reason I know this is because even if you manage to lift a 3-1/4' drill bit that's close to 24" long onto the lathe by yourself you will have trouble slamming it home to a seat manually.

Most drill tangs and chuck tangs are soft,most reamer tangs and some adapter tangs are hard.I know this because our Leland Gifford has had the tang slots "bored" out by a tang when the taper slipped.

So are there any real standards?I don't think so.it seems country of origin or the random feelings of a manufacturer have more to do with it.

Back to the original problem,what about the radius on the tang's shoulder where it meets the shank?That was the source of the problem on several occasions when I had problems with import mt adapters.

aostling
02-12-2008, 01:18 AM
http://mysite.verizon.net/vzeehv3p/rollers.jpg

The rollers are on fixed axles, separated by a fixed distance, and rotate as shown - the speed doesn't matter so long as it isn't too slow. The coefficient of friction between the rollers and the board sitting loosely on top of them is f, and the board is of mass M. The board will oscillate along the x (horizontal) axis. Derive the equations of motion in terms of f, M, and the distance between the rollers, and solve for the frequency of oscillation.

I'm not going to do the math here; the idea was just to demonstrate "fun with friction."

A nice puzzle, which I intend to tackle tomorrow. Will I find a differential equation? Linear? I am intrigued.

Evan
02-12-2008, 04:32 AM
I find your references to my memory and vision insulting. If that is the only ammunition you have left please refrain from replying.

And I find your deliberate attempt to reinterpret what I said as something else equally insulting. You know precisely what I meant and I made it clear. You are up to your old habit of pretending obtuseness for the sake of argument.


I have provided documented proof that the purpose of the tang is dual, that of driving and removal.

No, what you have is documented opinion. I have experience, not opinion.

JCHannum
02-12-2008, 06:51 AM
It is very difficult to reinterpret a five word statement. Accusing me of obtuseness whether real or pretended is simply another insult, and merely degrades your position.

You are right of course, the limited experiences of an ex-Xerox repairman should always be taken over that of industry experts, instructors and manufacturers. We all know that and it is silly to question it. I stand corrected and cede the argument.

Evan
02-12-2008, 07:46 AM
It is very difficult to reinterpret a five word statement.

Yet you manage. And you are the one that has repeatedly accused me of extracting quotes from your postings without the appropriate context. Sound familiar? Incidentally, Xerox has/had the finest training in the industry. Many of the courses can be counted as credit toward an engineering degree.

oldtiffie
02-12-2008, 07:58 AM
Is there any chance of the protagonists packing it in and calling it quits or "square"?

Or alternatively, if you really MUST carry on with this, please do it by/on PM.

J Tiers
02-12-2008, 08:06 AM
"Experts" say many things........

"it is impossible for a bumblebee to fly".

"Powered flight is impossible"

"A man will NEVER travel to the moon"

"Don't bother with way oil, just use Rislone and 20wt, with a bit of bar and chain oil"........

or my favorite of all time, apparently spoken by an old guy who probably was tired of answering questions.... "don't use any way oil at all, it just collects dirt that will ruin the ways. The lathe should be operated with the ways absolutely bone dry"

So the advice of an "expert" is fine. But unless it is tested against reality, it may have little validity.

Some things are better "tested" in "thought experiments", of course, as confirmation of the expert advice, if forthcoming, is likely to damage the test subject........... Probablility theory with regard to certain "one -out-of-six" chances come to mind..........

I suggest that you all go your ways in peace, muttering like "bag people" if you simply must do it. Or if that is insulting to you, consider that you are muttering like Galileo instead.

Either way it won't bother us. After all, we won't hear it. :D

Please. You are bothering those who can't stand not to read it, but who are then offended when they do.

Evan
02-12-2008, 08:12 AM
"it is impossible for a bumblebee to fly".

You are gonna get me going Jerry. :D

What they proved is that a bumblebee cannot GLIDE. Sure enough, they can't. Of course the reporters became confused on the details and the rest is history.

aostling
02-12-2008, 03:13 PM
A nice puzzle, which I intend to tackle tomorrow. Will I find a differential equation? Linear? I am intrigued.

Took me a little longer than it would have done when I was in engineering school, 45 years ago! It's interesting that the frequency of the beam oscillations is independent of its mass, and depends only on the coefficient of friction f, the local acceleration of gravity g, and the half distance between the rollers L.

I'll let somebody else solve for the amplitude.

http://i168.photobucket.com/albums/u183/aostling/IMG_0005-2.jpg

lazlo
02-12-2008, 05:28 PM
Wow, you really did study engineering Allan -- you used real engineering paper, and even signed the top like every engineering fundamentals student was taught. :D

We were also required to put the class title and our social security number underneath the date -- that was in the days before identity theft :)

JCHannum
02-13-2008, 03:51 PM
Having thus far resisted in replying to the latest posts, I succumb to temptation.

I was gone all day yesterday attending an auction where, among many other things a 17" X 58" Clausing Colchester lathe with flats in the tailstock barrel for some strange reason.

I must, firstly, apologize to Evan. It was foolish of me and others to question him and refute his expertise by offering paltry, opinionated information from pundits and exhibiting examples of manufacturers' attempts to employ the MT tang to add to the driving force over the one hundred or so years of it's existance. In light of his experience with a 9" South Bend lathe, all other reason fails. I cede the argument to his wisdom and experience. I am abashed and am man enough to admit my foolishness. Please forgive me.

I do, however, take exception to his statement accusing me of taking his words out of context. I not only directly quoted the statement in question, and explained it's pertinence to the context of the discussion, I cited the entire post, recapped it and responded to each separate topic covered in that post.

I find it very interesting and valuable at this time and stage of the economy to find that textbooks are of no value as a source of information, merely offering opinion as it seems. With the recent spate of extreme cold weather and the current high energy costs, I find myself comfortably basking in the warm glow of the fire fueled by my reference library. It will carry us through the winter I am sure.

Pete H
02-13-2008, 05:47 PM
Thanks for the heads-up about Victor. I was going to order some stuff from them, now I'll be super-careful that it's right. -Pete

oldtiffie
02-14-2008, 07:24 AM
I rather hope that it is safe for people to either put their heads above the trenches or better still to come out and stay out.

If that is the case, could or would they please address the basic intent and topic of this thread and my following paragraph.

I have yet to see, and would appreciate, a definitive method of accurately measuring/checking the taper and whether it is consistent (ie. no "bumps, "dips" "bends" or deviations) throughout its length.

JCHannum
02-14-2008, 07:35 AM
I have yet to see, and would appreciate, a definitive method of accurately measuring/checking the taper and whether it is consistent (ie. no "bumps, "dips" "bends" or deviations) throughout its length.
I believe I touched on that when I referred to the use of a sine bar, Jo blocks and height gage. Add a DTI of the desired resolution and and conduct the measurement on a surface plate. Care must, of course, be taken to assure the readings are taken on the high point of the taper.

J Tiers
02-14-2008, 07:57 AM
The "bumps, dips, or deviations" is a lot harder than the basic determination as to whether the two ends are consistent with the correct taper.

The "deviations" part is the worst, since you are trying to prove a physical surface conforms to a theoretical truncated conical surface. Bumps and dips can be found, if not quantified, by comparison to a known mating surface, by bluing-up, etc.

But that does not, as you pointed out earlier, give a number.

The surface may be bumpy. The surface may be out of round. The surface may be perfectly circular at every diameter, but those diameters may not have their centers on one axis. There are innumerable possible errors, and only one possible correct surface.

The general reference appears to be the axis. The desired surface is a series of infinitesimally wide "hoops", each of a different diameter, but each perfectly circular and centered on the axis.

A method of comparison of dimensions to that axis is therefore suggested. Mounting on centers is one way of holding the part for comparison, as it may be turned, and moved axially past a measuring device. (errors of center holes may, I think, be fairly considered to be errors in the part, as they were used as a reference to generate the surface)

An "exploring probe" is used to examine the location of the surface at each point with reference to the axis. This might be a suitable point attached on the end of an indicator spindle.

Then the part can be rotated to compare every point on the "hoop" surface with the axial reference (the holding centers). And it may be moved axially to examine successive "hoops" on the surface.

Errors are accuracy of centering of rotation on the axis, accuracy of axial movement, and the obvious accuracy of the measuring probe system.

oldtiffie
02-14-2008, 08:24 AM
I have yet to see, and would appreciate, a definitive method of accurately measuring/checking the taper and whether it is consistent (ie. no "bumps, "dips" "bends" or deviations) throughout its length.



I believe I touched on that when I referred to the use of a sine bar, Jo blocks and height gage. Add a DTI of the desired resolution and and conduct the measurement on a surface plate. Care must, of course, be taken to assure the readings are taken on the high point of the taper.

Thanks Jim.

Indeed you did - many thanks.

I have included a pic with 2 sketches which indicate the basics of the approach.

It is the "semi-angle" in the second sketch that we are after - is it not?

The first diagram is very basic and does not show how to retain the axis of the job parallel to the edges/sides of the the sine bar so as to ensure that the job centre is not "skewed".

The second digram is quite correct in itself as the "hooks" on the bases of the centre holders keep the centre line parallel to the edges of the sine bar and so avoid the "skew". It may not be within the resources of a typical HSM-er or his shop. Many HSM-ers do not have access to or use of a good surface plate or sine bar, slip guages or locating accurate centres. I have them all. I would use the centres from my Tool & Cutter grinder as these have accurately located and fitted keys to locate to the grinder bed. I would use my magnetic sine chuck to hold the centres.

Provided that the centre holes at both ends of the work under test are OK then that set-up will allow the job to be rotated as well which should sort out all details - including any errors.

I am not being a smart-ar*e here - and I am not inferring that anyone said I was/am (probably true though!!) but I am just trying to point out how difficult it can be to sort these seemingly apparently "minor/easy" problems out.

http://i200.photobucket.com/albums/aa294/oldtiffie/taper_and_sine-bar1.jpg

oldtiffie
02-14-2008, 08:32 AM
The "bumps, dips, or deviations" is a lot harder than the basic determination as to whether the two ends are consistent with the correct taper.

...............................................

.................................................. ..

A method of comparison of dimensions to that axis is therefore suggested. Mounting on centers is one way of holding the part for comparison, as it may be turned, and moved axially past a measuring device. (errors of center holes may, I think, be fairly considered to be errors in the part, as they were used as a reference to generate the surface)

An "exploring probe" is used to examine the location of the surface at each point with reference to the axis. This might be a suitable point attached on the end of an indicator spindle.

Then the part can be rotated to compare every point on the "hoop" surface with the axial reference (the holding centers). And it may be moved axially to examine successive "hoops" on the surface.

Errors are accuracy of centering of rotation on the axis, accuracy of axial movement, and the obvious accuracy of the measuring probe system.

Thanks again JT.

As is very the case, you have got it right and have explored for and have identified the salient points.

I have posted pics in my previous post - copied here - which I hope illustrate the very good points you make.

http://i200.photobucket.com/albums/aa294/oldtiffie/taper_and_sine-bar1.jpg

hitnmiss
02-14-2008, 09:00 AM
12 pages of "Mines bigger than yours"

!

I don't know what's sadder, the fact that you guys wrote 12 pages or that I read them!

oldtiffie
02-15-2008, 07:09 AM
12 pages of "Mines bigger than yours"

!

I don't know what's sadder, the fact that you guys wrote 12 pages or that I read them!

Thanks hitnmiss.

Good "get back to reality" post.

Served me right for being a "smart-ar*e" and a "big-noter"/"skite".

I guess I deserved and needed that.

So - how to do it with stuff that can be found in many/most HSM shops?

It took a bit of looking around for tools and materials and then getting back to first principles and re-focusing on the job at hand - checking the taper reasonably accurately.

Here we go.

There are too may pics to post in one go - even with multiple successive posts, so I will do it in one post using direct links to the pics and readers can "click" them (or not) to suit themselves.

The principles here were and are sound but far too expensive for may HSM shops:
http://i200.photobucket.com/albums/aa294/oldtiffie/taper_measure-set-up/taper_and_sine-bar1.jpg

I will use my HF-45 mill and 2 rotary tables - "Rotabs" - (6" and 8"). The 6" has a 7 1/2" lathe face-plate that I modified to suit my lathe and rotabs.

Both rotabs are calibrated to read to 5 minutes direct and at least 2 by interpolation. The test sheets show a maximum error of 1 arc minute.

The 8" has a 10" face-plate that is part of the rotab package.
http://i200.photobucket.com/albums/aa294/oldtiffie/taper_measure-set-up/HF45-6.jpg

My basic idea was to set the MT sleeve and an MT with a chuck "Jarno" taper up to be suspended/fixed between centres in a rotab.

The centres were made from spare 18mm (3/4") Cold-rolled steel rod that I had. I set them up in the lathe to less than 0.0002" (2 "tenths") Total Indicated Run-out (TIR) with my TDI which is calibrated to 0.01mm (0.0004") and turned the 60 degree tapers. So maximum "run-out" as measured was 0.0001"

The rotab was set to indicate zero run-out with/along the 20mm centres OD's with the TDI at centre height.

The work-pieces were to be fitted between the centres to be a light turning fit with no "slack" or "end-float" .
The rotab reading was to be recorded at that setting (setting 1).

The rotab was to be rotated until there was zero deflection on the TDI as it was run along the taper by using the mill table "X" lead-screw. This setting was recorded (setting 2).

The difference/s between the settings was the taper of the work-piece (ie half the included angle) as in the sketches in the first link.

This worked very well. No clamps were needed. I could have used small bags filled with lead shot over the centres to hold them.

Checking concentricity and/or run-out was very easy as well.

In retrospect, I would have done better with the centres made from 2" CR stock - mainly for centre height and weight (for stability).

http://i200.photobucket.com/albums/aa294/oldtiffie/taper_measure-set-up/Taper_measure_set-up1.jpg

The next method was a variation on the first. I used 2 vee blocks (matched set) on the rotab table. The vee blocks were aligned by dropping either a straight round bar or a piece of straight extruded brass angle stock into the vee blocks. The alignment was excellent.

The centres were placed in the vee blocks and the work was suspended easily without clamping. The blocks did not move on the rotab either. If they had, I would have used paper between the blocks and the rotab table.

This too worked very well.

http://i200.photobucket.com/albums/aa294/oldtiffie/taper_measure-set-up/Taper_measure_set-up2.jpg

The next pic is a variation on the previous pic. but is set up on the 6" rotab using the brass angle to both keep the vee blocks in alignment as well as providing a very successful extension of the "V" to rest the centres in/on to support the work piece.

http://i200.photobucket.com/albums/aa294/oldtiffie/taper_measure-set-up/Taper_measure_set-up4.jpg

The next pic is another variation making use of the larger (7 1/2") angle plate on the 6" rotab without the brass angle.

http://i200.photobucket.com/albums/aa294/oldtiffie/taper_measure-set-up/Taper_measure_set-up5.jpg


The next pic is a variation of the previous pic except that the brass angle is used.

http://i200.photobucket.com/albums/aa294/oldtiffie/taper_measure-set-up/Taper_measure_set-up6.jpg

The next pic is of using the centres in the top of the "T" slots in the mill table. It was surprisingly accurate and would work as/for a quick check for concentricity for anything that could be held between centres.

http://i200.photobucket.com/albums/aa294/oldtiffie/taper_measure-set-up/Taper_measure_set-up7.jpg

I hope this helps.