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lane
05-20-2009, 07:33 PM
Just thinking to day for lack of any thing better to do.
If I had a million dollars for every time I saw the spindle bearings replaced in a mill at any shop, I have worked in in the past forty years. I would still be poor.
Never . So not having much to do I went around to all 6 mills I have at my disposal at work with a tenth indicator . checked in side the spindle at two spots about 3/4 inches apart . Guess what according to the members here they are all wore out. But I do precision machine work with them daily. the worst was .002 run out in 3 machines .00005 in 1 .0015 in one and .0003 in my brand new machine.. \
Now is any body going to replace them No. the work just fine. If you ask management they will say . Well does the machine still run are not. If the motor will make the cutter turn run it till it want ,then we will see about fixing it.
About a week ago I showed the boss the surface grinder. boss the spindle bearings are wore out . Just listen i`m hollowing at him so he can here over the noise of the bearings singing. Next I turn it off and say grab the pullt around back and turn it and fell the balls go bump bump bump .
He said, but want it still grind the finish looks good to me . And it does and I have a mirror finish ,can see my self in it. but the bearings are still wore out and will stay that way till it wont grind any more.
So just because your mill is not brand spanking new and you have .002 run out in the spindle DO NOT worry about it. It will still cut. and is probably an better mill than you are a machinist.
It`s nice to have all brand new toys . but most good machinist have never seen any.
Any body can run a new machine. It takes a real machinist to run a wore out one.
I know you are saying but I do not clam to be a machinist , just a hobbyist
Well I say learn to live with what you got and make it do. those new $300.00 dollar bearings are not going to make your parts any better.

Now you all can all jump on me I`m fair game. But I speak the truth.

Seastar
05-20-2009, 07:45 PM
Amen!!!
Bill

JCHannum
05-20-2009, 08:10 PM
I have to agree. Way too much time is spent agonizing over spindle runout, bed wear and other trivialities and fantasizing over being able to machine to some imaginary level of precision.

I can quite truthfully say that I have never put an indicator on either my lathe or milling machine spindle, and I have no intention of doing so. They are more than capable of turning out work that is well within the acceptable limits of those type of machines.

Carld
05-20-2009, 08:13 PM
Lane, I agree, all the job shops I worked in had old BridgePort and knockoffs of them and they were used hard. For instance one shop used flycutters at 1000+ rpm, .050" DOC at moderate to heavy feed in steel and the bearings never had to be replaced in 10 years of use I know of. I can only remember replacing bearings in a BridgePort one time and it was VERY old and beat up but it sure cut nice after that. I have used mills and lathes in shops that many would think should be in the junk yard but they still turn out good work. They won't do NASA grade work for sure but they do good work to spec.

madman
05-20-2009, 08:18 PM
I have aNEW bridgeport circa 19061 serial number 370 LOL thats gotta be old. I use it every day and do some stupid jiobs, tolerances .001 over 12 inches and stuff? It seems ok and i DO KNOW those first mills i have worked on are aLL jUNK.

Bmyers
05-20-2009, 08:18 PM
I started enjoying this hobby a lot more when i stopped worrying about everything being within .001 unless I really need it.

Evan
05-20-2009, 08:21 PM
A commercial shop and a home shop are two very different entities. Any commercial shop that ignores preventive maintenance will, at the very least, be much less profitable. Sure, the grinder might still produce a decent finish. But, those bearings will fail and if it happens in the middle of a critical job they are going to turn out to be very expensive bearings.

A home shop machinist has a different motivation to practice preventive maintenance. He most likely doesn't view his machines as expendable and probably not only wants but needs to minimize the cost of operation. The easy way to do that is to replace parts when they first show signs that they are near end of life. It really isn't wise to run a machine until the bearing balls crumble and spin the races thereby destroying the seats.

lane
05-20-2009, 08:53 PM
A commercial shop and a home shop are two very different entities. Any commercial shop that ignores preventive maintenance will, at the very least, be much less profitable. Sure, the grinder might still produce a decent finish. But, those bearings will fail and if it happens in the middle of a critical job they are going to turn out to be very expensive bearings.

All so true But you would be surprised at how common that is . Do not fix till it is BROKE.

A home shop machinist has a different motivation to practice preventive maintenance. He most likely doesn't view his machines as expendable and probably not only wants but needs to minimize the cost of operation. The easy way to do that is to replace parts when they first show signs that they are near end of life. It really isn't wise to run a machine until the bearing balls crumble and spin the races thereby destroying the seats.

I agree. but all I am saying is most folks worry about things that do not matter that much. If the had a 10 EE are Hardinge HLV they would not have the skill to get the full use from it. Are any other machine for that matter.
I know you have done wonders with your SB I have seen your work. I have one too and have done things with it good machinist said could not be done. . But that just goes to show their are exceptions.

J Tiers
05-20-2009, 09:43 PM
Hobbyists worry about that stuff because they can.

People who make money at it don't have time to worry about that stuff, until and unless it shows up in the work, AND it can't be worked around.

I HAVE in fact put indicators on lots of machines and machine parts....... I do it when I see some odd and undesired things that I think might be due to problems the indicators might show up. In a couple cases I was right, in others I was wrong.

Having the OPTION to check stuff like that when you need to is good. But if you don't see an issue, then measuring stuff like that, just because, is basically like a white glove inspection. The crapper will still work if there is dust on top of the door frame, and your machine will work with a thou "too much" runout. Maybe you will have to cut the feed a bit on a finish pass... OK.

I wish I had a half buck for every time someone has been certain that their spindle was bent and were sure that "fact" makes their lathe just scrap metal. 19 out of 20 have had other problems, problems with the indicator setup, with dings, swarf, chuck runout, etc.

It seems to be a law of hobby people (and others) that if there is a problem with the machine, the (hobbyist) owner will zero in on one of the most expensive parts of the machine as the problem. Typically the spindle or the bearings.

There are at least three things wrong with my Logan, but it works fine, and those things can be worked around.

lakeside53
05-20-2009, 10:09 PM
Yep... my head spindle needs grinding, my tables sag and I have 50 thou backlash on the X.. I barely notice it although occassionally it gets my attention when climb milling:D

yes... I'll fix it all one day, but for now I'm too busy making chips to even paint the other two BPs which are all over my workshop in pieces.

Oh... I did replace the spindle bearings... they were growling from rust. And... all three of my BPs were from shops that used them until they died of neglect.. so... you could say the condition I got them in was how they were the last time the power was turned off.

lazlo
05-20-2009, 10:16 PM
Just listen i`m hollowing at him so he can here over the noise of the bearings singing. Next I turn it off and say grab the pullt around back and turn it and fell the balls go bump bump bump .
He said, but want it still grind the finish looks good to me . And it does and I have a mirror finish ,can see my self in it. but the bearings are still wore out and will stay that way till it wont grind any more.

If that grinder's bearings are that bad, it'll leave a decorative finish, but it won't be flat.

That's why you often find grinders for so cheap -- the bearings are shot, and it's cheaper to buy a new machine than to rebuild the spindle. :)

Walter
05-29-2009, 06:50 PM
Just thinking to day for lack of any thing better to do.
If I had a million dollars for every time I saw the spindle bearings replaced in a mill at any shop, I have worked in in the past forty years. I would still be poor. Never

Hrm, I have the same problem.


So not having much to do I went around to all 6 mills I have at my disposal at work with a tenth indicator . checked in side the spindle at two spots about 3/4 inches apart . Guess what according to the members here they are all wore out. But I do precision machine work with them daily. the worst was .002 run out in 3 machines .00005 in 1 .0015 in one and .0003 in my brand new machine.. \
Now is any body going to replace them No. the work just fine. If you ask management they will say . Well does the machine still run are not. If the motor will make the cutter turn run it till it want ,then we will see about fixing it.

We run a 60's - 70's era Westbury/Induma 1S, let me tell you about it.

When someone (god gnows who) snapped off the table locks, they then resorted to using the Gib adjusting screws to lock the table.

Knee lock.... non existant.

Original power feed removed, lead screw and handle flopping around unsupported.

Retainer for the quill feed speed handle, learned that was missing when the handle came off as I was doing a job. (had depth stop set so no damage).

I'll stop my list there, it's longer but you get the idea. All has been fixed / repaired now without spending a dime on materials, just using up drops and scrap.

A few weeks ago I built a die set for custom grinding setup meant to do small parts in batches (stacked). This die set was built with pressed pins, plain removable bushings. Works like a charm. All of it was done on that Induma. The point is simple, anyone willing to learn to work with what they have can do some amazing things. Quite honestly I was surprised the die set worked out as well as it did, I expected more headaches.


About a week ago I showed the boss the surface grinder. boss the spindle bearings are wore out . Just listen i`m hollowing at him so he can here over the noise of the bearings singing. Next I turn it off and say grab the pullt around back and turn it and fell the balls go bump bump bump .
He said, but want it still grind the finish looks good to me . And it does and I have a mirror finish ,can see my self in it. but the bearings are still wore out and will stay that way till it wont grind any more.

I won't even discuss our old manual Reid surface grinder except to say that I pulled the table off and did some frosting so that the table didn't have to be lifted every few passes to relieve the stiction. I'd have approached it differently, but I had no option as the machine is used every day without fail and cannot be down.


So just because your mill is not brand spanking new and you have .002 run out in the spindle DO NOT worry about it. It will still cut. and is probably an better mill than you are a machinist.
It`s nice to have all brand new toys . but most good machinist have never seen any.
Any body can run a new machine. It takes a real machinist to run a wore out one.
I know you are saying but I do not clam to be a machinist , just a hobbyist
Well I say learn to live with what you got and make it do. those new $300.00 dollar bearings are not going to make your parts any better.

Now you all can all jump on me I`m fair game. But I speak the truth.

As an employee I do care, and care greatly that the machines that help me earn my living are well cared for. I do not expect perfection, it's business and barring a serious failure, I do regular PM, I fix whats broken, and adjust what needs to be adjusted that's all I can do because not one damn dime in this economy is getting spent on parts unless I can't build them. I'll also admit that I find myself pushing very hard with my own tools at home, moreso from a compulsive need to find that elusive perfect set of adjustments *grin*. I have spent days at home chasing down an odd vibration, or noise in a machine. Why... Because I actually enjoy it.

That said, I'm off to adjust my muffler bearings, they're making some noise under hard acceleration.

Fasttrack
05-29-2009, 07:05 PM
Keep in mind that a lot of that concern regarding spindle bearings, worn ways, etc comes from newbies like myself. Without having the expierence or skill of you veteran machinists, it makes it hard to determine which machine(s) to buy. We think about it like buying a car - you always hear horror stories about a car with sawdust in the tranny or etc that only has maybe 5000 miles left in her before blowing up. We don't want to drop a bunch of "play" money on a machine that is so worn out that it can't be used at all.

Add to that a general lack of skill (from lack of practice) and those old sorry machines can be quite intimidating.

But I agree. Once I got some time in running old machines, I found that even the reall sad looking ones worked just as well, if not better, (for my purposes) than newer machines.

John Stevenson
05-29-2009, 07:09 PM
Lane i have said this for a long time, even posted it on here a few times, even got flamed for it as well.

Mainly it was posted under ABEC 7 rules of engagement :D do a search ans you will find many that didn't agree with what I said.

I'll repeat it here ABEC7's will be better then standard bearings - fact but once fitted they start to wear. initially that wear will not be noticable or measurable but at some point it will be equal to a standard bearing.
After that the wear increases until it becomes measurable.

What we don't know is these three points, from ABEC 7 to standard and from Standard to measurable.

My argument was that standard bearings will suit the home shop because the distance from standard to measurable will probably be greater than the users remaining life span.

Now it looks like because you have said it people agree with you, when I said it they didn't :rolleyes:

I even had J Tiers telling me that lubricated bearings don't wear, it's only foreign bodies that cause wear ? [ so a ball in a ball race revolves with no skidding because of different diameters in mesh at the same time ? ]

I feel this will be an interesting thread. ;)

.

J Tiers
05-29-2009, 08:08 PM
I'm a great proponent of using what you have...... (if you mix Swede with Irish and French, the result will spend less money than a scot).

If the difference will be significant, spend the money, it's cheaper to spend a little bit more once, than to spend a little less twice. If no big difference will be made, don't spend the money. Mostly, I don't.

I see a lot of folks saying stuff like "its only a hobby machine, it don't have to be that good". That's stupid, actually, they don't know what the other guy's hobby IS. It might be worth it to him. Mostly it isn't, but there are exceptions.

I already noted the tendency for newbies to assume the most expensive part is complete toast...... And to assume they need the best possible accuracy, so they come to check out a machine with a box of indicators.

Lane's right..... get over it, and use whatcha got.....

BTW, JS, since you think I'm such a total prat that it was worth trying to ridicule me specifically, tell me why THE industry way to determine the remaining life of a BB is to LISTEN to it....... Yes indeedy, Johnny, it's to see how much fatigue spalling is in the races......

neither you nor I was born knowing anything, let alone about bearings, The bearing companies told me that BBs don't wear, that they fatigue out first (assuming they are loaded well into their expected range).

So blame them, not me, Johnny-boy. My only crime here is actually reading their app notes.

lazlo
05-29-2009, 08:17 PM
John, Lane's saying that he does good work on machines with worn-out spindle bearings, and that precision spindles bearings don't make a difference for a HSM'er:


So just because your mill is not brand spanking new and you have .002 run out in the spindle DO NOT worry about it. It will still cut. and is probably an better mill than you are a machinist.

Well I say learn to live with what you got and make it do. those new $300.00 dollar bearings are not going to make your parts any better.

You're saying something very different: that precision spindle bearings are much more accurate, but that they wear so fast that they'll be non-precision bearings quickly anyway, so a HSM'er might as well just start with non-precision bearings.


I'll repeat it here ABEC7's will be better then standard bearings - fact but once fitted they start to wear. initially that wear will not be noticable or measurable but at some point it will be equal to a standard bearing.

What we don't know is these three points, from ABEC 7 to standard and from Standard to measurable.


There are thousands of precision machine tools with their original bearings that demonstrate otherwise: almost all 10EE's, Deckels, et al, have > 50 year old bearings and still hold incredible precision. Jerry's point was that the primary wear factor on bearings is grit abrading the balls and races. If you keep them clean, precision bearings will last a lifetime.

In any event, I think you both (Lane and John) know that you're not going to change anyone's mind here about this: you're either happy with the bearings you have, or you're not. If you happen to have precision spindle bearings, you probably have a strong notion that you need that accuracy ;) Judging from the people who have installed common bearings on their machines, they fiercely defend that they work great (and usually add that they're not making parts for NASA :D).

By the way, you can quantify the difference in runout between precision spindle bearings, and ungraded bearings: ABEC-7 radial runout is 1 tenth. Add the bearing bore tolerances and the spindle sleeve runout, and you get to the 2 - 3 tenths runout that's typical on a modern machine tool.

An ungraded, ABEC-1 bearing has a runout spec three times that: 3 tenths. Add the bore tolerance and the spindle sleeve runout, and you're into 6 - 9 tenths (almost a thou) runout. Which, not coincidentally, is the runout spec on the Mini-Lathe, which uses common bearings.

http://i164.photobucket.com/albums/u15/rtgeorge_album/ABEC3.gif

John Stevenson
05-29-2009, 08:22 PM
BTW, JS, since you think I'm such a total prat that it was worth trying to ridicule me specifically, tell me why THE industry way to determine the remaining life of a BB is to LISTEN to it....... Yes indeedy, Johnny, it's to see how much fatigue spalling is in the races......

neither you nor I was born knowing anything, let alone about bearings, The bearing companies told me that BBs don't wear, that they fatigue out first (assuming they are loaded well into their expected range).

So blame them, not me, Johnny-boy. My only crime here is actually reading their app notes.

Whoa, who said you were a total pratt ? Is there something in the water this week I've had Norman chewing away at me on 5 groups.
I'm repeating what you told me, go back and search it before you pop off.

I said you told me [ not the bearing companies - YOU ] that BB's don't wear.

Now you are saying its the BB who tell you they don't wear but fatigue.
So what causes them to fatigue ?

look at a bearing you have the ball revolving at one speed, the inner driving it and the outer track is traveled at a different rate because the ball is a constant diameter.

Add to this parts of the ball are in grooves of differing diameters in both the inner and outer so some skidding takes place but this cannot cause wear ?

So technically if they are all running at the same speed - in mesh so to speak they could exist with the barest minimum of lubrication and work but what happens if we deny that bearing lubrication.
It gets hot [ friction ] and siezes.

How can friction be developed between 3 matched speed surfaces ?
It can't there has to be a mis match hence friction, rubbing and wear which CAUSES fatigue.

John Stevenson
05-29-2009, 08:34 PM
You're saying something very different: that precision spindle bearings are much more accurate, but that they wear so fast that they'll be non-precision bearings quickly anyway, so a HSM'er might as well just start with non-precision bearings.

Where did I say they wear that fast, I said they wear until they reach standard tolerances. I never gave a time scale in fact i added we don't know the 3 points.
Why can't people read what is written , not what they want to read. Believe it or not this is the 4th time today i have had to reply to a post where a sentence in clear English hasn't been read properly.





There are thousands of precision machine tools with their original bearings that demonstrate otherwise: almost all 10EE's, Deckels, et al, have > 50 year old bearings and still hold incredible precision. Jerry's point was that the primary wear factor on bearings is grit abrading the balls and races. If you keep them clean, precision bearings will last a lifetime.

Very true but at some point they will waer, even with regular lube changes and cleaning to remove grit etc the play will develop.
Where does the foreign bodies come from on say a shaft with just two sealed bearings, no gears etc to thow off parts.
It's got to come from one or more of the revolving bodies.



In any event, I think you both know that you're not going to change anyone's mind here about this: you're either happy with the bearings you have, or you're not. If you happen to have precision spindle bearings, you probably have a strong notion that you need that accuracy ;) Judging from the people who have installed common bearings on their machines, they fiercely defend that they work great (and usually add that they're not making parts for NASA :D).
No it will always be split, Lane is saying you can use worn bearings, I am saying that it's not necessary to go to super precision because of Lanes findings.


By the way, you can quantify the difference in runout between precision spindle bearings, and ungraded bearings: ABEC-7 radial runout is 1 tenth. Add the bearing bore tolerances and the spindle sleeve runout, and you get to the 2 - 3 tenths runout that's typical on a modern machine tool.

An ungraded, ABEC-1 bearing has a runout spec three times that: 3 tenths. Add the bore tolerance and the spindle sleeve runout, and you're into 6 - 9 tenths (almost a thou) runout.

http://i164.photobucket.com/albums/u15/rtgeorge_album/ABEC3.gif
By standard I was meaning what your table calls ABEC 3, to me ABEC 1 are Chinese motor bearings.

I told you it would be an interesting post :D

.

lazlo
05-29-2009, 08:50 PM
Where did I say they wear that fast, I said they wear until they reach standard tolerances. I never gave a time scale in fact i added we don't know the 3 points.

Isn't that the whole point of your argument? You say that ABEC-7 bearings are much more accurate than common (ABEC-1) bearings, but that they wear out of spec. I have to assume you mean they wear quickly, otherwise your argument would be that my grand children don't need to worry about precision spindle bearings :)

But there seems to be a big flaw in your argument: you're advocating either ungraded bearings, or ABEC-3 (a tweener between precision spindle bearings and ungraded bearings). But whether you believe a bearing wears fast or slow, the non precision bearing will wear at least as fast as a precision bearing, probably faster -- since the balls on a common bearing aren't as round, the races aren't as smoothly honed... So the ungraded bearing will have mediocre runout to start with, and wear worse just like precision bearings.


Lane is saying you can use worn bearings, I am saying that it's not necessary to go to super precision because of Lanes findings.

Lane's a master tool and die maker. Look at his work -- he could make that precision workhead (http://bbs.homeshopmachinist.net/showthread.php?t=23242)out of a ball peen hammer and a set of Harbor Freight chisels. :D
http://sites.google.com/site/machinistsite/TWO-BUDDIES/lanes-home/tooling/workhead-project/LWorkhead2.jpg

By the way, I notice that Lane used ABEC-7 bearings in his sensitive workhead ;)


By standard I was meaning what your table calls ABEC 3, to me ABEC 1 are Chinese motor bearings.

Aye, real ABEC-3 bearings are definitely a great compromise in price/performance, with substantially better runout than common, ungraded (ABEC-1) bearings. You made a point in a previous bearing discussion we had that, due to improved manufacturing tolerances, quality Western or Japanese bearings are typically one grade up from their spec'ed grade. So a modern ABEC-3 bearing is probably close to ABEC-5 tolerances.

J Tiers
05-29-2009, 09:09 PM
Lazlo's point is also brought up by the maker's, who claim that more precise parts in the bearing mean slower onset of failure.

And, don't forget, the ABEC stuff basically means how well-made the parts are...... I've never seen an ABEC spec on the performance of the finished part......

It's basically an assumption (a good one, likely) that more precisely round and centered races mean the bearing will let the spindle rotate closer to "centered".

It is NOT as if the cutter won't cut if the spindle is nutating and spinning off center as a whole. The argument might be made that the finish will be a little better, and the cutter may last a little longer, etc, with super bearings.

But I defy anyone to prove that a bearing that is a tenth or so "less good" is going to make a huge difference in the "precision of your work", (whatever that is). That tenth is about the difference between the highest ABEC rating and the next one down.

And another tenth or so "worse" for an ordinary good bearing........ So the difference between super and ordinary is maybe 3 tenths in the bearing parts........ leading to at worst, maybe 6 tenths in lowest to highest position of the cutter.

And just how much difference does that make if you are working to a basic tolerance of a couple thou? Especially considering that the AVERAGE position is not the highest or lowest.

lazlo
05-29-2009, 09:31 PM
So the difference between super and ordinary is maybe 3 tenths in the bearing parts........ leading to at worst, maybe 6 tenths in lowest to highest position of the cutter.

Agreed -- I think that's what this whole discussion boils down to.

But the bigger point is that this is a hopeless topic -- you're not going to convince a guy who just put ungraded bearings in his Bridgeport spindle that he's increased his runout by nearly 3x :p

If you're happy with your bearings, precision or otherwise, great! If you're not (the bearings whine, you're getting crappy surface finish, ...), you have several options: you can buy ABEC-3/5 bearings really cheap from MSC during their 25/30% off sales. You can also buy that $300 set of ABEC-7/9 bearings that Lane mentions, New In Box off Ebay for $50 - $75 (personal experience, based on the bearing OD).

lane
05-29-2009, 11:23 PM
Yall don`t get carried away again. This was posted about a month ago.
And Please quit referring to me as some kind of super master machinist . I `m just your average Joe Machinist . Better than some not as good as others.

oldtiffie
05-30-2009, 03:50 AM
Lazlo's point is also brought up by the maker's, who claim that more precise parts in the bearing mean slower onset of failure.

And, don't forget, the ABEC stuff basically means how well-made the parts are...... I've never seen an ABEC spec on the performance of the finished part......

It's basically an assumption (a good one, likely) that more precisely round and centered races mean the bearing will let the spindle rotate closer to "centered".

It is NOT as if the cutter won't cut if the spindle is nutating and spinning off center as a whole. The argument might be made that the finish will be a little better, and the cutter may last a little longer, etc, with super bearings.

But I defy anyone to prove that a bearing that is a tenth or so "less good" is going to make a huge difference in the "precision of your work", (whatever that is). That tenth is about the difference between the highest ABEC rating and the next one down.

And another tenth or so "worse" for an ordinary good bearing........ So the difference between super and ordinary is maybe 3 tenths in the bearing parts........ leading to at worst, maybe 6 tenths in lowest to highest position of the cutter.

And just how much difference does that make if you are working to a basic tolerance of a couple thou? Especially considering that the AVERAGE position is not the highest or lowest.

Great post JT.

It should be saved and printed out and nailed to the wall under "Reality Check".

First of all, the class of bearings and run-out in the taper of a mill spindle is not the be-all and end-all of a mill. A DTI (dial test indicator) reading of TIR (total indicated run-out) at any/only one place in the quill spindle taper is not a good indication at all. "Run out" has two components - radial: where the taper is parallel to but eccentric to the spindle axis; and angular" where the axis of the taper describes a cone. Both may be present together. It will take at least two separate TIR readings to sort it out.

The same errors can exist between the end-mill adaptor taper and its internal taper that accepts the collet.

The same applies between the:
- outer tapers and inner bores of each and all collet; and
- the stem (plain section) and cutting edges of the end milling cutter.

All of these errors are potentially additive, subtractive or in between (mutually self-canceling) at the cutting edges of the end-milling cutter.

So, even if the mill is "correctly trammed", the end milling cutter flutes may cut "off-centre" (parallel) or "conically" (tapered cut) or a mix of both when cutting a vertical surface. Further, if the multi-toothed (end-milling) cutter is cutting conically, the apparently "good" trammed cut will not be flat at all as it will be a series of "flats" (at the bottom under the centre of the cutter) and sloped/curved up the sides. Only a single pointed tool such as a fly-cutter can be assured to/of cutting a flat trammed horizontal surface. Don't believe it? Didn't your "Guru/Mentor" tell you? Wasn't it in the books put out by those revered old-time writers? Sorry. Not. Want to prove it? Put it on a surface grinder!! It may not be much at all. It may even be very little, but if that cutter was "bent" and moving in a conical path the "dips" will be there!!!

OK. So I am the smart-ar$e here. What would I do about it? I would leave the end-milling cutter in my MT3>ER-32 adaptor and put it in my work-head (with an MT3 bore/taper) and on my T&C grinder and sharpen the cutter. This will cancel out any errors between the MT3>ER-32 adaptor MT3 taper and the cutter. The MT3 taper in my grinder is very accurate and the MT3 taper in my mull quill spindle is likewise very accurate. So I have eliminated/canceled-out most of my errors.

http://i200.photobucket.com/albums/aa294/oldtiffie/Grinder_work-head_demo/Grind_work-head_demo10.jpg

Most times (99.9%) I don't do that as I just whack the cutter into the collet in the milling adaptor in the mill and get on with it - same as just about everybody else does.

On my lathe, I don't worry too much about any similar "run-out" in my chucks or collets as as soon as I take my first cut, that cut is "true" to the lathe spindle axis.

Surface and T&C grinder wheels? As long as they are dressed correctly they will be OK as they are now "true" to the grinder spindle axis. I do balance my surface grinder wheels but I don't have - and don't need - that facility on my T&C grinders. Given a choice I'd choose a T&C grinder over a surface grinder - in my shop - every time as a T&C grinder works better as a surface grinder than a surface grinder does as a T&C grinder.

As regards grinder spindles in my shop. If the bearings were "gone" (and I mean really "gone" as I agree with Lane here) I'd replace them with whatever my supplier can get that will do the job as I don't use the grinders much at all. Both spindles are relatively low speed and operate under fairly low loads. If I burn out a motor, I will get it re-wound and dynamically balanced as there are some very good re-wind/re-balance shops here. Too many people make far too much an issue of "finish" in surface grinding most times - same applies to cylindrical grinding.

Frankly, I agree with Lane, John S and JT as you have to make the best of what you have as regards tools, machines, materials - and expectations.

So, don't get "wound up" or unduly concerned about the "high level" talk about spindles and bearings as most machines that are running can and will do a very good job in the average HSM shop.

And that applies equally to "Good Old American Iron" as well as the stuff from Asia/China.

Most people here and their machines can do very good work. Don't be intimidated by others. Just use what suits you.

Just don't get "worried" or "wound-up" as most times it is neither needed nor necessary.

Most HSM shops are not "production" shops - but are "hobby" shops.

Just get on and accept things for what they are and enjoy yourselves and your shop.

Circlip
05-30-2009, 05:04 AM
What you seem to forget Sir John is that male bovines are a lot smaller on our side of the pond. :D

Regards Ian.

J Tiers
05-30-2009, 10:05 AM
Surface and T&C grinder wheels? As long as they are dressed correctly they will be OK as they are now "true" to the grinder spindle axis.

Getting way stupid and over-technical, that isn't really true. it IS true for most any practical purpose with decent bearings, and there is really no point in worrying.

But "for completeness" in actual micro-reality, with a ball/roller bearing, there may BE no single "axis of rotation".

This is because the particular set of rolling elements are not all identical. If you are going for the absolute swiss jig borer silly accuracy, you will find another VARYING error as the different sized rolling elements go around the races, and as they pass the irregularities in the races...... They go at a diifferent speed than the races, so there is no constant error, it varies over several spindle rotations, and may not repeat for a while.

That's another secondary effect causing the axis of rotation to move around, at a different rate than due to the races. So there is a *very small* additional wobble that can never be trued-out.

Since none of you have a swiss jig borer, and none of you are MAKING a swiss jig borer (I understand even the swiss don't make them any more), this is "not likely to be an issue"........... (understatement of the year?).

BTW, I understand that much of the concern with this sort of micro-error is not necessarily just about surface finish and precision, but also about ultimate balance and life in extremely high speed spindles, ones spinning at 120,000 rpm or the like. Yet another concern that isn't so likely to be a worry for people here.

John Stevenson
05-30-2009, 10:57 AM
Agreed -- I think that's what this whole discussion boils down to.

But the bigger point is that this is a hopeless topic -- you're not going to convince a guy who just put ungraded bearings in his Bridgeport spindle that he's increased his runout by nearly 3x :p



That's the whole point, according to Lane in the first post and everyone agreed with him that a bit of runout doesn't matter.

The post has gone full circle from runout doesn't mater to it does and you need ABEC 7's to prevent it.

Makes you smile doesn't it, mainly because i could see where this was going, remember my "this will be an interesting post " ?

.

oldtiffie
05-30-2009, 08:50 PM
Originally Posted by oldtiffie
Surface and T&C grinder wheels? As long as they are dressed correctly they will be OK as they are now "true" to the grinder spindle axis.


Getting way stupid and over-technical, that isn't really true. it IS true for most any practical purpose with decent bearings, and there is really no point in worrying.

But "for completeness" in actual micro-reality, with a ball/roller bearing, there may BE no single "axis of rotation".

This is because the particular set of rolling elements are not all identical. If you are going for the absolute swiss jig borer silly accuracy, you will find another VARYING error as the different sized rolling elements go around the races, and as they pass the irregularities in the races...... They go at a diifferent speed than the races, so there is no constant error, it varies over several spindle rotations, and may not repeat for a while.

That's another secondary effect causing the axis of rotation to move around, at a different rate than due to the races. So there is a *very small* additional wobble that can never be trued-out.

Since none of you have a swiss jig borer, and none of you are MAKING a swiss jig borer (I understand even the swiss don't make them any more), this is "not likely to be an issue"........... (understatement of the year?).

BTW, I understand that much of the concern with this sort of micro-error is not necessarily just about surface finish and precision, but also about ultimate balance and life in extremely high speed spindles, ones spinning at 120,000 rpm or the like. Yet another concern that isn't so likely to be a worry for people here.

Thanks JT.

Another good reality check that should apply to most practicing HSM-ers. I did like the droll "tongue in cheek" bit too!!

It is quite topical that you should mention grinding and higher (medium??) speed spindles as I followed up on a recent series of "Hi-speed Spindle" threads recently and had a good look around for "off-the-shelf" stuff that was not too expensive, would do the job and for which adequate spares and service were available here in OZ. I settled on three items (one I already had) - the other two of which are German-made - "Metabo" and "Proxxon". Suffice to say that they are excellent (I did say that I don't always buy Chinese stuff - just mostly!!). Two are for use as tool-post grinders (internal) and the other as an auxiliary spindle for my mills.

I think that you will be impressed - I hope so.

I will put that post up in the next several weeks - hopefully.

macona
05-30-2009, 08:59 PM
I'll repeat it here ABEC7's will be better then standard bearings - fact but once fitted they start to wear. initially that wear will not be noticable or measurable but at some point it will be equal to a standard bearing.
After that the wear increases until it becomes measurable.

What we don't know is these three points, from ABEC 7 to standard and from Standard to measurable.

.


FWIW, Monarch 10EE's have ABEC-5 spindle bearings. They are custom made matched sets though. I have a NIB set sitting in my filing cabinet.

-Jerry

MickeyD
05-30-2009, 09:23 PM
If you are going to go to the trouble of replacing the spindle bearings - especially with costly ABEC 7 or even 9 bearings, you should really grind the taper after the bearings have run in. This is really the only way to get the spindle bore concentric with the bearings. This will help prevent uneven tool wear and drilling tapered holes. It will also help protect your expensive tooling from all of the scrapes and gouges that some previous owner put in the tapers by using trashed old tooling or heavy handed maintenance.

lazlo
05-30-2009, 09:32 PM
FWIW, Monarch 10EE's have ABEC-5 spindle bearings. They are custom made matched sets though.

They were hand-matched and carefully preloaded, to the point where Monarch guaranteed a runout spec < 40 millionths. In other words, they were hand selecting ABEC-7 accuracy out of a batch of ABEC-5 bearings. The 10EE was designed in the 1930's -- I wouldn't be surprised if ABEC-7 bearings didn't exist yet:

http://www.lathes.co.uk/monarch/page2.html

"With standard spindle run-out of less than 40 millionths, and 30 millionths being an option denoted by a headstock badge, the 113/32" bore headstock spindle runs in super-precision angular contact ABEC5 hand-matched, 60 mm ID bearings with the front being a non-standard and very expensive type fitted with a flange. "

lazlo
05-30-2009, 09:40 PM
If you are going to go to the trouble of replacing the spindle bearings - especially with costly ABEC 7 or even 9 bearings, you should really grind the taper after the bearings have run in. This is really the only way to get the spindle bore concentric with the bearings.

Agree completely Mike -- most machine tool vendors (Bridgeport, as just one example) grind the spindles in their own bearings at the factory, and the good rebuilders like Wells-Index, C&M Spindle, et al regrind the spindle taper after they replace the spindle bearings, as part of their normal rebuilding service:

http://i19.ebayimg.com/05/i/001/14/97/924f_1.JPG

But if you can't afford $75 for a matched pair of ABEC-7 spindle bearings, you probably can't afford $250 to have the spindle taper reground. And if you're replacing precision spindle bearings with common bearings, regrinding the spindle taper is probably a waste.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=120319286094

oldtiffie
05-30-2009, 10:00 PM
If you are going to go to the trouble of replacing the spindle bearings - especially with costly ABEC 7 or even 9 bearings, you should really grind the taper after the bearings have run in. This is really the only way to get the spindle bore concentric with the bearings. This will help prevent uneven tool wear and drilling tapered holes. It will also help protect your expensive tooling from all of the scrapes and gouges that some previous owner put in the tapers by using trashed old tooling or heavy handed maintenance.

You make a lot of sense Mickey.

Ideally the bore/taper should be ground with the whole assembly mounted in the lathe/mill, but of course that is pretty well impractical in many cases. So, the spindle should be ground with the bearing "run-in" and mounted in a simulated head-stock/milling head etc. to simulate the "as to be used in" condition.

Needless to say, in these scenarios, the spindle bearing diameters and thrust/end face will have been "trued up" as well - which implies that any remedial works will or may include regrinding and/or prior "re-building" as if not "to standard" for the ABEC or similar requirements, then non-standard ABEC bearings may be required. What may be light press fit on initial assembly may well turn out to be a light push or transition fit when a new standard ABEC bearing is to be fitted. (We are talking about low-number millionths of an inch here).

In all this talk of super accurate refitting of bearings and re-grindings of bores etc. I seem to never see any mention of equivalent alignment and fitting and re-storation of the housing/case (head-stock, milling/grinding heads etc.) in that it seems to be assumed or presumed that they are "OK" (or just too hard?). Why aren't those faces "touched up" as well? It seems to me to do or be otherwise is considerably less than optimal or a full restoration to "original" standards.

I'd have thought that anything less than a "full job" was close to being not a job at all when we are in these limits.

A bit like being half pregnant perhaps?

And why stop at spindles? Surely to assure "original quality and performance" the beds - and other bits-'n'-pieces would logically need to be looked at?

I have seen some really eye-popping quotes/prices here for restoration of machines either entirely or in part/s.

I wonder just how may HSM-ers have the need or resources (shop, skills, tools and money) to do or have these works under-taken.

J Tiers
05-30-2009, 10:36 PM
Whoa, who said you were a total pratt ?


That was 'prat".... I'm related to some folks named "Pratt":D


Now you are saying its the BB who tell you they don't wear but fatigue.
So what causes them to fatigue ?

look at a bearing you have the ball revolving at one speed, the inner driving it and the outer track is traveled at a different rate because the ball is a constant diameter.

Add to this parts of the ball are in grooves of differing diameters in both the inner and outer so some skidding takes place but this cannot cause wear ?

How can friction be developed between 3 matched speed surfaces ?
It can't there has to be a mis match hence friction, rubbing and wear which CAUSES fatigue.

It's all about LOAD.

If the bearing is not loaded very much, then wear probably IS the failure mode..... mostly wear between the cage and balls.

The fatigue is from the LOAD, because the load causes the balls to deform, and to deform the race. Elastic deformation, they spring back.

But over millions of cycles, that fatigues the surface and tiny bits spall off instead of springing back. When enough has spalled off, it is "end of life" for the bearing.

But according to the bearing companies, primarily New Departure, who nearly invented the ball bearing, and did invent preloaded bearings, the surface fatigue is the primary failure mode for a bearing which is loaded.

They DO mention the variation of speed in the deformed areas, which are oval areas due to the shape of the race, but their point is that the fatigue happens faster than the wear.

So yes, there ARE wear mechanisms, but a clean bearing should fail by becoming noisy and rough before it actually wears measureably. And don't forget, the spalling etc will loosen up the bearing, as well as provide wear-producing particles.

It's something of a chicken and egg deal, but the explanation I have found is that the spalling happens first.

It's not like a journal bearing, which will typically wear to be "egged-out". THAT wear is pretty non-controversial.... you can see it clearly.

Mcgyver
05-30-2009, 11:02 PM
Surface and T&C grinder wheels? As long as they are dressed correctly they will be OK as they are now "true" to the grinder spindle axis. I do balance my surface grinder wheels but I don't have - and don't need - that facility on my T&C grinders.

I'd push back on that one, I've bought cup wheels that definitely needed balancing. a wheel can be out in a lot more places than the cutting periphery. Mind you these were the garbage triumph and camel wheels, not had that with a norton (at 4x's the cost :eek: )


As regards grinder spindles in my shop. If the bearings were "gone" (and I mean really "gone" as I agree with Lane here) I'd replace them with whatever my supplier can get that will do the job

imo, a grinder is a lousy place to scrimp on bearings as the finish will be affected by small fractions of a tenth. Each to there own i guess, but when i spark out on a piece i want it to look good:)


Too many people make far too much an issue of "finish" in surface grinding most times

mechanically, slight finish issues from the grinder might not matter, but a good finish is a perfectly reasonable objective of grinding - i guess it depends on the objective as to how much at matters


you have to make the best of what you have as regards tools, machines, materials - and expectations.

yup.....except on the last one. Like when dealing with a customer, always try to exceed expectations - even if its just to yourself :)


So, don't get "wound up" or unduly concerned about the "high level" talk about spindles and bearings as most machines that are running can and will do a very good job in the average HSM shop.

getting wound up about anything isnt going to any good - but run out absolutely matters - from the view point that saying run out doesn't matter is meaningless unless you define 'how much' does or doesn't matter. At some TIR number, it would matter to even the most 'good enough' rough 'n ready chip making metal destructor. i would think its a fairly small number that starts to make a material difference in a mill as cutters start to cut on one tooth as run out increases....BUT if I measured the run out tomorrow and was surprised at a high number i don't think id rush out and buy bearings as the mill is performing just fine


Most people here and their machines can do very good work. Don't be intimidated by others. Just use what suits you.

I've done good work on crap machines. My equipment is better today than its been in the past and will be better still in the future, point being a machine that is a little rough doesn't preclude nice work but that isn't the same as saying what evers rough about it doesn't matter....we can compensate but longer term we improve our equipment because its much nicer not having to.

oldtiffie
05-30-2009, 11:21 PM
I agree with you McGyver.

But having said that, there is nothing wrong with a HSM-er - what-ever his skill level - buying a machine he can both afford now and can afford to up-grade or replace later as his skills, resources and needs change.

Lets not stop at the bare machines either as all too often the associated tools and accessories can cost as much as the machine/s and all too often they determing just how good a job a machine or HSM-er can make/do.

Its surprising how little mention is made of ensuring that all cutters - especially milling and TC - are not only sharp but kept sharp.

We can and should aspire to better work and better tools as well as better satisfaction and recognition by our peers etc. as we all like a pat on the back and the satisfaction of a lesson learned and a job well done.

We all have aspirations but we all have limits of one sort or another as well.

Wanting the "best there is" is not always the same as needing it.

As long as we are happy in our shop doing well in what we do we are a successful HSM-er.

oldtiffie
05-31-2009, 05:34 AM
Originally Posted by oldtiffie
Surface and T&C grinder wheels? As long as they are dressed correctly they will be OK as they are now "true" to the grinder spindle axis. I do balance my surface grinder wheels but I don't have - and don't need - that facility on my T&C grinders.


Originally Posted by mcgyver
I'd push back on that one, I've bought cup wheels that definitely needed balancing. a wheel can be out in a lot more places than the cutting periphery. Mind you these were the garbage triumph and camel wheels, not had that with a norton (at 4x's the cost)

Sorry mcgyver.

I either forgot or missed that part of your post.

I'd agree with that 100%.

I only use (and can probably only get) genuine Norton (owned by a French Company called St. Cobain) wheels which are really good as regards balance, right out of the box. There is very little "side-wobble" either in those "Norton" new wheels - disk, cup, saucer etc. wheel on my T&C grinders - which don't have a balancing hub - there is little or no discernible vibration at the grinding head. I dress the disks (7") with a diamond but the rest are dressed with a handheld dressing stick.

I do balance the wheels (usually disk) on my surface grinder which has a balancing hub. I balance and dress and re-balance and redress my wheels in an iterative/reducing process until I get it right.

Its fair to say that the finish on the surface grinder is usually better than on the T&C grinders in surface grind mode.

I usually use the coarsest wheel that I can for both stock removal and finish. If I need a finer finish I will use a finer wheel.

In theory - but not in practice here - I suppose, that to get optimum parallelism on my jobs that I should take a light cut over my magnetic chucks, but as they usually have a maximum TIR of about 0.0001>0.0003", I don't bother unless I need to.

I am in pretty good hands as regards damage to wheel bearings due to wheel imbalance.

lazlo
05-31-2009, 05:46 AM
I only use (and can probably only get) genuine Norton (owned by a French Company called St. Cobain) wheels which are really good as regards balance, right out of the box.

Norton has two lines of wheels -- the entry-level Norton "Gemini" grinding wheels are made in China, and the few that I've run across had crappy balance.
I've found the "real" Norton do have excellent balance out of the box.


I do balance the wheels (usually disk) on my surface grinder which has a balancing hub. I balance and dress and re-balance and redress my wheels in an iterative/reducing process until I get it right.

The Norton grinding manual says that there's no point to balancing good quality wheels smaller than 10".

oldtiffie
05-31-2009, 06:25 AM
Thanks lazlo.

I agree with all of that.

I only use, and from my supplier, can only get, the Tool Room/Production wheels as he (not Hare and Forbes) only supplies to the "Trade" as his reputation depends on it too. Plus he has the full "Norton" catalogues and price lists.

As said, as a matter of course, I check the balance and dress my surface grinder wheels every time before I load them. I have four balanced hubs and leave three of them permanently mounted with three different wheels. I have to say that any balancing adjustment and dressing are absolutely minimal which also confirms what you say.

I had an eye-opener when I bought a lot of small wheels for my new heavy-duty "Metabo" (German) die-grinder that I am going to use as a tool-post grinder for my universal grinder (more later). I had to place minimum orders of 10 per wheel. Not too expensive at all at bulk and "Trade" prices.

They came with a series of charts of maximum spindle speeds per shaft/spindle size/"stick-out" and wheel type and size. There were some surprises there. Most of the wheels were made in Mexico.

I will post those charts in the next day or so as they should be of use to anyone who just "wings" those spindle speeds.

oldtiffie
05-31-2009, 07:53 AM
Lazlo.

The "charts" for the smaller wheels (Tool-post grinders and Die grinders) mentioned in my previous post are here. The print is pretty poor as it was originally, but it was very small in the originals and the scanning was an inevitable compromise. The wheels are much better than the chart quality but the chart content is OK.

http://i200.photobucket.com/albums/aa294/oldtiffie/Med_Speed_Spindles/Mounted_wheelscover1.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Med_Speed_Spindles/Mounted_wheelsfront-piece1.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Med_Speed_Spindles/Mounted_wheelspage1.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Med_Speed_Spindles/Mounted_wheelspage2.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Med_Speed_Spindles/Mounted_wheelspage3.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Med_Speed_Spindles/Mounted_wheelspage4.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Med_Speed_Spindles/Mounted_wheelspage5.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Med_Speed_Spindles/Mounted_wheelspage6.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Med_Speed_Spindles/Mounted_wheelspage7.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Med_Speed_Spindles/Mounted_wheelspage8.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Med_Speed_Spindles/Mounted_wheelspage9.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Med_Speed_Spindles/Mounted_wheelspage10.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Med_Speed_Spindles/Mounted_wheelspage11.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Med_Speed_Spindles/Mounted_wheelspage12.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Med_Speed_Spindles/Mounted_wheelspage13.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Med_Speed_Spindles/Mounted_wheelspage14.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Med_Speed_Spindles/Mounted_wheelspage14.jpg

Mcgyver
05-31-2009, 11:05 AM
As long as we are happy in our shop doing well in what we do we are a successful HSM-er.

end of the day, that's all the matters. What we 'need' almost doesn't make sense in a home shop context......I don't need any of it. I don't need a lathe, a mill or a grinder. I don't need spindle bearings. I don't need to work to tenths, thous or hundreds. I don't need to make tooling, engines or machine parts. Its all what Manslow would call self actualization



The Norton grinding manual says that there's no point to balancing good quality wheels smaller than 10".

Agreed - important that you note that its when good quality wheels are used. We should all buy $100 wheels, but when we don't, it's worth checking both for finish and for being kind to the machine. The other thing to remember when the pros tell you us you don't have to balance is they are generally using heavier equipment - I profer that the importance of balance changes with the rigidity of the machine and the pro's are biased in that sense.