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biometrics
10-15-2008, 10:11 PM
First of all, I would appreciate it if the experienced machinist folks on this board would critique the procedure I am about to describe and provide the pro’s and con’s of using it.

Some many months ago, before I got actively back into the metalworking hobby, I read an article on the web, probably on a personal website, that described and demonstrated how to achieve proper alignment of a milling vise on the milling machine table so that the vise jaws were accurately aligned with the movement of the table by the use of a key installed on its base.

In a nutshell… a plate is created with a thickness is exactly the width of the t-slots in the mill table. The plate should be at least as wide as the vise jaws, and protrude above the vise jaws by a distance that is just short of the depth of the t-slots.

This plate is then clamped tightly in the hard vise jaws, and the vise is then turned upside down and centered on the table with the plate inserted into the t-slot that is closest to the middle of the table. Using machinist jacks and clamps, the underside of the vise is then leveled and the vise is clamped to the table for modification.

Now the table is adjusted so that the best part of the milling vise base can have a slot milled across its width at a reasonable depth that does not jeopardize the integrity of the vise base. This procedure aligns the new slot with the vise jaws.

Finally a key is manufactured from the original plate that will serve as a key that is drilled and installed into the vise base. Once this key is installed, when the vise is placed on the mill table, it is as close to being aligned to the t-slots in your table as your hands can place it before you bolt it down.

If the key is inappropriate for your milling job because you don’t want the vise jaws in alignment to the t-slots, it is easily removed by unbolting it… and just as easily replaced when you go back to your “standard” setup.

The original web article I read also included some great photos of the procedure that I think would be helpful to new machinist hobbyists and professionals alike.

Now for my 2nd request…I have lost my link to that original website, and if anyone knows the website where that article appears, I would appreciate it if you would post the link here so that others can benefit from it, and so the original author can receive appropriate credit for the idea.

I intend to post this request over on the PM board also so that those who do not frequent this board may be able to respond to my request.

Thanks in advance.

-John

wierdscience
10-15-2008, 10:32 PM
Easier method is to clean the tee-slots edges off with a file file to remove any dings.Use the tee slot and some bolts to clamp a section of 1-1/2" or so sqaure bar to the table.Mill the front and back face of the bar true to the table travel.Invert vice and clamp onto the bar.Make two new vice keys to fit the vise slots tight and install on vise.Measure the width of the tee slot and mill the keys inplace on the vice to +.0003-.0005" wider than the table slot.

SilveradoHauler
10-15-2008, 10:32 PM
T-slots are not necessarily aligned to the ways of the milling table

Think I will set up an indicator and check out the T-slot alignment on my 60 inch table. Might be fun to see where they are.


I would still indicate in the back (stationary) jaw of the vise. I have keys on my vises, but they are a few thou loose in the T-slots, allowing me to have some wiggle room for dialing in the back jaw.

JoeFin
10-15-2008, 10:39 PM
John

Maybe I’ll get flamed for this – but I simply indicate the position of the vise in relation to the spindle. “Tap – tighten tap tighten” until the vise is fully secured square and plumb.

Now as for the vise, (and fellow home machinist keep talking me out of some of my best work) are square and plumb because if they aren’t I fix them. Yes I have a Kurt, and also a Bridgeport that is equally square and plumb after being reworked. But they got my 1920s Columbian, and my Brown & Sharp #3 with swivel base, after they had been completely reworked.

I take the time to completely disassemble them, weld up with nickel rod any drill/mill marks, clean and file them meticulously, make new jaws if necessary, and then precision grind the jaws, body, and base to .0001 parallel and square.

So when I square the jaw to the spindle, the top and side is also square and plumb to the table and spindle

wierdscience
10-15-2008, 10:48 PM
T-slots are not necessarily aligned to the ways of the milling table

Think I will set up an indicator and check out the T-slot alignment on my 60 inch table. Might be fun to see where they are.


I would still indicate in the back (stationary) jaw of the vise. I have keys on my vises, but they are a few thou loose in the T-slots, allowing me to have some wiggle room for dialing in the back jaw.

That can be fixed quickly with a sharp endmill.Some use clamps and indicators,some like me don't,I don't have the time,those key slots aren't milled in the bottoms of vises because the're pretty.;)

Tim Clarke
10-15-2008, 11:05 PM
I have a nice 6" vise. No keys when I got it. Starting from scratch, it would take a while to tram it in. Like many guys, I wanted to have some keys to make life easier. So, I made a set to fit in the base of the vise. I decided that I wanted it to be close anywhere along the table, not just one place. Also in any of the 3 t-slots. So, I made the keys about .005 smaller than the t-slots. I put the vise on the table, and push it to the rear, then tighten the bolts. it's close anywhere I bolt it down, say, .003 or so. Anywhere I want it close, I tram it in. Pretty easy if it's already within .003. Easy to make the keys, good to go for some jobs, easy to get close for the rest of my work.

Try it, you'll like it

TC

joeby
10-15-2008, 11:12 PM
I don't have any keys in any of my vises/fixtures. I don't trust the t-slots to be inline with the ways on any machine, and since I use the same vise on more than one machine it would cause some grief because one has metric slots.

I just got used to snugging up the right hand bolt and zeroing an indicator on the right side of the fixed jaw, then move to the left side and bump the vise to the same reading. a couple of passes like this and you're done. One of the bigger shops I worked in had 80+ toolmakers working there. You were required to remove everything from the machine table when you were done and return the vise/rotary table/dividing head/whatever to the racks in the back of the shop. All the keys had been removed from the tooling because of the number of machines it could be used on and the fact that you never relied on someone elses workmanship.

That said, if you were sure of the slots being straight and true with the ways, and the vise was to be used on that particular machine only, it would save a minute or two.

I actually had a guy tell me that Bridgeport milled their t-slots in after the machines were assembled so they were dead straight. I would like to see this done since the slots are longer that the table travel.

Just my $.02, whatever that's actually worth today.

Kevin

small.planes
10-16-2008, 03:31 AM
I have no keys in my vice. I use a technique with a long piece of straight bar. Clamp bar in vice, plonk on table and snug up. then sight the bar and the T slots parrallel. Can get my vice plonked on to about 1 thou in 6" (good enough for most work) in a few seconds. Printers are a good source of PG bar, the print carriage runs on them.

The bridgeport can mill its own t slots because the table doesnt have to move under the head for all of the travel, you can move the head as well, so if you extend the ram and twist it sideways you can mill a much bigger area. Same for all turret mills.

Dave

John Stevenson
10-16-2008, 04:01 AM
Get a 'U' shaped piece of steel that longer than the vise jaws in the cut out portion and higher than the jaws on the legs.
Thickness needs to be just less than the narrowest slot on your machines.

Make sure at least one side is flat.
Then take that piece and clamp it in the vise, good side to the fixed jaw and with the legs protruding into the tee slot.

Push forward until it touches, then clamp vise.

If done right it will be bang on and will fit different vises and machines.

If your tee slots aren't parallel to the travel then sort it don't moan about it.

.

joeby
10-16-2008, 06:41 AM
It all comes down to personal preference and whether you think it will save you time. I prefer to indicate because that is how I've always done it, and I know it's right because I just checked it.

Small planes, yes, you are correct; but my point was that I don't think Bridgeport would take the time to do that in a production environment? I don't doubt that they are very close (I never took the time to check all of the Bridgeports I've used); but I seriously doubt they mill the slots after assembly.

John, I don't recall any moaning.

Kevin

oldtiffie
10-16-2008, 08:34 AM
First of all, I can't see that too many HSM's are in such a hurry that they can't spare a couple of extra minutes to get it done from scratch. If yoiu are tear-arsing like that you are putting yourself at a higher level of risk than you may either need to or realise.

I take all my keys (that fit in the slots at the bottom of my rotary tables, vices etc. to mate with the slots on my mills grinders etc) off - and leave them off. They are a total PITA as they foul everything, scratch as they slide, and won't let the vice, table etc. sit flat on the shelf for storage. Just about every one if different.

There is no guarantee that all tee-slots are vertical or the same width as each other and from end to end of the table nor parallel to the "X" axis dove-tail slide axis. So on that basis I assume that they are not as I would like them to be and work accordingly.

If I must use those bloody slots under the vice etc., I use a couple of say 1" x 1/4" cold-rolled flat bar that is just long enough to sit on the bottom of my tee-slots and project about 1/8" above it. I drill and tap a 1/4" thread in them so that it is at about the height of the centre of the "over-hang" at the top of the tee-slot. I put a matching short screw into it and screw the head out until it engages the opposite side of the tee-slot and then tighten it. It is now tight in the tee-slot and the outer face is dead in line with one face of the tee-slot. I just drop the vise etc. with the slot under it over the projection, pull/push it to "hard up" and clamp the vice or rotab etc.

Dead easy and one pair suits any/all stuff with alignment slots under them - and no unnecessary machining required. If I lose one or more I can make new ones with a hack-saw, a file and a drill and tap and a screw to suit.

I really do get pi$$ed off with all these unnecessarily difficult and time consuming "gospel" texts from hallowed texts of "traditional" methods by authors who must have been canonised to Sainthood. A lot of their stuff makes sense, but a lot doesn't, and they tell you what to do without explaining why that way is the best or only way. It may well be so - and it may well not.

The objective after all was only to align one side of the tool slot with one side of the tee-slot after all - no more and no less.

I don't like prescriptive methods - I do like performance-based/oriented ones though!!!

Anyway.

I usually just put the vice etc. on the table, "eye" the fixed jaw in to the tee slot, lightly clamp the (left or right) clamping bolt, and pivot the vice around it as I progressively/reiteratively "zero" the dial indicator and thus align the fixed jaw to the "X" axis by using a dial indicator on the fixed jaw and my rapid traverse on my "X" drive. When it is zero, I fasten the "loose" clamp bolt and re-test the alignment. If all is OK, I tighten both clamp bolts, re-check for zero and if OK I am set to go.

With this method I am assured that the vise fixed jaw is aligned to the "X" axis and all or any problems with errors in the tee-slots and slots under the vice etc. are eliminated.

I've been doing these things this way for a while and I get results that satisfy me.

I will not seek to impose my method upon anyone else. It is up to them to make their own independent judgment as to what suits or "works" for them.

3jaw
10-16-2008, 09:17 AM
I just got used to snugging up the right hand bolt and zeroing an indicator on the right side of the fixed jaw, then move to the left side and bump the vise to the same reading. a couple of passes like this and you're done.

I agree joeby. This is the way I do it and the way I teach my students. Indicating is the only 100% foolproof way of ensuring that your vice is parallel to the table travel. The snugged bolt is used as a pivot point. Quick and easy.

derekm
10-16-2008, 09:27 AM
I'm with John Stevenson as the simplest method to quick align a vice and had thought of the same idea.

However how do a quick simple align like this for a rotary table and a divding head ?- because I'm with Tiffie on not wanting stick out keys on the kit for the same reasons.

JCHannum
10-16-2008, 09:38 AM
I use a key on my main milling vise, installed as described. I did check the ways for accuracy and shimmed the fixed jaw true after mounting. Life is too short when changing setups to be continually bumping the vise in when a very short time spent in installing the key eliminates the need for it.

There is little to be gained in keying a RT as the spindle needs to be dialed into the table center. There have been several posts on aids to centering the RT.

oldtiffie
10-16-2008, 09:53 AM
...................................

However how do a quick simple align like this for a rotary table and a divding head ?- because I'm with Tiffie on not wanting stick out keys on the kit for the same reasons.

Derek.

Just sit your rotab on the mill table, with the clamp bolts loosely tightened. Use a good try-square on the front or back face of the mill table and tap/"bump" the rotab until the machined/ground vertical face lines up withe the square blade. It works when the rotab is vertical or horizontal. It might surprise you how accurate you can get this way. As a check, use a dial indicator and the "Y" slide to check.

And again - no keys needed.

If you want to set it at angle other than 90, use a good protractor.

No keys needed here either.

I prefer to have my rotab "lined up" as it is surprising how often I use the degree scale on the rotab. It works for "near enough" stuff. Otherwise I use the worm hand-wheel calibrations.

derekm
10-16-2008, 09:55 AM
...

There is little to be gained in keying a RT as the spindle needs to be dialed into the table center. There have been several posts on aids to centering the RT.
hmm I would beg to differ on a dividing head or a vertical RT. And also if you have to remove a set up horizontal RT and then replace it later and maintain the relative angle to the X axis.

Must be of use to some one on Horiz. RT because my Fritz werner has them as standard on both the bottom and on its own table

derekm
10-16-2008, 10:00 AM
does anyone use/make keys that you clamp to the table rather than the kit?
and how on earth do you mill a key slot on the bottom of a dividing head?

oldtiffie
10-16-2008, 10:12 AM
Derek.

Use the front or rear ground faces of the dividing head as they are parallel to the spindle axis.

Use these simple "edge of tee-slot locators" and just pull/push the ground faces of the dividing head up to them. If the clamping holes in your DH don't line up, just put the "locators" in another mill table tee-slot, make a simple parallel spacer to suit and use it.

Dead simple.

If in doubt and/or as a check, use your dial indication on the DH ground faces and align to the "X" axis.



If I must use those bloody slots under the vice etc., I use a couple of say 1" x 1/4" cold-rolled flat bar that is just long enough to sit on the bottom of my tee-slots and project about 1/8" above it. I drill and tap a 1/4" thread in them so that it is at about the height of the centre of the "over-hang" at the top of the tee-slot. I put a matching short screw into it and screw the head out until it engages the opposite side of the tee-slot and then tighten it. It is now tight in the tee-slot and the outer face is dead in line with one face of the tee-slot. I just drop the vise etc. with the slot under it over the projection, pull/push it to "hard up" and clamp the vice or rotab etc.

Dead easy and one pair suits any/all stuff with alignment slots under them - and no unnecessary machining required. If I lose one or more I can make new ones with a hack-saw, a file and a drill and tap and a screw to suit.

Circlip
10-16-2008, 11:52 AM
To answer your original question Biometrics, the article was shown on Home Model Engine Machinist by John Bogstandard. Have used both methods, Keys and plate clamped in vice jaws, depends how quick you want to be, both can be accurate. Used keyways on base mounting plate of a rotary table and a vice mounting jig on lathe cross slide slots. This is a lathe that has an attatched milling head.
Regards Ian.

dockrat
10-16-2008, 01:40 PM
Get a 'U' shaped piece of steel that longer than the vise jaws in the cut out portion and higher than the jaws on the legs.
Thickness needs to be just less than the narrowest slot on your machines.

Make sure at least one side is flat.
Then take that piece and clamp it in the vise, good side to the fixed jaw and with the legs protruding into the tee slot.

Push forward until it touches, then clamp vise.

If done right it will be bang on and will fit different vises and machines.

If your tee slots aren't parallel to the travel then sort it don't moan about it.

.

Now THAT one I like. Thanks John....gunna use it. If nothing else there shouldn't be a lot of indicating :)

small.planes
10-16-2008, 01:47 PM
Small planes, yes, you are correct; but my point was that I don't think Bridgeport would take the time to do that in a production environment? I don't doubt that they are very close (I never took the time to check all of the Bridgeports I've used); but I seriously doubt they mill the slots after assembly.

Kevin,
Ive never worked for bridgeport so cant say for sure ;) , but those slots have to be milled somehow, and a T shape cant be done on a horizontal. given the machine probably needs testing under power I dont see it as that far fetched, and I was sure Id seen an ilustration of it being done somewhere on the internet...

Dave

dp
10-16-2008, 01:51 PM
Now for my 2nd request…I have lost my link to that original website, and if anyone knows the website where that article appears, I would appreciate it if you would post the link here so that others can benefit from it, and so the original author can receive appropriate credit for the idea.

-John

http://www.frets.com/HomeShopTech/Projects/PalmgrenMods/palmgrenmods.html

derekm
10-16-2008, 01:54 PM
Kevin,
Ive never worked for bridgeport so cant say for sure ;) , but those slots have to be milled somehow, and a T shape cant be done on a horizontal. ...
Dave

Oh yes it can.

just needs an angle plate.

small.planes
10-16-2008, 02:04 PM
OK, didnt think of that, was only thinking of the table in its horizontal position :o

Dave

lane
10-16-2008, 07:36 PM
Oh yes it can.

just needs an angle plate.

Why does it need a angle plate . Lay back face down on mill table and clamp down Indicate face mill slots . No angle plate needed.

Rich Carlstedt
10-17-2008, 12:34 AM
There is some misunderstanding here.
First, let me say that current Asian Machine tools may, or may not, follow
the Practice of American and European Machine builders, when it comes to milling tables. I haven't checked any recent machines of this manufacture, so am not qualified to comment.
The practice has been that "T" slots are made perfectly parallel to the ways.
One " out side" surface is also parallel "IF" Possible, but not held to the exact same measure. The other side surface is not parallel as a criteria.
Measurements were made in the 1980's when we qualified machines for production and are shown in the following example for your understanding

A new Bridgeport had the keyways dead on parallel to the REAR side surface of the mill, while the front surface varied by .0035. ( this means if you used a square in the front, your vice would be cocked !).
Brand new 5 axis Italian Boring Mill (400,000 $ ) was checked and the table and keyways were deadnuts to the front surface, but .008 out on the rear. This was a 78 " long ( 2 M) table.
Brand new Alliant mill ( BP style) had less than .0008 error from
rear of table to keyways, and like the BP, the front varied.

The reason for keeping keyways parallel to THE WAYS, is simple.
Vices (W/Keys) can be moved left or right, and not change in relative position on the Y-axis . This is paramount for accurate reproduction of work.
Next, angle plates are mounted with "keyway stops”, again parallelism is paramount for accurate work. In industry like Die making, you don't waste time
having fixtures that create error potential or failure, because the piece parts cost too much. So Machinery Makers Know this.

Many old mills have banged up keyways, and that is unfortunate ! bigtime !

If you don't know your mill, I suggest you check it out by placing an indicator on the sides of the keyways, and then check the front and rear surfaces.
A good method is to divide the table into 4 sections( 25%, 50 %, 75 %) with a magic marker.
With the table centered, place the indicator at the 25 % position and move L and R and record the movement . You will cover from 0% to 50 % in travel.
do the same at 75 % and get 50 to 100. Compare the 50 % readings and account for any changes. You may find it is perfect, or tapered, or bowed !.

Why is the rear surface Parallel you may ask ?
Well, when the table is ready to have the ways ground, the builder has two choices to set it on the grinding table. He can set it on the front, which has the stop slots milled in ( Burrs Guys !), or the rear, which is plain and flat.
So they set it on the rear, and the front dovetail is ground. OK ?
Now, they flip the table over...BUT you never grind the second ways using the sides ! You use dowels to support the table, by using the previously ground front ways to get a "perfect" parallel way. The same holds true for the T slots, when milled, they may use the front ways if done, OR the first surface that will be used for grinding the ways

So what is the proper way to machine keys on a vise ?
Make them oversize and install.
Put a plate in the milling table keyway that is snug as possible
Flip the vise over and clamp it on the plate using the vise itself.
Clamp the vise to the table with other clamps.
BE SURE TO PLACE THE HANDLE END AWAY FROM YOU, towards the column. If you have the handle near you instead, and the table keyway is off, you will have double the error !
Now mill the width of the keys to snugly fit the keyway.
This important point is usually missed by those who make keys, and results in them “next” being made smaller because those damxxd don’t work !

Should you use keys ?
I thnk so, you lower stress on the milling table, because you don’t need to
Super torque the hold down T studs, which causes the table to deform.
You don’t have to worry about the vise moving and loosing a critical dimension.
Last, its fast and you can change in and out and never loose position.

Just my thoughts
Rich

websterz
10-17-2008, 01:02 AM
I have a pair of blocks ground to fit into the T-slots on my mill. I drop them into the back slots about 12" inches apart and set the vise on the table between them. I then take a piece of surface ground 1" square keystock about 14" long and clamp it into the vise, slide it back until it is snug against the blocks and clamp the vise down. Close enough for 90% of what I do on the mill.

Paul Alciatore
10-17-2008, 02:33 AM
An alternative to the slot and key thing is to construct a "square" that fits into one of the slots and has a upper rail that the side of the vise can be laid against. A third diagonal member completes the assembly and with a bit of clearance in the screws allows it to be adjusted for 90 degrees. This "square" can be used with multiple vises if they all have at least one flat side. It is removed after the vise is aligned and at least one clamp is tightened. I have several different vises for different purposes and the ones that did not have a flat side I simpily milled one. This flat does not have to be removed like a key would when the vise is used on a different angle.

After mounting a vise for the first time with this technique, I use a long milling cutter to take a light cut on the fixed vise jaw to true it up. This cut makes the jaw dead true to the movenent of the mill table and can fix other problems with a less expensive vise. And it makes up for any errors between the jaw and the flat on the side. You may not want to do this on an expensive one.