Set and forget mill vise squaring?

Pat Matthews

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As a young'un, a shop owner showed me a technique for machining slightly offset t-slot keys to precisely match a vise to a mill. Now I'm 60, and can't recall how it went.

Maybe it was something like:
1. Install close-fitting keys (may be stepped keys to match vise and T-slot);
2. Shove vise against one side of T-slot;
3. Measure jaw mis-alignment;
4. Mill that much off one key (on its T-slot face);
5. Then always load the vise against that side of the slot to get dead-nutz alignment.

But this doesn't sound exactly right, I thought he ended up with a snug-fitting key and a vise that never needed preloading or dialing in.

Also not sure if it would be worth it, might be best to dial in each time anyway.

Thoughts?
 

Bob Korves

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Your ideas are good. Anything that saves time and gives a solid and repeatable setup is a good idea.

Welcome to Hobby Machinist!
 

David S

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First welcome to the forum Pat. My set up is smaller than normal milling vise set ups but I got tired of traming in the vise all the time so I added a couple features to the bottom of the vise. The left post is fixed, and the right one is mount with an eccentric hole so that it can be adjusted allowing me to set the vise in the T slot and push it back against the stops while tightening it down.

vise alignment pins.jpg

David
 

RJSakowski

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My vise has two sets of slots milled in the bottom that are parallel and perpendicular to the jaws. A pair of keys which fit the slots came with the vise. When the keys are installed and the vise is mounted with the keys in a T slot on the mill table, the jaws of the vise are, in theory, parallel to the ways. Specifically, my Tormach 770 has the front edge of the middle T slot ground parallel to the ways for just this purpose.

If your vise doesn't have such a provision, here is what I would do.
1. Sweep one edge of the T slot with a test indicator to verify that it is straight and parallel to the ways.
2. If not straight and parallel, make a skim cut with and end mill to true the edge.
3. Mount piece of ground flat stock in the vise so that the stock has about 1/2-3/4" above the jaws.
4. Place the vise upside down on the table with the flat stock with the near side of the ground stock tight to the good T slot and clam; in place.
5. Mill a slot in the bottom of the vise. If there are holes in the vise base for fastening it to the table, the slot should be located so the front edge is forward from the centerline through the holes by half the width of the T slot. The slot can be fairly shallow and should be narrower than the T slot. make two keys to fit the slot, drill and counterbore for a socket head cap screw. Locate the keys in the slot, slightly inboard of the mounting holes, if any, to eliminate the possibility of interference with the T nuts. Drill and tap holes for mounting screws
6. Place the vise right side up on the table and mount it, making sure that the keys are tight to the front edge of the T slot. Make sure that the vise didn't "walk" during tightening.
7. Sweep the fixed jaw of the vise to verify that it is parallel to the ways.

When I mount my vise, I use a block of wood between the vise and the column to ensure that the keys are tight to the front of the T slot. I tighten my mounting bolts and remove the wood block and I am ready to go.
 

Bob Korves

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Round and smooth the bottom corners and edges of the keys carefully so they will not scratch the table when installing and removing the vise.

Edit: Round and smooth the exposed vertical corners as well. Then they will not dig in to the t-slots.
 
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Karl_T

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I've keyed the bottom of my vise as outlined above. At least on my mill, one end will be three or four thous ahead of the other just clamping the vise down. Some with height, the bottom of the vise will be a few thous higher on one side than the other. Good enough for most, but not all, jobs.

When you need it spot on, I think soft jaws are the way to go. If fact i hardly ever have hard steel jaws installed. Just shave a few thous off the jaw to have it spot on in all axis.
 

higgite

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When you need it spot on, I think soft jaws are the way to go. If fact i hardly ever have hard steel jaws installed. Just shave a few thous off the jaw to have it spot on in all axis.
Karl,

That's pretty sneaky. I like it. What material do you use for the soft jaws? After you have shaved them into plumbness (that has to be a word), do you remove them to chamfer the mounting holes to be sure that there are no burrs to interfere with their "flatness"? Or is that overkill?

Tom
 

Bob Korves

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My keys fit the chuck and table snugly, and I milled the mild steel jaws in place after mounting the chuck. It is always within .001", and within .0005" (over 6") with a bump in the correct direction. I have stopped tramming the vise completely, no reason to do so.
 

Karl_T

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Re:Soft jaws.

Bob is doing his soft jaws out of mild steel in the post above. I prefer AL and make the jaws about two inches wider than the vice, a half inch higher than the vice top. Also, a bit thicker than the original jaws. I buy AL stock twenty feet at a time and make up bunches of them.

For my needs, I always start by making a notch about 0.200" wide by 0.200" deep. Nearly all parts are then held here with no need for parallels. I also have no problem with making a pocket to hold irregular parts.

FWIW, this is pretty standard industry practice.
 

Bob Korves

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I've keyed the bottom of my vise as outlined above. At least on my mill, one end will be three or four thous ahead of the other just clamping the vise down. Some with height, the bottom of the vise will be a few thous higher on one side than the other. Good enough for most, but not all, jobs.

When you need it spot on, I think soft jaws are the way to go. If fact i hardly ever have hard steel jaws installed. Just shave a few thous off the jaw to have it spot on in all axis.
You can make one new key to make up for the inaccuracy in the table or the vise. Or machine the jaws in place, like you did.

Bob is doing his soft jaws out of mild steel in the post above. I prefer AL and make the jaws about two inches wider than the vice, a half inch higher than the vice top.
And I prefer the mild steel jaws. They grip better than hard jaws, deform much less than aluminum jaws, and can be skimmed true as needed. They are also quickly and easily and cheaply replaced from the bar stock I have on hand. Yes, I do understand that in industry, aluminum soft jaws are commonly used. The mild steel ones seem to work better for me in my hobby shop.
 

RandyWilson

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And here I thought I had committed the greatest of sins when I cut the jaws square. Thanks for all the ideas on how to make this antique Palgren more usable.
 

rjitreeman

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In theory, clamping an overheight piece of bar stock (a parallel)in the vise. Flip vice and force to rear of slot while clamping. Tram the bar or stationary jaw. Should be dead on assuming T slot is parallel to ways. If it is other than dead on, leave indicator on jaw a bar and push/ pull the bed in y axis. If it moves at all, give may be looser than necessary. If it is off, then one of the other solutions may be the answer.
Thoughts or comments?
 

Djl338

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Where do sine keys on Kurt vises fit in? about $30/per from Kurt, so they must do something special I can’t figure what the advantage is unless you have a grid table to fit it in.
 

Firstgear

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Where do sine keys on Kurt vises fit in? about $30/per from Kurt, so they must do something special I can’t figure what the advantage is unless you have a grid table to fit it in.
I have a Kurt 6” and bought the keys direct from Kurt. They were $48 for a pair. The price has recently been lowered.

You can see from the application drawing where the diameter fits on the bottom of the vise. The square portion of the sine vise fits in the slots on the mill bed.
 

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Djl338

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When I looked at them yesterday they were $$55/pair plus a 4% tariff which I thought was for Chinese imports, thought Kurt was totally USA, so close to &60/pair, fair enough if they do something unique and special. I get where they go but was wondering about the advantage.
Sine keys
 

Firstgear

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Gets you close quickly to tram....that is what it does.
 

tq60

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On bottom of vise mill a slot same width as T slots through center of mounting holes, making sure square.

Make special t nuts tall enough to fit the slots but still have headroom.

Fast and easy, still training only takes a minute or so with correct DI in a coller or chuck.

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Djl338

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This is what I was looking for, found it in an old post;
"The reason for the round "sine keys" instead of square keys is so the vise can be mounted at odd angles"
 
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