Get Material Flat in Vise

[mcman56]

I have an old mill vise and frequently struggle to get material to sit flat. I use parallels, tighten and then tap on material so that parallels will not slide. Sometimes or frequently, I can not get this to work and the parallel on the movable side of the vise continues to slide. The attached picture shows the result when I rotated material 5 degrees in the vice and took a cut. You can see the material is higher on the movable side of the vise. (It was originally cut holding the long sides but I needed to switch to holding the short sides for this 5 degree operation..)

I don't know the brand of the vise but it does not have a dovetail. It just has flat plates that bolt on the bottom to hold the movable side down. I have tried tightening these until there is a lot of drag but still have the problem. Is there anyway to improve this situation. My next project will require things to be quite flat.

[earlgo]

Hah. I had one of those vises that did the same thing, but not the same brand. It just did the same thing.
You could insert a section of round rod horizontally between your part and the moveable jaw to help alleviate the up and down movement. You would still have to tap the top to seat the part on the parallels.
Failing that, check whatever sources you have for a KURT vise. Problem solved, but they are expensive.
--earlgo

[Conrad_R_Hoffman]

I had a cheap Kurt copy for some years. Worked OK, but still had the same lift problem. Eventually sold it at a flea market for cheap and bought a Kurt. It's hard to appreciate how much difference the vise can make in your work quality. Depending on what you make, one solution might be to buy a grinding vise, clamp the parts, then put the grinding vise in the big vise. If it goes well below the plane of the screw, the jaw isn't likely to lift.

[mcman56]

I was not planning on a new vise. How did machinists deal with this in the "good old" days. Kurt vises look quite pricey. Are there some decent clones?

[Harold_V]

I was not planning on a new vise.

I strongly suggest you review that decision.

How did machinists deal with this in the "good old" days. Kurt vises look quite pricey.

By using large soft hammers (typically cast of lead). Even then, the problem wasn't solved. They lived with the conditions that could be generated.

Are there some decent clones?

Some are reputed to be as good. I can't say, as I use only Kurt.

Plain and simple. If you hope to do better work and not fight the known fight, get a Kurt. You won't believe the difference it makes.

I do NOT have stock, or any monetary interest in Kurt. I own two of them. I wouldn't have it any other way.

H

[Mr Ron]

I was not planning on a new vise.

I strongly suggest you review that decision.

How did machinists deal with this in the "good old" days. Kurt vises look quite pricey.

By using large soft hammers (typically cast of lead). Even then, the problem wasn't solved. They lived with the conditions that could be generated.

Are there some decent clones?

Some are reputed to be as good. I can't say, as I use only Kurt.

Plain and simple. If you hope to do better work and not fight the known fight, get a Kurt. You won't believe the difference it makes.

I do NOT have stock, or any monetary interest in Kurt. I own two of them. I wouldn't have it any other way.

H

If I got a used Kurt vise, would it still be as accurate as a new Kurt ?

[GlennW]

Even with a Kurt you need to tap the workpiece down against the parallels, but it is minimal.

I use a 10 oz Deadblow plastic hammer and just give it a light tap. Just so the parallels don't move if you touch them with your finger.

[Jon W]

I’d second the earlier suggestion of introducing a rod on the movable jaw side, but would recommend it be a bit of 12ga or so copper electrical wire. No substitution for a Kurt, but it might help your current vise behave itself a bit better.

[Harold_V]

If I got a used Kurt vise, would it still be as accurate as a new Kurt ?

Depends on what it's been through. My first Kurt is more than 50 years old and still does a great job. It has had no maintenance, not even the jaws reground. Second one is about ten years old, but looks the same as the day it was purchased. The paint isn't even scratched. Being used isn't a problem, but being abused certainly can be. From my training days, I can remember vise handles beaten flat by those who didn't have a clue about doing fine work (and used hard hammers instead of soft hammers). A vise like that most likely would be shot, not worthy of being owned. By the way, the vises I speak of were not Kurt---which had yet to be marketed.

H

[Richard_W]

You are looking for a starrett no. 54 hold down.

https://www.ebay.com/itm/255409157918?h ... Sw0BpiG~Cz

I have both a Starrett and Lufkin. I haven't used them in quite a while since Kurt vises have become common in shops.

Richard W.

[mcman56]

You are looking for a starrett no. 54 hold down.

Can you explain what these do? They just look like parallels.

[Lew Hartswick]

First, are you sure the side against the fixed jaw is true 90 deg to the bottom of the part being held (or for that matter sure the fixed jaw is perpendicular to the base ie. the table). Second, DON"T tighten the movable jaw TIGHT and then try to tap the part down. do it gentle bit by bit so the part can move.
...lew...