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View Full Version : Advice on repairing a machinist vise



Jim Doherty
10-30-2012, 05:42 PM
I have a vise that seems odd to me, looks like its an unfinished or messed up project.

I'd like to try to repair it. As I got it, the vise had no retaining plate and a bent, hacksawed screw that I don't think is original to the vise.

One odd thing is the moveable jaw sits 1/10th" below the top of the fixed jaw.

The lower portion of the moveable jaw sits 1/10th" below the "rails" that the retaining plate would ride against.

So if I use a flat retaining plate on the bottom of the moveable jaw, the jaw no longer makes contact on the vise ways but the top of the jaws match.

I made a retaining plate with a recess to keep the vise jaw on the ways.

http://i837.photobucket.com/albums/zz293/jcdoherty/Picture061.jpg


This picture shows the 1/10" drop of the jaw

http://i837.photobucket.com/albums/zz293/jcdoherty/Picture065.jpg


http://i837.photobucket.com/albums/zz293/jcdoherty/Picture066.jpg


The screw looks to be 1/2-13 tpi, 5" does anywhere sell replacements?

Could I make one out of stainless threaded rod from Grainger, or would I need to learn threading and make my own?

Another oddity, there are two holes partially drilled (pic 2) where I would assume a pin goes through to hold the screw to the vise jaw when the screw is retracted.

Why wouldn't the holes go through?


Thanks for any thoughts or opinions, Jim

Gary Paine
10-30-2012, 06:02 PM
Your questions leave me with a few of my own. Are the parts already hardened? These were usually made of tool steel and not quite fitted yet, hardened, and then ground to fit on a surface grinder.
The first issue is whether the threaded hole in the end plate lines up exactly with the hole in the movable jaw. If it does, you can proceed. If they mismatch by the tenth of an inch, you will have to add permanent shims to the bottom of the jaw.
Does the threaded shaft fit the threads in the hole properly? If so, 1/2 - 13 threaded rod is easily located and can be machined to fit.
Yes, normally there is a single hole with a set screw that has a pin end which engages a groove cut in the end of the shaft. It needs to be fitted well to minimize backlash. If the jaw isn't hard, the machining work can be done. When complete, the jaws can be milled down to flush.
Good luck.

Jim Doherty
10-30-2012, 06:41 PM
Thanks for the fast reply Gary

The threaded hole in the end plate exactly matches the hole on the moveable jaw when the jaw is tight to the ways.

The vise is hardened, I took a file to it and it skates off several surfaces.

I'm not positive about the size of the screw, 13tpi seems to match to me but all I have are HF thread gauges.

The thread OD is .495 and could be turned by a finger along the undamaged portion but also seems to have a tiny bit of play

I tried a piece of hardware store plated threaded rod 1/2 13tpi and it screwed in fully but had more resistance than the screw that came with the vise.

I'm not sure if that is due to the thickness or roughness of the plating or if the screw might be an odd thread that 1/2 13tpi could thread into.

Thanks, Jim

Gary Paine
10-30-2012, 08:30 PM
That makes it tough. Looks then like the maker forgot to provide for the keeper screw when he sent it out to harden. Three alternatives come to mind: Have the jaw annealed so you can finish it; Make a new jaw; Design a keeper with a slot to fit a grove in the new screw that wraps the jaw so pins or screws into the half holes can retain it. Unfortunately, the keeper will reduce the jaw travel by its thickness.
[QUOTE=Jim Doherty;I tried a piece of hardware store plated threaded rod 1/2 13tpi and it screwed in fully but had more resistance than the screw that came with the vise..

Sounds like that's the thread size. An adjustable die could smooth up the fit, but with regular hardware store plated stuff into a hardened hole, I think simple use will take care of that.

winchman
10-31-2012, 03:31 AM
I think there used to be a shoulder on one end of the screw to catch the pin next to the hole in the movable jaw. Much use with little lubrication probably wore the shoulder away to the point where it wouldn't work. In the last picture, you can see the rough area on the right end where the shoulder used to be. You might be able to drill and tap the end of the screw, and install a socket head cap screw and hardened washer to make it usable again.

Mcgyver
10-31-2012, 08:28 AM
I have a vise that seems odd to me, looks like its an unfinished or messed up project.


I'd agree with that. This is a common apprentice type project and not everyone who ever got a tool & die apprenticeship was good.

make a screw and use it ....or if its out o sq or you can't live with the height difference, scrap it. Its just a drill press vise, doesn't look like a prize and there's no hint of you knowing the owner or it holding sentimental value.

I agree with Gary on using threaded rod. being able to machine a thread is something you should not shy away from however its just not worth the effort with no advantage over ready rod. Sounds like you have a piece already. turn the one end to fit the movable jaw, and on the other weld/braze on thread onto a larger diameter cross drilled piece for the handle. Peened ends on the hand are a nice way to finish it. If the threaded rod is tight, use a bit of fine lapping compound with a piece of rod and that will take care of that; just make sure you clean it all afterward.