DON’T DO WHAT I DID! I didn’t realize the dangers until I was done.

A vise’s jaw faces are supposed to be parallel, that is: perfectly flat when they meet. As you can see, this vise’s jaws weren’t.

Looking at the assembled vise, I could see the problem: the movable jaw wasn’t square with the long bar that slides through the fixed end of the vise.

At first I thought the vise was hopelessly ruined. Then I had a STUPID idea…

DON’T DO WHAT I DID. If your vise is out of true, talk with a blacksmith or other qualified metalworker. I could have injured or even killed myself.

So, as a warning to you, here’s what I did… that I shouldn’t have.

I noticed that the bottom of the movable jaw extended below the long bar, and that the base of the fixed part of the vise was also below the long bar. If I could rest a thick piece of steel in the space between those two parts, then over-tighten the vise, the movable jaw just might bend back into square.

So I cut a piece of relatively-thick steel to length, clamped the vise onto my woodworking bench, then used a long steel pipe as a ‘convincer’: a way to seriously over-tighten the vise.

It worked! I very, very gently over-tightened the vise, checking the bending of the movable jaw, until I was satisfied that the jaws were reasonably parallel. Luckily I didn’t bend the vise handle.

In hindsight…

Reflecting on the bending process, I realized WHAT I DID WAS VERY DANGEROUS: the piece of steel, and the whole vise, were under high pressures they were not designed to withstand. The piece of steel could have bent and shot out to hit me in the eye, face, hands, or wrists, possibly cutting a vein. The piece of steel or part of the vise could have snapped off, sending a steel shard toward my eyes, face, or hands, with the same, deadly result. I basically had a hand grenade on my workbench, with only safety glasses to protect me.

The irony is, I may have weakened the vise. Bend a paperclip over and over. Each time you bend it, it weakens a little more, until it breaks. In the same way, whoever abused this vise in the first place weakened the movable jaw, and by bending it back, I weakened that jaw a little bit more. …or not; I know next to nothing about metalworking.

If I really wanted to fix this problem I should have taken the movable jaw to a metalworker or blacksmith, who could have practiced their arts on it (heating & cooling, heating & quenching, etc.) to make the movable jaw square again without weakening it.

Well… lesson learned, onward in the next post.