Just got my first (second hand) leg vice (post vise). The jaws are set at quite a large angle when closed, (tight at the top, big gap at the bottom). Due to the nature of how it works, they are only truly parallel at one point.....this being on mine probably over 2 inches open.
It does need the grip and some of the sharp edges removing, as it is making lots of mean marks on my metal, so i was wondering should i start grinding the fixed jaw to make it parallel when almost closed, as i am currently working on fairly small stock and its just not holding it well enough.

Bit nervous of attacking my new toy!

Also it is on a stand, but currently not bolted down.....when it is, would this problem be compensated by the fact i could just tighten it a lot more?

During training i never really noticed or encountered this problem! :confused:

I'd recommend making yourself a pair of jaw inserts to cover the jaws. You can face the inserts with copper too if you want an even softer surface to prevent any maring.

IForgeIron > Blueprints > BP0358 Vise Jaw Protector

I agree with Justin - no permanent mods and can still hold a variety of sizes.

I did that to a 4" vise I had. I had made something in it and had used my 4 lb sledge. I bent them right at the eye where the screw goes through. I just took them apart, laid the bent one across a couple of pieces of steel and hit it with the hammer and straightened it out. I built up with welding around the eye and it never bent again. Of course I took it easy on the vise after that. You can straighten them without any grinding or special jaws though. If you have to heat it to straighten it I don't think it will hurt them because they aren't real hard steel.

It would be some work but you could make a jaw insert that pivoted like a power hammer flatter then your jaws would line up irregardless of the material thickness you were clamping. Also it would be an improvement for clamping a taper.

That's a nice Blueprint. For an even softer insert( like I use for holding a gunstock), You can take heavy leather dampen and mold the same way the Copper was formed over the jaws(once the leather is dried it will hold form. A good source for the leather is a weightlifters belt, often found at Garage sales for very little.