I bought an old post vice in fair condition but missing the spring that opens the jaws. The jaws are about 5 inches wide.

It's a little rusty but nothing is frozen. The screw looks in fair condition, but the spring that opens the jaws is missing.

I have a source of new leaf spring material, but not sure what size to buy.

I'd like to get in the ball park as far as size and would appreciate any suggestions or help available.

thanks

I have made several in the past. I think 2" from a small single axle trailer is what I used. When I get to the shop I will measure. Its just wide enough to bend the sides over at the bottom to keep it from slipping of the leg.

John

spring steel is not required, mild steel will work for that low stress application!

So will a coil spring. While not traditional looking they work very well and last a long time, are cheap and available at your local hardware store.

I just used an old leaf spring from my stockpile. About 1 1/2"X 3/16" and forged thinner at the top to fit into the collar. It isn't critical and depends somewhat on the size of your vise. Whatever you have handy... use that.

If you would rather buy than build, when I was looking around on eBay I found some "poor boy blacksmith tool" replacement springs. Just type in 'pose leg vise spring' and you should get some results.

Here are three results that came back when I searched just now.

As Thomas said, mild steel works quite well - especially if quenched in "Super Quench" brine solution and left untempered. I have a vise that I repaired with that method about 20 years ago and it has held up the entire time without taking a set or breaking.

If you do use 5160 spring steel, it doesn't need any heat treatment beyond normalizing. It will have enough springback without hardening and tempering.

Many of the old vise springs were fishtailed at the bottom. I've done it with my cross peen. Then, the tail is folded back on itself to provide extra thickness. After that the extra material either side, the "tabs," are bent at right angles. The shut from the fold is outside the bends.
Turley Forge and Blacksmithing School : The Granddaddy of Blacksmithing Schools

I have an old one that is frozen up pretty rusty but it looks like it would work. any one ever get one of these freed up after it set out side and rusted up ?

Put it on the forge and get some heat in it, then soak in diesel or some other penetrant if necessary and it should free up

Thanks John I will give that a shot. I think it will fit in my forge . How much heat do you think ? Just a mild heat or do I need to get some color ?

My two cents........

I use "Fluid Film". Works like a darn on rusted things.

I have made several in the past. I think 2" from a small single axle trailer is what I used. When I get to the shop I will measure. Its just wide enough to bend the sides over at the bottom to keep it from slipping of the leg.

John

Hey john my name is martin and I have a post vice with no spring I,ve tried several attempts at fabricating a spring for it but every one has broke. How can i temper the steel so it dont break?

Hey john my name is martin and I have a post vice with no spring I,ve tried several attempts at fabricating a spring for it but every one has broke. How can i temper the steel so it dont break?

Heat it evenly to non-magnetic, then let cool slowly in still air. Done. This is called "normalized". To determine non-magnetic get a ceramic magnet, I use a doughnut magnet (from Radio shack, 5 for $3) and hang it from a thin wire, like a strand from inside a network cable or phone cord. If the magnet is attracted the steel is magnetic, if the magnet swings naturally it is non-magnetic. This temperature is about 1400F.

This is suitable for mild, a36, coil and leaf spring steel.

Phil

What Phil says, a properly designed post vise spring doesn't even need to be hardened and tempered!

I just made another PV spring recently myself and used a medium carbon steel strap I had to hand and just normalized it. Works great!
(The one before that was leaf spring, again just normalized, the one before that was mild steel,....I like buying them without the mounting bracket and spring cause I'm cheap and then I get to make them to fit how I'm going to mount them rather than change what I'm mounting them to.)

BTW telling us how you did it when you had the breakage issue can help a lot in getting a fix

When I've made things of spring steel that had to flex, any cooling beyond air cooling seemed to result in breakage.

I am looking for someone who will make and sell quality post vise replacement  springs. I use to buy from poor boy , and did for several years.   Thanks for any information. , Rod

Welcome aboard from 7500' in SE Wyoming.  Glad to have you.

If you put your location in your profile we can give better answers to your questions.  A surprising number of answers are geography dependent.  This is a world wide forum and we don't know if you are in Timbuctu, Tasmania, or Tennessee. 

You generally don't need much of a spring on a post vise, only enough springyness to move the jaw back from vertical a bit and then gravity takes over.  I have been told, but have never needed to try it, that mild steel has enough spring to work.

"By hammer and hand all arts do stand."

Welcome from the Ozark mountains. I have to ask what do you need with a bunch of post vise springs? If my memory serves Poor boy (Ken) passed away in 2013, have you not needed springs since then? Also there are several sizes of springs to fit the different makes & sizes of post vises. Did you read through the posts prior to your reply? Making post vise springs is very easy. One doesn't even need a forge. My first spring I made was using an A/O torch for heating the stock to shape it.

I can't control the wind, all I can do is adjust my sails.