Bench vise repair

[smfr]

I picked up this Babco bench vise for $15 at an estate sale:



but after getting it home and taking a closer look, I find that the outer jaw is loose on the shaft (not sure what this part is called; the lower bar that slides in the base), so when I tighten it up, the jaw pivots and and the jaws no longer mate nicely:



I can't figure out how the shaft is held in the outer jaw; there are no pins that I can see, so I can only assume that the jaw was cast round the shaft.

I'm pondering whether it's worth fixing this, and if so, how.

I could drill through the outer jaw and shaft (just under the '5' of 35 on the casting) and put in a pin or two. If I did that, would the pin(s) hold out? If I used drill rod for the pin, should I harden it? There's a lot of force when tightening down the vise, so the pins might just get chewed up.

The other alternative is to live with the flex, and just make some new jaws (I was thinking of using Al, since I want soft jaws most of the time) that take the angles into account. I could tighten the vise down on the jaw parts, then mill a slot, then remove some material to make mating jaws.

Thoughts?
Simon

 

[krv3000]

hi well i can see a pin

 

[smfr]

Right, that's the split pin that holds the lead screw in. But the flex is between the jaw and the shaft, see attached image.

 

[chuck foster]

hi simon
could you possibly braze or electric weld the two parts together and then re-machine the jaw surface ?
if the two pieces are cast iron (i think they are) brazing would work but if you electric weld you would have to use nickel rod.

just a thought and i hope this helps.

chuck

 

[smfr]

I thought about brazing too. I can't get the pieces apart (I assume the shaft has some kind of notch on the end that the casting holds onto), so I can't get them clean, but maybe I can just get some solder in there to stop the movement? I guess if that fails I can try pinning.

 

[d-m]

Simon
remove the movable jaw square the jaw to the (for lack of better terms) the guild that goes into the main casting and pin it. If there is room, pin it from the bottom but it will need to go through the guild and into the jaw casting it wont work if it just goes through the bottom of the casting and the guild and doesn't have support on the top of the pin. I wouldn't think its a hollow casting.Be careful not to use to large of a pin or it will crack don't worry about harding the rod but drill rod will be fine make it a press fit. Also if there is as I suspect a gap between the jaw casting and the guild try to fit a wedge in there use your Favorite BFH to drive it in after the pinning is done. Sorta how i would try but its hard to tell the hole story from a pic,
Daveer

 

[Mainer]

Let me preface this by saying I'm not a welder of any type, so this may not be accurate. It does however match up with what I learned in Strength of Materials class an uncountable number of years ago.

I've read that welding cast iron, no matter what kind of rod you use, may cause cracking unless you heat the whole piece to 1300 degrees before welding. It's a problem because c.i. has a small elastic range and is brittle. Where mild steel would distort, c.i. will break. Brazing is better because the heat is not as localized, but preheating may still be a good idea. FWIW.

As for getting it apart: is there any indication that bottom guide could lift up and unhook from the front jaw if you take the leadscrew out? If the front jaw is cast around the part I guess you're doomed to pinning it. I think I would use real dowel pins, hardened and ground, rather than drill rod, and get the correct reamer to give a proper fit. You could also get some thin-consistency metal-filled epoxy, if there is such a thing, and pour it into the cracks after pinning. You might want to consider drilling a small hole in the front of the jaw and injecting epoxy into that space too.