Hi, I got an old Columbian, weighs around 30 pounds, that's jammed. I was trying to measure the jaw width so I opened it as far as it could go and lo and behold it is now stuck. All my Dad knows is that at some point a screw fell out but he does not know where the screw is. I have tried lubricating all around it but it is stuck tight. I was wondering if any of you experts had any ideas on how to fix it.

 

 

 

not an expert by any means, but look at the back end of the vice, opposite the turning handle, that whole bar should be a hollow section, i can kinda see the opening of the channel in the bottom from your first pic.  inside there should be the screw and a nut on some kind of mounting, that screw is what has come out of the nut and probably sagged down and cannot re-engage with the nut to allow the vice to close again.  get a screw driver in there to lift it up or a finger, or hold the vice vertically or whatever it takes to get the screw to re-engage the nut. Thats how my bench vice works (i dont have a columbian, but its the same basic configuration) and iv dislocated that screw a few times now.

 

however, if what you wrote means that your dad knows that a part has physically fallen out and he cannot find it, then you may just be outa luck =/

I would roll it upside down and check the threads, maybe theres some rust or some kind of buildup on the threads. Theres really not much that can go wrong with these.

If the screw(s) holding the nut/thread block in place have fallen out you should be able to see where it should be and wriggle the nut  into place (by turning the tee bar and jiggling with a screwdriver) and put in another, it may be an early thread form so unless you can match the thread exactly a piece of brass or aluminium may temporarily align the nut block sufficiently without damaging the threads.

 

Is this a known vice, was it formerly your fathers? I ask because there is a shiny section on the side of the channel section which could be a weld repair clean up. If that has not been cleaned up well it may be causing the jam, the vice only looks half opened in the pictures....

Good news I finally 'fixed' it. I took it totally apart, cleaned it, then put it back together and it works perfectly.

It was actually my grandfather's vise that's now my Dad's but he is letting me borrow it when I need it.

Note that jaw "width" is measured across the jaw itself and it's "throw" is how far it opens.