record vice keeps jumping and clicking

[Selwyn]

When I wind it in or out it seems to want to jump the screw. Its a quick release vice and seemingly the flat bar underneath seems to be stalling it - bought it from a car boot so not sure how its meant to run.

When I give it a tug it will settle back and screw again for about two rotations and then jump again. Is it missing something?

 

[Phil Pascoe]

It probably just needs a good clean - the half nuts clog up. If you remove the pin that holds it together you can pull it apart. Get it all cleaned up, then look for anything mechanically adrift - they're quite simple really. Replace the pin with a nail or something easily pulled out if you ever need to again - it doesn't serve much purpose really.

 

[bugbear]

It's easy to test if the screw thread is worn (which is sadly common). It is normal for there to be most wear
on the screw when the vice is holding nothing (or at most 1/2" item). So test this size for slipping.

Then test with a 6" piece of wood. If the vise still slips, it ain't the screw. It is (nearly...)
inconceivable that anyone would manage to wear the whole length of the screw.
Could be the half nut, could be the spring.

But if the vise doesn't slip at 6", it's the screw.

BugBear

 

[Racers]

If the vice is sticky the half nut will slip, it and the thread are angled so any friction will force the nut up the slope.
Clean the bars and use the quick release leaver to adjust it then turn to tighten.

Pete