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Zeroclick

Vice jaws will not close tight

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Hi All,

So I have a small post vice that I have finally got back together but the problem is that when I try to close the jaws they close to about a 20mm gap and then keep popping back open and wont close anymore. 

I have checked nothing is catching and that the screw box is original and not catching because the screw is to long and everything seems ok.

I wondered if anyone else had come across this or had any ideas.

Cheers,

Luke

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So...you get down to about 20mm and it pops all the way back out?  First thing I'd look at is whether the nut is so worn that the screw is barely making contact.  It might grab just because the screw is at the right angle until it reaches a point and then the screw re-centers in a severely worn nut and will slide all the way back out under spring pressure.  Might not grab again until you can make the screw skew enough to get a little bite in the now-oversized nut.

And if the nut is not worn, it might simply be for a larger screw and someone "married" parts from a different vise.

But I'm just guessing because it's not in my hands to see what is really going on.

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No it pops just a tiny bit back to the 20mm mark and then if i tighten just does that small pop.

It is very odd.

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20 mm is in the sweet zone for large amounts of wear. Most vises see regular use in that zero to 1-1/2" zone. Is the screw more worn in that area our are any of the threads missing in the screw box? That would allowing it to slip in that area. If the threads are in good shape, and fully engaged they would not be able to slip. A few pictures of the screw box threads and male threads on the handle may help with diagnosis. 

Have a good night,

W

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I have just tested it out tonight and it seems to hold but then if you tighten it so it holds so nothing moves.

It pops again or just doesnt seem to be holding very tight a little tap of the material and it pops out.

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The threads are worn out. It would never "pop" if they were in good shape. Large threads like that can have enough engagement to move an item, but not enough to actually hold any pressure.

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Have you tried with a thicker washer in front of the moving jaw?  (Change where the screw engages the screwbox.) Stop gap as it will probably need a new screw/screwbox soon.

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