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I have a bench vise that can rotate something like 270°. The problem is that the clamp that's supposed to stop it from rotating seems to only work in one direction. I can crank as hard as I can on the handle - really reefing on it. Yet, the vise will still rotate.

Here's a picture of the vise with the handle in question:

Craftsman vise that twists too much

On the bottom there's a square head on the bolt that looks to have an ACME thread. My thought was that I could just grind down a bit off the end of the bolt and that should let me tighten it a lot better against the base of the vise. Does that seem like a bad idea? Are there better ways to keep my vise from rotating?

Edit

Here's the bolt and the underside of my vise:

Bolt before I cleaned off the rust Underside of vise

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    Funny, I was just dealing with the same issue on an old vice I was given. In my case the bolts would spin and never tighten. They just needed some cleaning up. Have you flipped it over to see whether the bolt heads still rest on the base and haven't pulled through to the vice seat? – isherwood Oct 30 '17 at 21:07
  • Is there a washer under the head of the bolt (hidden here) which gets deformed and must be replaced or at least flipped over? Or does the head of the bolt get deformed and so the bolt must be replaced? – Jim Stewart Oct 31 '17 at 10:46
  • @isherwood I've added some photos. Looks like it still rests on the base, but it only clamps against the outside lip (not much of one on the inside anyway) – Wayne Werner Oct 31 '17 at 19:02
  • @JimStewart no washer, and the head of the bolt looks ok. There's definitely some wear on it, but it's not that bad. – Wayne Werner Oct 31 '17 at 19:03
  • If you would clean the rust off the bolt and lube it and lube the threads in the clamping nut (with the handle), would the bolt go further into the clamping nut? – Jim Stewart Nov 1 '17 at 1:09
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Rather than trying to shorten the bolt, what about putting a spacer washer under the clamping nut? You might do this as a diagnostic test to see if the present inability of the clamping bolt to hold the vise is due to the nut "topping out". Of course, if there is not a washer in the original design, there may be a reason, such as, a washer there might jam against the bolt and impede release when the nut is loosened.

I would make measurements of the length of the bolt and of the space inside the nut to see if this could allow the bolt to go farther inside. Maybe the nut is corroded inside and is binding early and so not clamping effectively.

Is it possible to improve the threads of a bolt-nut combination by applying an abrasive paste of suitable grit size to the threads and working the nut back and forth over the bolt?

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  • It looks like this was the most accurate - I had cleaned the bolt off (quite a bit of rust) and it seemed to clamp better, but I was still able to weeble-wobble the clamp and it would come loose. I pulled the nut off and stuck a couple of drops of 3-in-1 oil and now when it clamps down I can really clamp it down - shoving the vice back and forth doesn't appear to loosen the clamping action at all, or at least much less than before! – Wayne Werner Nov 1 '17 at 13:09
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Your idea of grinding a few threads from the bolt seems to be on the right track. In that photo, I wondered if the bolt was bottoming in the handle nut. Of course, if you grind too much off, it's not an easy task to replace the lost threads.

As an alternative, consider a shim of sufficient diameter to engage the entire bottom plate of the vise with sufficient thickness to take up the needed gap in the clinch bolt assembly.

If you're handy with a welder, build up a bead of weld on the edges of the bolt that engage the slot and gain the take-up in that manner as another option.

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  • When I pulled it off, it's definitely not bottoming out - there are at least 3-5 threads inside the handle nut that showed no signs of wear – Wayne Werner Nov 1 '17 at 13:02
  • I did entertain the idea of putting some kind of ribbing along the clamping surface(s), though it seemed like that would mostly just result in wearing out the surfaces a bit more when I reposition the vice. Then again I don't do that all that often so it may just not matter. – Wayne Werner Nov 1 '17 at 13:10

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