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Record 52 vice

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Kidneycutter

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Trying to revive this old vice looks like an early one. It won't tighten and just slips. I've tried in different locations but still slips. I think there may be something wrong where the half nit is located . Any thoughts?
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Chippymint

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I've got a couple of these and had to completely strip them down and clean etc. Obviously I can't see your detail but my suggestion is to follow some logics.

Make sure the main support sliding bars and the cast iron guides are not too worn. If they are you will get a lot of up and down play when the vice is coming out/in which then releases the half nut pressure on the worm thread - hence it will play up when trying to tighten or release. Some, you can rotate the main bars just 90 degrees - this can take out some of the play.

If the worm drive and nut is badly worn this too will cause an issue. Not much you can do though unless you find another vice and try swapping parts etc. The threads are normally worn over the first 2 to 4 inches where it's used most. If you pull it out as far as possible and it does not release, it's likely that the first 2 to 4 inch threads are worn.

What you can do and is one of the main problems, I found, is the quick release housings spring tension is insufficient. This is what holds the half nut against the worm drive shaft. Assuming your spring has some life left, you really have to make sure there is more than adequate tension. The tension is achieved by coiling the spring and locating the spring in the release mechanism bar slot. It's not easy but if you fit the spring easily it won't be enough, move it another 180 degree and possibly one more, and try it, but not over the top to cause breakage. Its easier if you can do this when it's fitted to the bench.

Sorry if I've misunderstood. If you need more help suggest you post some more photos.
 

Kidneycutter

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Thanks for your reply. When I tighten the half nut pushes down and then jumps the thread ...spring tension I guess?
The spring is in the half nut shaft and not in the front mount. I've not seen this type before.
 

Nigel Burden

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If you click on the link that I posted above and scroll down the page, you will see an identical vice. The photo shows the QR tension spring of the half nut fitted around the shaft of the half nut. I would imagine that the spring has become weak with age.

Nigel.
 

Kidneycutter

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Post a photo of your spring and release lever.
The second photo shows the half nut and Spring. The vice no. Is 674409 no.52 would be interesting to see the original Spring, set up. I'm pretty sure there's not enough tension in the spring and this is causing the thread to ride over. However, there is quite a big slot in the half nut for the bar could this cause the slipping, you can see this please follow n the photo too.
 

Nigel Burden

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The bar that fits in the half nut slot has an offset hole where the screw goes through to fasten it to the QR lever. It is easy to get this wrong, although it does look as if it's lining up correctly in your photo. The slot in the half nut doesn't look overly large to me.

Nigel.
 

Chippymint

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If your assembly is the same as in the photos Nigel refers to it's very different to mine. They must be different models so I can't compare.

My guess is your problem is a spring tension and wear and tear issue on the main worm assembly. I would dismantle and give it a proper clean then check for obvious wear on the male and female threads - you could use a vernier gauge to help pin point the main area. Assemble it and check it's ability to clamp and not jump along the length of travel. It will probably jump in the first 4inches of travel.

In addtion to what Nigel says, my guess is the spring has lost its strength. You could try spacers under the spring to add more pressure or try and find a replacement as near as possible. I have seen springs in places like Army Surplus stockists before but no idea where to find one otherthan this forum or getting another vice and making a good one from two.
 

toolsntat

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Have a look at the state of the thread at the furthest (least used) end and compare with the rest. It is not uncommon to find that the wear has reduced the "hook" of the thread to a near vertical shape along with the possibility of the half nut doing the same.
The design of this "hook" shape makes it hard for it not to work when in a usable condition.
Due to the "hook" design, if it's anywhere near catching hold, further turns serve to only make it lock tighter together.
If it is only worn on the outside periphery, this could be a result of compacted dust n muck in the half nut.
It's important to unclog any of this compacted stuff and maybe it'll be enough for it to partially work again.
Cheers Andy
 

J-G

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I'm somewhat surprised that no one has yet called the thread by the correct name. It's not a 'Worm' it's a screw thread correctly known as an 'Undercut Buttress' and as toolsntat has mentioned is prone to hold on to the compacted 'muck' which can stop the mating nut fully engaging. Once you understand what is supposed to happen it makes it much easier to see how the system can break down and therefore correct the problem.

It is also possible that there is wear on both the screw and the nut which would naturally also cause a breakdown if it went as far as no longer being 'undercut'.
 
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