52 1/2 vice problem

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sunnybob

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My 52 1/2 record vice is not yet 6 years old from new. I dont hammer the bar.
Yesterday as I was tightening up on some wood the nut slipped over and the vice went loose. Tried again. Same thing. Everything is in place, it works normally except for that extra "tug" which lets it slip loose.

I've taken the half nut off and nothing is obviously broken or worn out.
Any suggestions please?
 
My guess would be if the half nut's cage is not loose or the return spring slipped a tooth which the does not create enough pressure to hold the half nut.
 
The half nut cage's bolts were not "loose" but were easily undone with the slightest pressure on the spanner.
I put it back and its still slipping with almost pressure exerted. I have had a closer look at the spring in the front plate and there appears to be adjustment slots. Maybe the spring has weakened? Is that likely after only a few years of hobby use?
Now to go surf and find out how to tighten that spring.
 
I'm in trouble.
I tightened the QR spring to the point that I can no longer move the lever by hand, and the vice still slips after only moderate pressure.
I've tried it in different spots so it has to be the half nut at fault.
I can be sure there isnt a spare on this island, and at the moment all post is suspended, and even when it isnt its 2 weeks delivery.
 
Have you cleaned the half nut and screw?

Pete
 
Pete, yes, wiped all the crud off, it all looks clean and no obvious damage.
Just found a new nut at Knightons, They want 45 quid for one, plus shipping to cyprus. I only paid a 110 for the brand new vice about 4 years ago.

Looks like I will have to jam the thing fully closed and lose the QR function.
 
I've now removed all the QR stuff. That can be bagged for possible future reinstallation. I've used 2 x 14 mm allen bolts across the cage to keep the nut engaged. The vice will now hold the pressure I normally apply. The cage is only bolted on one side. If the metal gives way later on I can make a bigger cage.

I've emailed the on island retailer, he has been good in the past ordering in parts.

Its a nuisnance losing that function, but I'm not going to pay 60 quid plus for it.
 
Does it occur in the one position(where you have used it most) or when in any position along the thread?
The thread and half nut should have a POSITIVE hook to draw the two parts together and this is the bit that when worn generally causes the jumping .
With this feature, regardless of what happens to the parts around it, the two parts cannot slide out and in fact can only draw themselves tighter together.
Cheers Andy
 
Andy, No hook that I can see. The coil spring on the face plate keeps the bar under tension pushing the half nut up against the thread.

I tried at three separate openings and fully closed, which is where I would never normally use pressure and the nut slipped on each, almost as if there was a clutch to prevent overpressure, but there isnt.
 
sunnybob":12jap07g said:
Pete, yes, wiped all the crud off, it all looks clean and no obvious damage.
Just found a new nut at Knightons, They want 45 quid for one, plus shipping to cyprus. I only paid a 110 for the brand new vice about 4 years ago.

Looks like I will have to jam the thing fully closed and lose the QR function.

Wiping off the crud, is not good enough, take a wire brush to the screw, a metal point to the half nut.
You could be surprised how well stuck, and how much crud is in there.

Bod.
 
sunnybob":22equjxp said:
Andy, No hook that I can see...

I think he means the thread form effectively hooks the thread and the half nut together - if it meets the half nut without hindrance under pressure it cannot jump out.
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It was a quiet sunday morning so I revisited the vice. Amazing how much I missed that QR function!

I soaked the half nut, spring, and castellated adjuster in a bath of white spirit while I cleaned the long thread. There was a lot of crud buried deep in the thread. I had to use a thin screwdriver in a piece of rag, and make several runs along the thread to clear it.
Then brushed the muck off the parts and reassembled..
It still slipped, but then I increased the spring pressure by one notch and yahoo, its working again =D> =D> =D> =D> =D>

It appears the problem was ground in muck on both screw and nut, stopping them from completely interlocking, but even then the pressure has to be just right. :roll: 8) 8)
 
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