Repair a quick release vice

[RussellT]

I've been trying to fix a large steel bodied quick release Record vice and I'm having trouble.

The problem is that as I tighten the vice the quick release moves and the nut jumps out out of engagement.  Unfortunately I'm not the first person to attempt to fix this and I'm not sure that it is complete.

I have tried adjusting the spring pressure as far as possible with no success.  Is spring pressure the only way that the nut is kept in engagement with the screw?

Here are a couple of photos.  I'd be grateful for any suggestions.


Russell

[tekfab]

Mmm, well before faffing about with spring pressures 1) Clean the bloody thing ! thats mingin !  2)Straighten the bracket (flat bar) before trying to re-assemble  3)check for missing parts 4) Check the internet for a picture of how the assembly should look Then re-assemble with some new grease and a bit of TLC !

If you can't find a picture then i'll unbolt my vice and take a couple of pictures for you.

Mike

[RussellT]

1) Clean the bloody thing

2)Straighten the bracket (flat bar) before trying to re-assemble

3)check for missing parts

4) Check the internet for a picture of how the assembly should look Then re-assemble with some new grease and a bit of TLC !

Thanks Mike

Done all of them, it may not look it in the photos but all the important bits are clean and have clean grease, actually made a new flat bar as I suspected the one I had was not right.  (It was 25mm (and I expected imperial measure) wide and looked unworn and I thought making it slightly wider may contribute a wedging action - it helped but not enough)  I can't find a diagram as it's ancient (No35) but I think it's complete and assembled correctly - but I'd welcome confirmation of that.

Russell

[tekfab]

If you send me your email address i'll send you the photo's, saves me uploading re-sizing downloading etc etc 

tekfab@hotmail.com

Mike

[tekfab]

Decided i need the practice in posting pictures !  Its a Record No 36 so should be more or less the same.

Mike

[RussellT]

Thanks Mike

I see some minor differences from the one I have - a couple of lumps of reinforement for two of the bolt holes, the fixed lug for the flat bar is cast in, and the shaft of the half nut is round not square.  From that last one it seems to me that there isn't any wedging action - I thought that might be between two flat surfaces - one of which is the shaft of the half nut.  In that case it's the spring that keeps the half nut against the thread. 

My current suspicion is that the thread is worn so that the thrust face of the buttress thread is no longer square and so loading the vice forces the half nut out of engagement.

Any other thoughts?

Thanks again - going and taking the workshop to bits is beyond the call of duty.

Russell

[tekfab]

Russell,  the flat bar should be on "top" of the half nut operating rod, i'm guessing that there's a missing bracket/plate that locates the flat bar and stops it from going "over centre".
The torsion spring operates by holding the half nut in engagement and by operating the lever you release the half nut allowing you to free slide the vice.

Mike

[RussellT]

Hi Mike

I think the mechanism is all there.  It looks very similar to the mechanism on your vice.  One edge of the flat bar sits in a notch in the half nut and the other edge is trapped by a screwed on tab of metal - cast on your vice.

The mechanism seems to work OK until I put some pressure on the vice handle - then the locking lever starts to move until it unlocks.

Russell

[chipenter]

I have a similar vice if it pops at all positions then it is likely to be the half nut ,mine had a wear ridge on the nut scraped it out with a scraper made from a 3 corner file its fine now .

[S. Heslop]

Might sound silly, but make sure the nut is the right way round. I reassembled my vise with it back to front and it took me a while to notice since it only jumped out on heavy clamping.

[RussellT]

It pops at all positions - but some easier than others - and it can't be assembled wrong way round.  The half nut appears to be worn to an angle but the screw less so (photos below).

If that is the problem my options appear to be, to try and clean up the thread on the half nut, to pack the halfnut up to do away with the quick release or to modify the release mechanism so pressure from the screw can't unlock it.

Any other thoughts?

Russell