Acme nut help

[Corset]

I have broken/worn out a brassthread nut on a vice. Its 1inch by 6tpi thread acme by the looks of it. Anyone know where i ca find another as i ideally need a steel one to weld back in place.
Everthing i find seems to be metric.
Sigh, hopeful
Owen

 

[Ttrees]

Snap, I've got some ACME from an old vice, and also some similar stuff.
I'd like to know also, for again.
Have you looked up Chronos UK?
Guessing those guys are probably the closest thing to McMasterCarr in the EU?

 

[TFrench]

Chronos in my experience are just resellers of far eastern stuff. There are some big players that have a range like McMaster - Zoro, Cromwell, MSC, Brammer - but they are harder to buy from as a private individual than McMaster.

To answer the OP question - is the acme thread ok and just the nut worn out? If the thread is worn out it could be easier to swap the whole lot to a trapezoidal nut and screw. I've done that in the past with a milling machine vice. If its just a nut you might be best off finding a machinist to thread one?

 

[Fergie 307]

Try Fastenright Ltd. They do all sorts in acme threaded rod and nuts in imperial.

 

[Fergie 307]

Just an observation but for best wear you really don't want the nut to be the same material as the threaded rod, it will accelerate wear, that is why they usually use a bronze nut on a steel thread. Might not be an issue for something like a vice, especially for occasional use, but something to bear in mind.
Also need to think about how you mount it. If the vice body is cast iron then welding a steel nut to it really isn't a good idea, very unlikely that the resultant weld will withstand the forces involved. You would be better off to try and mount it in the same way as the original part. The normal type of vice nut is usually a square or oblong threaded section with a round stub bolted into the vice body. In that case you could get a suitable sized rod welded onto an acme nut, then machined to replicate the original part and bolt it in.

 

[ChaiLatte]

Try Fastenright Ltd.

1"-6 ACME nut in brass only here:

https://www.fastenright.com/general-fixings/hexagon-acme-threaded-nuts/n29
It is big enough so that it would be possible to bolt two pieces of steel flat bar to it and weld those to the main structure if required.

 

[eribaMotters]

Fergie 307, as regards wear, I believe there is a ratio between nut thickness and the thread diameter. If the nut thickness is kept within the ration then the nuts thread will wear before the leadscrew thread. I though this ratio was common across nuts and bolts for this reason.
When the nut differs in material the ratio does obviously not apply.

Colin

 

[Fergie 307]

1"-6 ACME nut in brass only here:

https://www.fastenright.com/general-fixings/hexagon-acme-threaded-nuts/n29
It is big enough so that it would be possible to bolt two pieces of steel flat bar to it and weld those to the main structure if required.

I would still avoid welding to cast iron if possible. If the vice is steel that's another matter. I would probably look to silver solder/braze a suitable piece of brass to it, then machine to suit. A photo of the old part would be helpful.

 

[Fergie 307]

Fergie 307, as regards wear, I believe there is a ratio between nut thickness and the thread diameter. If the nut thickness is kept within the ration then the nuts thread will wear before the leadscrew thread. I though this ratio was common across nuts and bolts for this reason.
When the nut differs in material the ratio does obviously not apply.

Colin

The other advantage is that if some hooligan overtightens the vice the nut will often let go before doing serious damage to anything else. I have a big old machine vice where this is exactly what has happened, the spigot on the threaded nut that enables it to be bolted to the vice has sheared. Lovely old Victoria brand 6inch swivel base vice. Only paid £50 for it so still a bargain. Unfortunately a square as opposed to acme thread so will have to make up a tool and get a lump of bronze to machine a new one. On the to do list for now

 

[Corset]

Its a colt vice so seems part welded. Had to order from the statesmimomum order was£150 from above. It may work or it may not. At least i will have some new nuts, haha