Looking for an Acme thread 7/8" -4tpi thread nut

[casaid1]

Hi everyone. I have a 1940s-1950s "The ridge tool company" (not a typo) 4-1/2" bench vise. My grandfather bought it new and its the only thing I was able to get of his when he passed. I'd like to restore it and have already ran into a snag. Most of it is there except the swivel base and the drive nut for the lead screw. The problem is its 7/8" -4tpi acme thread. Does anyone know where I can get a nut for it? There was a previous thread here about a 7/8" -4tpi rod being needed but there wasn't any closure to that thread.
Thanks everyone.

 

[eKretz]

Buy a tap and make a nut. Or make a tap and make a nut. Or have somebody else do one or the other.

 

[true temper]

That looks like square thread, not acme.

 

[neanderthal mach]

I thought the same as true temper, So is it square or ACME?

With a quick search 7/8" x 6 tpi ACME seems to be the standard today. 4 tpi appears to start at 1". My guess is that was a non standard screw and nut size used by the manufacturer. They do that sometimes to lock in where spare parts can be obtained. Fine if the company remains in business, a royal pita when they don't. Overall it might be a whole lot cheaper to replace both the screw and nut to that off the shelf 7/8" x 6 tpi. Or do what eKretz just said.

 

[eKretz]

Does look closer to a square thread to me also.

 

[john.k]

I was given a locally made Dawn vice ............quick check of the Dawn parts list...the screw is $200 the nut is also $200........i suspect someone stole the screw and nut to replace theirs......anyhoo,cost wise uneconomic.

 

[john.k]

Generally the screw is either square or butress............even junk $40 Chinese vices have square threads.

 

[dalmatiangirl61]

For a vise, would it make a difference if you used acme thread vs square thread? Why not just use 7/8-6 acme thread/nut, both available off the shelf.

 

[casaid1]

For a vise, would it make a difference if you used acme thread vs square thread? Why not just use 7/8-6 acme thread/nut, both available off the shelf.

Its my last option. But a viable one. Id like to keep my late grandfathers vise as original as possible.

 

[BT Fabrication]

bring the screw to pretty much any machine shop, have it clean clean, and have someone make it to fit what you currently have. might be a few hundred bucks to do.