9/16" - 12 Acme L H threaded rod?

[Ultradog MN]

I'm working on a little shaper vise.
Jack asses in the past used it for a drill vise and drilled a bunch of holes in it and Fubar-ed the clamping screw.
I tried McMaster, MSC and general searches but am not finding much.
Any other places to look before I think about cutting my first acme threads in 50 years?

 

[Limy Sami]

Looks like it's time to grind up a screwcutting tool

FWIW I find the finer ACMES a lot easier (aka less scary) to cut.

 

[Phil in Montana]

You can machine one in less time than you have spent looking for one...

 

[Ultradog MN]

Yeah,
I'm thinking about making whole a new shaft.
But 9/16 diameter, with 6" of threads, on a 10" long shaft is gonna give me quite a bit of wow and flutter single pointing them.
Maybe if I contrive a follower rest for the job I can do it.
Thanks.

 

[Cole2534]

Yeah,
I'm thinking about making whole a new shaft.
But 9/16 diameter, with 6" of threads, on a 10" long shaft is gonna give me quite a bit of wow and flutter single pointing them.
Maybe if I contrive a follower rest for the job I can do it.
Thanks.

Couple thoughts-

Use an easier material, 1144 stressproof or maybe 4140L, to get your cuttibg forces down.

Setup your SG to grind a proper tool, mind the helix angle to guide your relief. Grind the tool narrow, allowing you to control thread width via the compound.

Acme is, IMO, much easier than vee to pickup. With that in mind consider doing it in 2 or 3 sections.

Acme is much more bark than bite when you able to break it down into small bites.

 

[Limy Sami]

Yeah,
I'm thinking about making whole a new shaft.
But 9/16 diameter, with 6" of threads, on a 10" long shaft is gonna give me quite a bit of wow and flutter single pointing them.
Maybe if I contrive a follower rest for the job I can do it.
Thanks.

Unless you HAVE to do it between centres, you're only going to have at the most 8'' out of the chuck and that will be supported by the tailstock.
Plus as has been said already, use a decent bit of steel (aka NOT rebar shite) and make a slightly thinner tool,

A tip, turn a narrow minor dia ? thread depth limit groove / spigot at the start and end of the thread so you'll know when you've reached the right depth, then if it's still cutting in the middle, take spring cuts.

P.S. Prepare 2 blanks before threading and you'll hit it bang on first go.

 

[Cole2534]

A tip, turn a narrow minor dia ? thread depth limit groove / spigot at the start and end of the thread so you'll know when you've reached the right depth, then if it's still cutting in the middle, take spring cuts.

Oh, that's a good one!

 

[Ultradog MN]

You guys were right.
It wasn't hard to make one.
Except those cheap acme gages only go as small as 10 tpi so I had to get the math from machinerys handbook.
As I mentioned, these are the first Acme threads I've cut in 50 years.
None of it difficult. Just had to get past the skeert.

 

[Limy Sami]

Well done mate, nice looking job, ............. see it's like riding a bike.