can stub acme be changed to acme

[osiris999]

so at work tonight i had some parts that i thought needed 3 pitch stub acme threads. so i machines all of them with a 3 pitch stub insert. a guy at work just called me and told me they were so posed to be acme. from my understanding acme is just deeper. so can the parts be fixed if i chase them with an acme insert?

[307startup]

The flank angles should be the same, but the width of the tooth at the bottom may be different due to the nominal thread height. Compare taps or inserts to make sure. If you have to, look up the info on the manufacturers website.

[osiris999]

it can. first they wanted to scrap all the parts because our manual machines can only go down to 4 pitch. i guy who just started and knows nothing about programing and all managed to convince them to let him chase them in the cnc i made them on. they said it couldnt be done lol. took him 10 hours to do the 13 parts but he got them all.

[307startup]

What kind of CNC lathe are you using? Almost every CNC lathe I've ever ran across has the ability to rethread by picking up an existing thread. Hell, that's exactly what I did for a year at one company, chasing threads on components that had been damaged and wouldn't gauge, so they could be reused.

[aaron p]

Interseting. I was told on the Mazak E-410 Integrex I run at work that it wont pick up the thread if you take the part out and put it back in. Dosent know the start point I guess? I work at a huge oil field parts manufacturing plant and we do tons of different acme threads. Stub, Standard, Modified Brown Oil Tools Acme, and a bunch of others.