Acme Threads

[TomG]

Cutting Acme threads is pretty much the same as cutting Unified threads . The only real difference is that the compound is set to 14 1/2º instead of 30º and you can't take as deep a cut because there is more of the tool in contact with the work. If you can cut a Unified thread you can cut an Acme thread, there's nothing magic about it.

Tom

[EdK]

(09-26-2012, 09:20 PM)TomG Wrote: Cutting Acme threads is pretty much the same as cutting Unified threads . The only real difference is that the compound is set to 14 1/2º instead of 30º and you can't take as deep a cut because there is more of the tool in contact with the work. If you can cut a Unified thread you can cut an Acme thread, there's nothing magic about it.

Tom

I think I've read that with acme threads you feed straight in rather than at an angle like you do with a Unified thread. Is that true?

Ed

[TomG]

(09-27-2012, 05:53 AM)EdK Wrote:

(09-26-2012, 09:20 PM)TomG Wrote: Cutting Acme threads is pretty much the same as cutting Unified threads . The only real difference is that the compound is set to 14 1/2º instead of 30º and you can't take as deep a cut because there is more of the tool in contact with the work. If you can cut a Unified thread you can cut an Acme thread, there's nothing magic about it.

Tom

I think I've read that with acme threads you feed straight in rather than at an angle like you do with a Unified thread. Is that true?

Ed

Nope. The angle of the compound is just different, 14 1/2º instead of 30º. Square threads are fed straight in and those are a pain to cut. Sort of like parting with a twist.

Tom

[EdK]

(09-27-2012, 06:24 AM)TomG Wrote: Nope. The angle of the compound is just different, 14 1/2º instead of 30º. Square threads are fed straight in and those are a pain to cut. Sort of like parting with a twist.

Tom

Yea, I can see where square threads would definitely need to be fed straight in.

Hmmm, this talk about acme threads reminds me I have a project that is going to need an acme thread cut. I need to make a tailstock to use with my spin indexer for supporting work between centers. It probably doesn't need to be an acme thread but it'll be a good opportunity to get some experience in cutting them.

Thanks,
Ed

[stevec]

Ed, remember the nut that will follow.
It can be done though, I cut a new nut for the cross feed screw on my 12x36, came out pretty good ( it's left hand too).

[EdK]

(09-27-2012, 06:50 AM)stevec Wrote: Ed, remember the nut that will follow.
It can be done though, I cut a new nut for the cross feed screw on my 12x36, came out pretty good ( it's left hand too).

Good point Steve. The nut would be the challenge compared to the screw. I'll have to think about that one.

Ed

[Highpower]

Another possible option - just FYI.

Making Acetal leadscrew nuts the easy way - by Evan Williams

[TomG]

If the nut is large enough to get a decent size boring bar through, it won't be too bad. If not, you could always make the nut out of bronze and make a tap out of the screw. Real Acme taps are available as well, but VERY pricey.

Tom

[stevec]

If, your making a screw Ed, make it a bit longer and leave enough slightly oversize Like skip the final cut and you'll have the makings of a tap.

[EdK]

(09-27-2012, 08:48 AM)stevec Wrote: If, your making a screw Ed, make it a bit longer and leave enough slightly oversize Like skip the final cut and you'll have the makings of a tap.

That's certainly an option. Thanks.

I think I can weasel my way out of this though. I believe I have a piece of 1/2-10 left hand acme at home that I can use for the screw. That doesn't solve my nut problem though. I also have matching left hand acme nuts that I might be able to turn down and make a press fit into the sleeve. I'll have to start a thread about that project once I get to it.

Sorry to David for hijacking his thread. Shame on me!

Ed