Smallest practical acme internal threading bar and inserts?

[Net30]

So Acme taps suck and I would like the ability to make internal Acme threads. I'm pretty well sorted on lay down external but internal quickly becomes challenging because the insurance is often bigger than the whole you need to machine inside. And then I've been looking at Top Notch and on edge. But then I get completely lost in the coding system and end up getting stuff that is not compatible with each other. So if you understand this can you explain it to me like I am five. What specific bar and insert would you use to make half inch acme internal threads?

I know many people would probably suggest high-speed, but it seems like I'm using Alloys more often than not seemed to destroy it rather quickly.

 

[mmcmdl]

Kennemetal Top Notch makes some small bars , but not sure off hand the minimum for Acme threads . I have the inserts for regular threading that would do 7/16s threads , maybe smaller . I would think the inserts would be the same size for Acmes .

 

[RaisedByWolves]

Kennemetal Top Notch makes some small bars , but not sure off hand the minimum for Acme threads . I have the inserts for regular threading that would do 7/16s threads , maybe smaller . I would think the inserts would be the same size for Acmes .

I’m thinking he’s going to need a solid carbide premade form tool to be that small and rigid enough.

And that will be pricy.

OP, what don’t you like about the acme taps? I’ve used them and yeah, they can be a ***** but a good sulfated cutting oil will make things easier.

You can also go up a size on your tap drill.

 

[DAT510]

Micro100 Carbide ACME cutters are ~$40 ea. It's hard to get small dia with a bar and inserts.

Standard-Threading Tools-ACME Threads

www.micro100.com

 

[Net30]

I’m thinking he’s going to need a solid carbide premade form tool to be that small and rigid enough.

And that will be pricy.

OP, what don’t you like about the acme taps? I’ve used them and yeah, they can be a ***** but a good sulfated cutting oil will make things easier.

You can also go up a size on your tap drill.

I went up like three sizes and used tap Magic and 1 1/4 was not likely happening again. Plus you don't have the control of changing the thread fitment.

 

[RaisedByWolves]

Micro100 Carbide ACME cutters are ~$40 ea. It's hard to get small dia with a bar and inserts.

Standard-Threading Tools-ACME Threads

www.micro100.com

That my friends is what you call a winner!

A whole lot cheaper than I was thinking.

 

[Ischgl99]

Micro100 make excellent tools, I have a number of different types that I am very happy with. I haven’t used their ACME tools, but I would expect them to work very well.

For the Top Notch ACME inserts, 10 tpi would be a #3 size insert. A #3 size internal bar has a minimum hole size of about 1.375”, so you can’t use that.

For laydown inserts, Carmex has a good threading guide. They show an 8U insert is available for 10 tpi, the 8U threading bar is an SIR0310K08U with a minimum bore of 0.35”. The threading inserts are on page a01-23 of the attached file, and the threading bar on page 46 of the other attached file.