.750-24 UNEF-3A Thread question

[cbailey1956]

Hello, I am going to thread a barrel for the Silencerco ASR muzzle break and pulled up their spec sheet for the fit. I am a home hobbiest and normally cut threads using the 3 wire setup and common over wire guides. I have not been able to find any info on the .750-24 UNEF. What I have found is .750-20 UNEF. So where do I find the wire setup measurements? I did look in my machinists handbook but got confused. Additionally I noticed the Silencerco sheet has a 45deg angle on the thread angle which just further confused me. Am I overthinking the 45 deg instead of normal 60 deg thread angle. and where to find the over wire formula pls. Thanks, Craig

 

[Will Henry]

That 45 degree is a chamfer. If you look up the measurement for any other 24 tpi thread, for which you know the PD, you can calculate what you need to measure for your PD. I could go down to the shop and get it for you, but that would require me to get out of my recliner. WH

 

[LVLAaron]

Don't overthink it. The chamfers are a suggestion. I use the side of the threading tool. Don't sweat the wires (unless you want practice using wires) - turn it to fit your muzzle device.

 

[Fast14riot]

The notes give the pitch diameter above the print

 

[LVLAaron]

This will be helpful

UN imperial screw thread calculator

theoreticalmachinist.com

 

[DR_2297]

 

[geo.ulrich]

or a machinists handbook

 

[DaveTooley]

I have a 3 ring binder with print outs in plastic sleeves for all the threads I do.

 

[cbailey1956]

Thanks to all, I think what got me going was the UNEF class after the size. All the calculators I normally used did not list that class for 24 pitch, only 20. Found the UNS designations but got tooworried about it. I am trying to train myself since my deceased brother was a trained machinist for 45 years but never passed on much. Except fine whiskey sipping. Thanks again and my binder is loose leaf folders for now.

 

[SKWERLZ]

View attachment 1649931

That’s the site I use as well.

 

[TylerFromMS]

This will be helpful

UN imperial screw thread calculator

theoreticalmachinist.com

How about how far to go in on the compound?

Thread Cutting on the lathe

 

[cbailey1956]

Thanks for the replies, The depth of feed chart is very helpful. Printed it out to go with my other thread printouts.

 

[SKWERLZ]

How about how far to go in on the compound?

Thread Cutting on the lathe

Saved for future reference