ACME threading insert question

M

mswasty

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Hello,
I want to practice making ACME threads on my SB lathe. I'm looking at buying ACME threading inserts but I can't tell what the size is. I found many ACME thread spec sheets but how do I look at a cutting insert and tell what size thread it cuts. Here are some random insert specs and I'm not sure what it's telling me.

16NR 8ACME
16ER 8ACME
22ER 5ACME

Can you please let me know how to read these insert specs? I want to cut threads into a .50" rod, 10TPI.

Thanks
Matt
 
16 or 22 is the insert size

NR or ER is Internal or External Right hand threads

8 or 5 is the pitch (threads per inch)

Acme is, of course, the thread style

None of these will cut a 10 pitch.
 
Keep in mind, you need horse power to push these inserts for threading. My 9" SBL with 1/4 hp motor struggles cutting 10 p Acme thread. I start out with using a 12 p Acme insert and finish with a 10 p insert. Of course, in back gear, it' no problem but the surface feet per minute is low on smaller threads.
 
Good info. I have a SB 16" lathe. I hope it won't struggle to cut threads.

I double checked and the threads I need to cut are ACME 16TPI on a 1/2" shaft. Can someone please tell me what acme threading insert I need to buy. 22ER 16 ??

I really appreciate everyone's help! This forum is great!

Matt
 
Matt, that depends on the toolholder you are using. Sometimes things are brand specific, so if you could tell us the make and part number, or maybe a picture if it, it would help. There are simply too many possible inserts to guess at it.

Have you considered a hand ground HSS tool? The price would certainly be better.
 
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