Threading 4.5 per inch

buggsy · Mar 23, 2017

Hi, I'm trying to cut 4.5 tpi on a 2 inch shaft, on my heavy ten SB, it's not coming out right. What am I doing wrong, and what's the solution?

Buggsy

Street · Mar 23, 2017

well you always do a light cut and check pitch before you get too far.... or use a bit of scrap as well.

Check the settings again, are the change gears set to metric? (end of lathe) that would be one of the first things to look at.
4.5 pitch is a little unusual i thought it went 2, 4, 6 etc.

i know some lathes do not go to 2 tpi. I used it for a dual start a while ago myself. 4 should be ok for most if not all lathes.

kitno455 · Mar 23, 2017

"not coming out right"? It will be hard for us to help you, with only that to go on. Is it left hand thread, is it the wrong pitch, is the thread form shaped incorrectly, is it double threaded? Give us more data.

Now, all that said, I'll hazard a guess- you are getting something like a 14tpi thread? That's because you are using the clutch and long feed instead of the half-nuts.

allan

weedy64 · Mar 23, 2017

A pic of your gearbox settings, end gearing, and or course the resultant thread would help us diagnose.

Hazzert · Mar 23, 2017

If your gearbox is setup correctly: Does your tool have enough side relief so it's not rubbing the flank as it cuts?

promacjoe · Mar 23, 2017

Street said:
Check the settings again, are the change gears set to metric? (end of lathe) that would be one of the first things to look at.
4.5 pitch is a little unusual i thought it went 2, 4, 6 etc.

4.5 is a standard pitch. and should be available on all South Bend lathes.

Do you have a single tumbler gearbox or a double tumbler gearbox . If it is a double tumbler gearbox, Did you replace the 20 tooth stud gear with a 40 tooth gear. if you did not, You will be cutting a 9 TPI. We need to see what your setup is before we can help. Otherwise we are just guessing.

stay safe and have fun.

Joe.

buggsy · Mar 23, 2017

Thanks for the replies, I found a thread on this site that said if you start on a number you need to continue with that number. I started on ! and it worked out fine.I tried to thread on my 16, but I needed to change gears on the stud, and I could not figure out how to do it. That's when I switched to my Heavy ten. I didn't need to change anything, just follow the same number route.

Thanks again
Buggsy

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Threading 4.5 per inch

buggsy

Plastic

Street

Hot Rolled

kitno455

Titanium

weedy64

Aluminum

Hazzert

Stainless

promacjoe

Stainless

buggsy

Plastic

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