Single point threading

[Technical Ted]

I agree with those that suggest you try to figure out why you got poor results using the compound. I've done a fair amount of both internal and external single pointing and I don't ever remember using the cross-feed; I always use the compound set at ~29 degrees. Typically, you will get better chip control because you're cutting with the leading edge instead of both edges. But, whatever way you want to do it is fine as long as you get the results you're looking for.

Ted

 

[jpfabricator]

This is what I was getting before, same tool, same everything, different advance.
It's like its not threading, but wiping the threads off a little more with each pass.

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[neilking]

I had some success with just using the cross slide, but after reading about using the compound I've had success that way too.

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[tweinke]

View attachment 228076
This is what I was getting before, same tool, same everything, different advance.
It's like its not threading, but wiping the threads off a little more with each pass.

Sent from my SM-S320VL using Tapatalk

I have had the same result with the compound set at 30 or so but feeding in with the compound is ok. now I am wondering if I should measure the angle and be sure it is actualy between 29 and 30

 

[mikey]

Have a look at this: http://www.mmsonline.com/articles/threading-on-a-lathe

 

[willthedancer]

I have some thoughts, questions, and a suggestion.

Metric or USS?
I don't know zip about metric lathes.

If USS, how many threads per inch, and what is the pitch of your leadscrew?

What number(s) did you hit on your chasing dial?

My suggestion is to get a 1" - 8 nut from the hardware store. Set up and thread a 1 inch bar 8 threads. Set your compound to 29 and a half degrees off the face of the chuck. Be very diligent about getting the cross slide back to your zero every time.

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[darkzero]

This is what I was getting before, same tool, same everything, different advance.
It's like its not threading, but wiping the threads off a little more with each pass.

Sent from my SM-S320VL using Tapatalk

This sounds like you were not set to 29deg for threading which must be 29deg off the X axis when using the compound.

Do you have an Asian import lathe? Most hobby size Asian import lathes smaller than 14x do not have a full protractor scale for the compound slide. On lathes like this if you set it 29deg on the scale, it is 29deg off the Z axis and will cause the thread issues you described when trying to thread using the compound slide.

Take a look at the photos I posted in post # 4 here: http://www.hobby-machinist.com/threads/pm-1236-tool-post-issues.28428/#post-248506

 

[Tozguy]

I have had the same result with the compound set at 30 or so but feeding in with the compound is ok. now I am wondering if I should measure the angle and be sure it is actualy between 29 and 30

The 29.5 deg setting is recommended to allow for some potential error in the protractor on the lathe, since it is OK to be under 30 deg but never over. I think that it is a good idea to check the accuracy of your protractor for your own edification.

Also, if your protractor is set up like the one shown in the link that darkzero provided, I recommend that you establish a second index mark on the side of the cross slide. Set your compound at exactly 90 deg to the spindle axis and then scribe a mark on the cross slide opposite the 0 on the lathe's protractor. That way you will have a better time using the protractor for threading.

 

[ddickey]

Arn't you supposed to feed in with the cross slide the final couple thou? This is what I learned on Tom's Techniques site.

 

[Tozguy]

There are so many different threading jobs that I prefer to use the technique or combination of them that best suits the job and equipment as opposed to having the same hard and fast rules to follow for everything.