Thread Problems Part Failure

When I first learned to thread that would happen to me all the time.
Use the tailstock and a live center to support the end and hopefully all your troubles will go away---mine did. Plus you can move further away from the chuck.
I very seldom cut any threads that I don't support with the tailstock no matter what the size of the shaft is.
 
It sounds like your tool is above center.
 
Could use a die for at least that last .005". Or like said earlier, thats a small thread, just use a die for the whole thread.
 
I'll watch this thread with interest. I have to do almost the same job - a little stub of a 1/4" NC thread. I've done a fair bit of single point threading, and never really had much difficulty (except one job when I had to come right upto a shoulder and no end of thread groove allowed, so it needed to be ramped out - popped the end off the tool a couple times). Certainly the comments above are all good (especially the 29 degree). As Jocut shared, can you leave a pin out the end of the thread (just smaller than the minor diameter of the thread), support the outer end, then cut the pin off? Even just a bit of support will make a big difference. Also, what cutting fluid are you using? All fluids are not created equal (and everyone probably has their favourite).

As you get closer to being completed, repeat each pass at the same depth of cut (maybe even 3 times), until you get no more cutting at that depth (addresses spring in the set up).
 
I hesitate to use more than .001 or .002 on the final two or three threads. Yes, a live center will help, but .005 is a heavy cut on 1/4 20 threads.
 
Check your tool bit by using a black marker or layout dye and paint the cutting edges to see if the bit may be rubbing just enough to push the part instead of cutting. I know it is frustrating.
 
1. Top slide set to 29 1/2 degrees feeding with topslide (Not the issue)
2. I know I'm on center (Not the issue)
3. Used fishtale gauge to set up tool (Not the issue)
4. RPM is about 180 (Might be a problem)
5. Taking .005 cuts all the way through (Might be closer to the problem)
6. Cutting oil (Probably not the issue)
7. Supporting with tailstock (Have not done, but might help)

In short it might be the two issues of taking too heavy a cut at the end and slow rpms. I will try to do everything the same and change those two things and will report back!
 
Make your cuts no more than .003 and slow the speed to about 100 RPM. If necessary use a live center. Should solve the problem.

"Billy G"
 
Jocat54 do you center drill first or just ram the center into the part?

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