Threading PR problems

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ryankelley

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Nov 22, 2008
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So I order blanks from ExoticBlanks(thanks for the fast shipping) tap and die set from HF and decided to give it a shot. Turned a tenon 3/8" dia grabbed the die and started to "make some threads", that's as far as I got. I would get maybe a half turn on and the tenon would break off. Tried again got alittle further but ended up with chipped threads and then the tenon snapped off again. Can anyone helpme out with what I am doing wrong. I've read the posts about threading, mabe I am missing something. Just thought I'd ask the "pros".
 
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Your tenon may be to big in dia. What size threads are you trying to turn? Also use pam cooking spray for a lubricant when cutting threads. Gives less friction and less chipping.
 
As Gary said , use Pam Cooking spray as a lubricant and try turning the tenon just a little under size . Also if you are trying to hold the die by hand in the die holder you will have allot of problems getting true , straight threads , and allot of breakage . Get yourself a die holder from Little Machine shop . It has a MT2 taper and holds the die .
 
Thanks for the info; one question though, what is considered alittle under sized? .001-.005 or .005-.009? Also should I bevel the end of the tenon.
 
ryankelley said:
Thanks for the info; one question though, what is considered alittle under sized? .001-.005 or .005-.009? Also should I bevel the end of the tenon.
Click to expand...

Sorry to say but there is no set numbers for how much undersized . It is going to vary with the brittleness of the PR . It's one of those "experience" things . Some blanks just can't be threaded but most can . Beveling the tenon will help a little but more important is not to stress the blank as you get to the end of the thread . Most of the breakage I get is at the last couple of turns of the die when I'm trying to get right up to the body of the pen blank . Best bet is to stop just shy and turn the last little bit down to just under the size of the threads .
 
I put the blank int he chuck on my headstock. I put the die in the holder on my tailstock. I cut the threads. Then I swap to the jacobs chuck in the tailstock and drill the hole in steps.

As said, it works for me. What's the term, YMMV.:wink:

Yeah, I'm doing the same steps as George above.
 
One thing I always wanted to try on some of the more challenging-to-thread-plastics was to warm them slightly with a hair dryer or similar appliance just prior to threading. On my to do list, but if someone wants to try it and claim the idea - have at it. Just don't blame me when someone says you used my hair dryer for what?
 
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