Improving single point thread quality?

LVLAaron said:
I'll be working up against a shoulder... so naturally I'm nervous about crashing the machine or wrecking a 400 dollar part. I did some testing with the spindle in reverse and using an internal threading insert on the outside of the part.

Will play around with it tomorrow when the bourbon wears off.
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I would be getting a lot of practice before I tried to thread a $400 part.
 
MrWhoopee said:
I was going to point this out, but we all know how intimidating threading is in the beginning, even at low speeds. HSS would probably a better choice for learning to thread. With the angle corrected, things should be better.
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First one needs to work out the basic timing for threading - just getting used to it. After a while, he can speed it up. It is good to practice on higher TPI at first as well. 4 TPI at normal speeds is terrifying to a beginner!
 
MrWhoopee said:
HSS would probably a better choice for learning to thread. With the angle corrected, things should be better.
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Working on choosing and getting a grinder/tool to sharpen HSS and carbide. I know it would be easier, but I can't make the tools at the moment.
 
jwmay said:
So its 59.5 on this compound? Why even say 29.5, if the witness mark is nowhere near that indication? I'm not scolding the OP by the way. I'm just trying to blame someone else for my SEVEN YEAR RUN of never successfully cutting threads...
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Its kind of silly. For some reason the Asian manufacturers of machine tools seem to have selected a different 'reference' for a lot of things, in this case, what the 'compound' angle is. On non-asian machines, "0" degrees is perpendicular to the material, on Asian machines it seems they choose 90 to be perpendicular.

MrWhoopee said:
I was going to point this out, but we all know how intimidating threading is in the beginning, even at low speeds. HSS would probably a better choice for learning to thread. With the angle corrected, things should be better.
Click to expand...

LVLAaron said:
Working on choosing and getting a grinder/tool to sharpen HSS and carbide. I know it would be easier, but I can't make the tools at the moment.
Click to expand...

I too would suggest HSS. What I find interesting, is carbide cuts really well at fast speeds, but does poorly when you get too low. HSS can't cut as fast, but seems to give a nearly as nice finish from really low RPM up to the max.

You CAN buy HSS insert tooling, which I hear good things about (@davidpbest can probably give you the best hints as our resident insert guy!), OR you can buy pre-ground HSS tooling that is pretty darn good, and probably just needs dressing every once in a while.
 
Couldn't go to bed and leave things hanging. After correcting the compound I took some cuts. Same material, same speed - Felt and sounded better, and most importantly, leaves an acceptable finish. No time for a super close up, but will take one in the morning for posterity.

Thank you everyone!


22-02-22 22-38-42 7073.jpg
 
Thread away from the chuck. Makes threading trivial. Checkout YouTube JoePi

Threading tool upside down in the holder; spindle in reverse. You can also leave the half nut engaged and jog the tool back into position.


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I’ve played with it. I mentioned earlier using an internal boring bar and the spindle in reverse. That way the tool forces aren’t lifting the carriage assembly, and I can see the tool. Makes me feel better.
 
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