Thread Cutting on the Lathe, Part Two - Grinding the Tool

[TomG]

This episode applies concepts covered in the first video to grinding a tool.

Tom

[b4dyc]

Excellent stuff!
Thanks for these videos

[TomG]

Thanks Andy, hopefully they help out.

Although you are no doubt waiting for the metric version.

Tom

[f350ca]

Great video Tom. You've inspired me to pay attention to the clearance angles and flat , rather than my usual that looks good enough. With a calibrated eye ball of course.

[TomG]

Thanks Greg.

Clearance angles on a V thread normally are good enough, but the flat requires close attention.

Tom

[DaveH]

That was very nicely shown - excellent video

DaveH

[PixMan]

Tom,

I SO much prefer your videos over the BoobleCain ones. I find that guy to be so annoying, and often WRONG.

Now a question: A 1/32" flat on the tip of the tool would be for a 4 TPI thread. Is that what you are making for a thread with that tool?

The formula for the flat at the root of an ANSI "UN" thread is .125 x P, or at least that what I've always used.

Here's an online calculator which seems to use a tolerance on that root flat of external threads, showing .1875 x P to (my recommendation of) .125 x P.

http://theoreticalmachinist.com/Threads_...erial.aspx

[TomG]

Hey Ken,

The flat should have been 1/8 pitch not 1/4 pitch. I thought it looked a bit large when I made the tool. Now how to edit the video...

Thanks for catching the error.

Tom

[TomG]

The new video is up and as an added bonus it's now available in HD. The mistake is corrected, now if I could just do something about the narrator.

Tom

[dallen]

why is it that the inserts that I have, have no flat on the point.

DA