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How to make a internal/external threading tool on your lathe

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fatal-exception:
Dean, thanks for the comments!

I realize that leaving the tool full hard is not conventional, and possibly I should have put in the tempering part even if I don't necessarily follow that concept. All I can go by is experience, and even in tough steels, I haven't had a problem with the tool. I've been very impressed with how well wearing the tips have been. One of the most demanding threading applications that I used the tool for was to cut threads in ACME rod that were just below the root of the ACME thread itself. It wasn't even through the case hardening of the screws, but I did 5 of them and they all came out OK.

Andy, in my example, I DID cut below the centerline of the tool. This is the way I've always made them. There's obviously room for experimentation here, but my rationing is that this gives relief on the tip of the tool. Maybe it could be milled exactly to the centerline...I will try one next week and post the results. And your right about the angle changing, but for the 30 thou that I show to go under the centerline, it is negligible (wish I had the drawing here, I could quantify that statement). Soldiworks still rounded it off to 60 degrees on the drawing. I guess I should check the The Machinery Handbook to see what is acceptable as far as the point not being exactly 60 degrees.

Anyways, I'm off dune buggying for the next 4 days. I just got a GoProHD vid camera so I can get some premium on board footage....Catch you guys next week.  :beer:

Dean W:

--- Quote from: andyf on August 25, 2010, 07:20:02 PM ---
 I reckon Paul got it right by milling down to its centre-line. Anything above or below would reduce the tip angle,
Andy

--- End quote ---

Andy, what I said was,  Paul didn't mill to centerline, not that he did!  He milled to under C/L.
He confirms this in his most recent post.
If it works well as it is, it's probably just perfect. 
I've made a cutter or two, and on ones similar to this, usually putting the cutting edge right on centerline, or very close,
does just what it's expected to do, as long as the radius of the cutter provides clearance directly beneath the cutting
edge.

All said, I hope I made it clear that I think the tool is a great idea!

Dean

DeereGuy:
Yep, I think it is a good idea also...and will try it myself when I get a chance. :thumbup:

fatal-exception:
Hey guys, I'm back and in one piece. Good weekend for total km's, 300 +/- a few. Sore now, but feel good about the buggy. It has 1600km saying it's reliable....other than brakes...

Heres a shot taken today, after the storm...

Pete.:

--- Quote from: andyf on August 25, 2010, 07:20:02 PM --- I suppose too much resharpening by stoning down the flat top would eventually reduce the angle by an unacceptable amount.

--- End quote ---

You could avoid this by always stoning the tip whilst changing the angle radially, so that the flat top always radiated from the same point just on or below CL.

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