Re: [CAD_CAM_EDM_DRO] Cirular interpolation

Tony Dickson wrote:

> Folks,
> I'm having a heck of a time trying to get my milling machine thread a 4.500" hole with an 8 tpi thread in it. Can anyone tell me if Bobcad, Vectorcad or Dolphin can generate code for this particular operation. I think it might also be called helical interpolation, I'm not sure.
> I got in on the end of the "thread milling" post a while back, I hope I'm not repeating the same question.

I suspect you might be able to get Bobcad or one of the others to
do this, but you'd have to DRAW the thread, as 3 helixes, and
then lay a surface over the helix lines. This sounds like about
3 hours of work for EACH hole!

Try out my thread milling program at http://pico-systems.com/gcode.html
It generates the G-code by answering only a few questions, ie.
location, size of thread OD, size of thread mill, threads/inch and
depth of the thread, feed rate, and climb or conventional milling.
Note that for climb, it will thread the hole from the bottom to the top.

I got a 4-tooth single-row thread mill cutter in solid carbide for about $26.
This will cut any thread from about 40 TPI down to about 8 TPI.
(The upper TPI end is because the tip is truncated, the lower
limit is because of the height of the teeth and side clearance.)

Jon