Internal Threading

Please help....Using NCAM, does anyone know how to configure it to cut an internal thread on a lathe with the following setup up,

1) Spindle Rotation: Clockwise as viewed from the headstock.... M03
2) Cutter Position = 8, so the X-Axis would move from - to + to cut the thread.

I tried,

1) Switching the major and minor diameter but this gives an error message..The major must be larger than the minor.
2) A negative number for Initial thread depth but get an error message...Negative numbers are not allowed.

Also the AXIS graphic is not turning the cutter around to show it in position 8. Is there a way to do this?

Thank you in advance,

Barry

Hi
for this setup i woudt reconfugure the Machine 2nd setup to internal tread
this shoudt not be a problem if you got REF
so you switch the intire machine to the oposit

Look at the thread peak Param. You should also search the docs for G76 description.
Graphics prewiev needs tool type, front and back angle AND tool radius values to correctly show tool shape.

Perfect! Thank you so much! It all works great now and as expected, thanks to your help.

I found that the Thread Peak parameter (I) is used to select either Internal threading or External threading. Negative values are for internal threads and positive values are for external threads in NCAM. Interestingly, the document on http:linuxcnc.org/docs/html/gcode/g-code.html under the G76 Threading Section describes this oppositely..."Negative "I" values are external threads and Positive "I" values are internal threads." That's where I got confused. I'm guessing either the documentation is wrong or NCAM changes the sign (- to + or + to -) in the background.... this is not a problem though once you know how to use the sign.

As for the graphic in Axis showing an external cutter and not the selected internal cutter.... I was doing everything correctly by selecting an internal threading cutter from the tool table and the front and back angles were properly set, but it was still showing as an external cutter on the Axis graphic. However, after I ran the program in simulation mode 1 time, the cutter to flipped around on the graphic to properly show the internal cutter profile. I started a new file and tried it again and got the same result. It seemed a little unusual but again this is not an issue once you know this.

Have a great day, Barry

Barry wrote:

It all works great /quote]

can you tell us how did you overcome it
as some folks her might also Face this Problem