Helical interpolation- Mach 2 or Mach 3

[johnd]

Does mach2 or 3 support helical interpolation for boring a hole on a vertical mill? If so where can I get information on doing this and also possible examples of.
I need to bore a hole at 2.250" dia. by 4.000".
Can I get a similar finish as with a boring bar without the step down mark.
thank you

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[CitizenOfDreams]

Yes, Mach3 perfectly understands 3-dimensional arcs. Here is an example of a hole cut in spiral motion:

G0 X-11.5 Y0.0
G3 X-5.75 Y-9.9593 Z-0.1667 I11.5 J0.0
G3 X11.5 Y0.0 Z-0.5 I5.75 J9.9593
G3 X-5.75 Y9.9593 Z-0.8333 I-11.5 J0.0
G3 X-11.5 Y0.0 Z-1.0 I5.75 J-9.9593
G3 X-5.75 Y-9.9593 Z-1.1667 I11.5 J0.0
G3 X11.5 Y0.0 Z-1.5 I5.75 J9.9593
G3 X-5.75 Y9.9593 Z-1.8333 I-11.5 J0.0
G3 X-11.5 Y0.0 Z-2.0 I5.75 J-9.9593
G3 X-5.75 Y-9.9593 I11.5 J0.0
G3 X11.5 Y0.0 I5.75 J9.9593
G3 X-5.75 Y9.9593 I-11.5 J0.0
G3 X-11.5 Y0.0 I5.75 J-9.9593
G0 Z0.0

What CAM program are you using?

[dharmic]

Erm...

It understands simple helices with the circular component on one of the planes XY, YZ, XZ and an orthogonal straight component along which to stretch the helix - as per your example, CoD, with the circular component in XY and stretching out through -Z.

But try and do a general 3D arc with I, J and K components like my post tried to generate for a helical lead-in to a pocketing operation before I figured what options to switch off. You get a big fat "Nope" from Mach3 as soon as the curve leaves the current operating plane as selected by G17/18/19.

Academic only for this question though - per your example for a helical mill straight down through the Z axis it works fine. Do it as a series of G2 or G3 moves, keep them under 180º per move, and add a Z component to each move. It will run each arc and push in on Z proportionally throughout.

[CitizenOfDreams]

OK, I see the difference now. Fortunately, as you said, true 3D arcs are not needed for what the OP is trying to accomplish.

[dharmic]

I only jumped in because I remembered what a mongrel of a time I had getting it sorted out, don't want anyone else to ever have to go through that...

[ger21]

Do it as a series of G2 or G3 moves, keep them under 180º per move

It works fine with full 360° moves.

[dharmic]

My bad, I was thinking of 180º causing issues when using R instead of I,J.

[johnd]

Thank you all for the response. As far as program (cam) that I am using is Bobcad. After seeing the examples it seems
pretty straight forward.
Will probably be trying out after lunch.
Thank you.