I am trying to do a circular tool path in the XZ plane but I think I may have a bug in my MacH3 I have version 1.84.001. I know it is old but it has been working fine for me up to this point. I have a vertical mill that I use in a pinch as a vertical lathe. I want to cut a spherical radius on the end of a shaft. Lets say the shaft is 1" dia and the stationary cutting tool moves in the x axis. Positive X direction of the tool will move it into shaft. When Y = 0 the cutting edge of the tool is on the center line of the shaft. When X =0 the tool is just touching the outside diameter and when Z= 0 the tool is at the bottom end of the shaft.
So lets say I have the following g-code:
G0 X0 Y0 Z0
G18 ( TO SET THE XZ PLANE)
G0 X-.1 (FOR CLEARANCE)
G0 Z-.5 (MOVE SHAFT DOWN TO START OF CUT POSITION)
G1 X0 F5 (BRING CUTTER IN CONTACT WITH SHAFT)
G3 X.5 Z0 R.5 (THIS SHOULD GO THROUGH 1/4 OF AN ARC AND CUT A SPHERICAL RADIUS ON END OF THE SHAFT.)
However, what happens is if you had a piece of paper on the stopped spindle and a pencil in place of a cutter it would scribe two complete circles 1" in diameter. The X axis goes in and out twice while the z axis goes up and down twice and then finishes up were you would expect at X.5, Z0.
If I change the code to do the same thing in the X and Y plane and substitute Y for Z it works correctly.
G0 X0 Y0 Z0
G17
G0 X-.1
G0 Y-.5
G1 X0 F5
G3 X.5 Y0 R.5 (This goes through 1/4 arc with a radius of .5")
Thank you
Lou Cetrangelo
Saint James, NY