A axis continues rotation ?

[thirty78]

Hi All,
I'm trying to cut a dome, I use wjbzones GcodeOut to get a gcode cross section (very nice program).
How do I write gcode to have a A axis continues rotation that is separat from the cross section generated by GcodeOut ?
Thankful for any help

/gunnars

[HuFlungDung]

Are you trying to cut the dome with a spiral cut based on a projected spiral, or circular cuts with small ZX or ZY shift between layers?

[thirty78]

My plan is to slow feed rate the XZ and adjust the A axis feed rate.
I thought that the easiest way to go for a beginner?

[HuFlungDung]

I don't think it will work.

While it is possible to change the arc plane from XY (G17) to XZ (G18) with a modal command, it would, in my experience, not be possible to command a simultaneous movement such as
G02 XZ IK A
which is what you would need for a smooth movement as I am visualizing that you are referring to. The feedrate on Z and X would be so excruciatingly slow, that the A axis would also be severely retarded in its movement of several thousand degrees of rotation.

I think you would be better off to interpolate your 2d curve into short segments (creating an XZ movement along the curve) and then insert a
G01 G91 A360.
between every segment of that interpolated curve.

Watch out for 'running out of distance' in your A axis, even with G91 active, the controller will still be keeping internal track of the G53 position of the A axis, and if you go higher than.....I dunno... 9999 degrees (a sample limit) , it may stop on you. You could go clockwise for one rotation, then CCW the next rotation, if you can settle for climb milling cuts alternating with conventional milling cuts. Use
G01 G91 A-360.
to rotate in the opposite direction.

You will need to decrement your feedrate in A as you work your way up the curve since the circumference is growing.

For machining in the horizontal A axis attitude, a lathe would be a better choice for productive machining rate.

[thirty78]

Thank You,
No magic sub-programs
I'm going to try it, its a lot off editing are there any text editors that I can use to put in a new line every other line?
Its actually a C axis + XZ that I work with.