G0 X.5 Z0
G32
G1 Z5 F.1

This would give us a 10TPI thread.

But now I want the cutter to rotate 10 revs per rev of the workpiece. In 5 inches of threading we get 50 revs of the workpiece, hence 500 revs of the cutter, so we get something like

G0 X.5 Z0 A0
G32
G1 Z5 A500 F???

And that's the question - what's the feed per rev for the G1 command? Do we treat the A and Z axis units as if they are comparable Cartesian units and set the speed to sqrt(A*A + Z*Z) = sqrt(10 * 10 + .1 * .1) = 10.0005?
When the A distance is large compared to Z (imagine we want 500 revs/rev), do we just ignore the Z part of the computation because it's so far down in the noise?

--

I'm not sure I understand completely.  But I'm thinking the F value should still be 0.1 if the A axis is configured as a pure angular axis (Degrees with 0 radius). 

Normally with something like a simple G1 motion where linear and angular motions are combined (ie X and A) then the feedrate is determined by the linear axes only.  G32 should plan the motion in exactly the same manner as a G1 move if the Spindle is exactly at the assigned speed.  But when executed the motion will be adjusted (geared) to the actual Spindle Motion.

 

Imagine a lathe with a rotating tool. The axis of the rotating tool will be called A and the position is measured in degrees.
(I know this is contrived, but the actual machine is harder to describe/understand)

Z is the axis of rotation of the workpiece, +X is towards the operator.  Assume all distance units are inches

A typical threading operation would look something like

G0 X.5 Z0
G32
G1 Z5 F.1

This would give us a 10TPI thread.

But now I want the cutter to rotate 10 revs per rev of the workpiece. In 5 inches of threading we get 50 revs of the workpiece, hence 500 revs of the cutter, so we get something like

G0 X.5 Z0 A0
G32
G1 Z5 A500 F???

And that's the question - what's the feed per rev for the G1 command? Do we treat the A and Z axis units as if they are comparable Cartesian units and set the speed to sqrt(A*A + Z*Z) = sqrt(10 * 10 + .1 * .1) = 10.0005?
When the A distance is large compared to Z (imagine we want 500 revs/rev), do we just ignore the Z part of the computation because it's so far down in the noise?

--

>
> I'm not sure I understand completely. But I'm thinking the F value
> should still be 0.1 if the A axis is configured as a pure angular axis
> (Degrees with 0 radius).
>
> Normally with something like a simple G1 motion where linear and
> angular motions are combined (ie X and A) then the feedrate is
> determined by the linear axes only. G32 should plan the motion in
> exactly the same manner as a G1 move if the Spindle is exactly at the
> assigned speed. But when executed the motion will be adjusted
> (geared) to the actual Spindle Motion.
>

>
> Seems like your example code has a bug. 500 revs should be 180000
> degrees.

>
> Hopefully the motion is not limited by the speed and acceleration of
> the A axis. Is there any cutting going on while the axes are
> accelerating?