Re: 4th Axis Concept (long)

--- In CAD_CAM_EDM_DRO@y..., datac@l... wrote:

> In the following explanation, picture in your minds 2 motors

driving a Sherline or similar Lathe spindle, First motor: a dis-
engagable stepper, The Other: A traditional spindle drive motor....

Chris,
Interesting idea. If I where to do this I would use a servo motor
instead of a stepper. A servo motor with encoder can be controlled
with a Gecko 340 using step and direction input just like a stepper.
When in lathe mode just switch out the controller and apply DC
directly to the servo. You could get the RPM you need without having
to clutch a motor in an out.

There is still the problem reseting the piece to zero. I think this
could be handled by turning off the power and rotating the shaft by
hand to a known position. A fixed position could be established by
resting an arm, attached at a right angle to the 4th axis shaft, on
the top of a 1-2-3 block or some such.

Roger