Re: [CAD_CAM_EDM_DRO]doodling with ideas

Giddings & Lewis Nemerimites and Pratt & Whitney Tape-O-Matics both used a
stepper motor and a belt to an ac motor at the en' of a ball screw with an
encoder at the other end. The larger motor and 4 pitch lead screw with a
shorted stepper motor for braking requires a much thicker and more
expensive stepper motor on the g&l. The P&W just uses electric brakes and
an ordinary stepper, Both are Slo-Syn

Clutching in a stepper when it is needed means you lose the index point,
because both machines must be interlaced, ie; the stepper detent
(Electrical) and the encoder null point must coincide. Do you want to
clutch in the encode and stepper together, or do you want to keep the
encopder tied to the axis translating mechanism?

Ted



At 05:32 PM 10/16/00 -0000, you wrote:

>Jon,
>
>I've been thinking along those same lines. But, instead of removing
>the main drive belt and attaching the stepper's belt, how about an
>electric clutched timimg belt pulley so both belts are always
>engaged. When you wanted the stepper action shut off the main
>spindle motor, activate the clutch and let the stepper do what ever
>spindle rotations are needed. Then everything could happen under the
>CNC's program control. Or maybe both belts could be always engaged
>without the clutch. Then the stepper would be constantly rotated by
>the spindle, wonder if that would be a problem having a stepper
>constantly rotating (with it's driver turned off, of course).
>