Re: Servo as a Spindle - Mariss?

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "onecooltoolfool"
<joevicar3@i...> wrote:

> I want to use a DC brush servo as a spindle motor to give co-
> ordinated motion for tapping, but also have the motor run
> continuously fwd/rev. when machining as a regular spindle motor.

My 4hp spindle is a permanent magnet DC servo controlled by a +/- 10
volt using tach feedback. I have an encoder and the Rutex step
direction servo amp driver that I am going to install. MachX can
easily drive this as a spindle at precise speed using the S&D
spindle output.

> I'm thinking it would be fairly easy to have a circuit that
> would "engage" the G320 servo drive for tapping and then switch

over

> to direct DC or a PWM to act as a regular spindle motor. Aside

from

> the ERR/Reset pause when "engaging" the servo drive, any problems
> with doing this?
>

In my situation the spindle will always be driven by S&D. What I
imagine (don't know) could be done is to fire a relay that would
change the S&D drive source from the spindle to an unused axis like
C. Then, if you could calculate it, you could do hard tapping with a
coordinated Z/C move.

In my case the Gecko (or stepper driver) wouldn't know anything
changed. It would just see some momentary noise on the S&D lines
when the relay swicthes and possibly loose rotational position (not
that I care). I think the key is to always use S&D, just somehow
magicaly change the source.

Roger S