Re: [CAD_CAM_EDM_DRO] PC Control of Motion

ballendo@... wrote:

> tan wrote,
>
> >3.5) Panic stop also kills current to stepper motors (hardwired).
>
> Stan,
>
> Keep in mind that killing the power to the motors (stepper or servo,
> unless braked) will allow a presently cutting tool to climb,claw and
> grab into whatever it can reach as the spindle(definitely hard-wired
> to the estop) is winding down. Rack and pinion drive and Ballscrews
> allow this to happen the most, followed by high lead leadscrews. Be
> careful and THINK about what will happen when things are going badly,
> You may not want to kill those motors until the spindle has stopped!

This is a serious consideration. However, placing an energy dump
resistor
such that it shorts out servo motors (a little harder to do this with
steppers,
but not out of the question) will at least offer some serious drag to
the above
condition. Electrically released brakes that 'fail safe' into a braking
condition
would be the best. I was more concerned with a runaway servo axis as a
reason to hit estop, and use the pause or stop program keys when
something
was going wrong under normal programmed operation.

Jon