What to do in an estop ?!? was Re: safety

RayHex,

IMO, "losing place" is the least thing to worry about in an estop.

I worry about recommendations to just drop power in an estop! After
all, one REASON the estop MAY be warranted is that a hand or hair, or
similar may be caught in the machine, or trapped near a cutter. And
the cutting forces as the spindle "winds down" (with the drives de-
energised) will backdrive many types of machines. This could easily
make a "caution" situation into a "dangerous" one. (To use the osha
meanings of these two words)

Expensive machines will likely have axis brakes; but I'd hazard
a guess that most of our "homebuilts" don't... (pun intended)

Ballendo

P.S. I just re-posted Bill W's question to drive sellers about this.
I'd like to add to that message a request for ideas on how to
implement an overall estop solution, as that message was basically
about saving the drives (if possible). This matters to any of us who
biuld and/or use a cnc machine!

--- In CAD_CAM_EDM_DRO@y..., "Raymond Heckert" <jnr@a...> wrote:
> So, it follows that you only want to use that technique for E-Stop,
and not
> 'feed-hold', since you'll probably 'lose' your place if the motor
> 'un-winds' (talking about stepper motors, now)?
>
> RayHex
>
> ----------
> > From: JanRwl@A...
> > To: CAD_CAM_EDM_DRO@y...
> > Subject: Re: [CAD_CAM_EDM_DRO] Re: safety
> > Date: Monday, April 15, 2002 2:01 AM
> >
> > In a message dated 14-Apr-02 20:11:41 Central Daylight Time,
> > mariss92705@y... writes:
> >
> >
> > > Grounding the "disable" input causes all the MOSFETs
> > > to turn off, making the motor lines float. This means there is
no
> > > electrical connection to the motor wires while in "disable".
> > >
> > Thanks for the confirmation! Jan Rowland