Re: [CAD_CAM_EDM_DRO] latching E-stop button and relay vs. momentary E-stop button and latching relay

On my CNC Taig mill, my mechanical e-stop button (which mechanically
opens a NC switch until it is turned and reset) disconnects power to
the Xylotex stepper driver board and the large solid state relay that
controls the spindle. It does not (yet) send an E-stop signal back to
EMC2 to halt step and direction signals. I need to hook up a latching
relay to prevent power-on after a power outage.

Separately from my hardware estop, pressing F1 on the computer
keyboard sends an e-stop signal to EMC2. Since this is not yet wired
into the spindle relay, this acts as a sort of feed hold, stopping the
axis motion but not the spindle. I have glued a large red plastic
knob to the F1 key on my keyboard to make it easier to find this
button when things start going wrong. I can bring EMC2 out of this
condition by pressing F1 then F2, and it remembers the machine's
position, and you just have to restart the program from the beginning.
This is good when I realize I have goofed somehow (wrong tool or
length offset, messed up axis zeros, etc, but not deserving of a full
emergency stop.

Michael

On Sun, May 11, 2008 at 10:47 AM, Monte <montejw@...> wrote:
> Is this an either/or? I've seen diagrams showing both, does it make a
> difference which to use, other than it depends on the e-stop button
> you might have on hand?
>
> I bought an e-stop button some time ago (can't locate it right now),
> and I think it's a mechanically latching button. I wouldn't need to
> wire the relay as a latching relay would I? Or can it be wired as a
> latching relay for another layer of redundancy of sorts.
>
> For a small mill (Taig, 200 some oz steppers, 100 ipm rapids MAX,
> probably more like 50, 20 tpi leadscrews) would cutting the power
> supply to the stepper drivers and spindle be adequate? I don't have a
> BOB as yet, so I'll deal with lost position and all that with Mach.
>
> Monte
>
>