Quote Originally Posted by Jonathan View Post
Another way is to make the E-stop switch interrupt the stepper motor step signals (resistor + switch to ground would do it, or better an AND gate on each), or use their enable input if they have one. That way the motors remain powered upon e-stop and make sure the axis' doesn't move. If you just cut the power to the stepper drivers then there's a very slight chance they may be damaged (but then it's an emergency after all, so that shouldn't matter?), but more importantly the motor could keep spinning for a bit due to it's inertia, or gravity with the Z-axis. I once had a power cut whilst my machine was cutting aluminium and it caused the cutter to plunge into the material and shatter - the Z-axis dropped due to gravity.

Having said that I've not bothered with any of this :whistling: ... but that's not reason for anyone else not to.
Yes this works ok for killing motion but it won't do much for you if the spindle grabs you. Plus interia will still move a powered stepper if going fast eneough.
If you want a truely safe EMERGENCY STOP then you kill power and that includes the spindle. . . It's not difficult or expensive just a few relays and some wire.
Lots of folks think because it's just Hobbie CNC then this level of safety hisn't required. . . this will be ok 99% of the time but it only takes 1% to chop your fingers off or crush your hand.!! Even the smaller steppers will crush your hand in the blink of an eye just as will the light duty trend/kress spindles slice your fingers off.! . . . His it worth the risk for £10-15 quid more.? Not to me it hisn't. . . .To use none at all is just plane stupid.!