forum.cncdrive.com

It would nice if the Home function could have a function where once the limit switch had triggered and the motion had stopped, the cutter head would move back until the limit switches had just cleared. At that point the backoff function could back cutter head off further if the operator desired. So it would be (Home - limit switch encountered - stop - backup - limit switch cleared - stop).

Cheers
Gary Steele

That IS how it works now.

Yes, the backoff function does exactly how you described, it already works like this in the UCCNC.

On my machine I have to
set the back off function to a value which will be clear of the limit switch. If I then up the homing feed rate the back off function will no longer clear the limit switch, so i must enter a larger value in the back off function. My machine does not automatically move back to clear the limit switch. I have version 1.2111.

Post your settings.
The procedure that UCCNC does is as follows.
1) Move towards the switch using "Homing speed up" speed, until switch is triggered.
2) Move off the switch using "Homing speed down", until the switch opens.
3) Move away from the switch the "homing back off" distance.

If you have noise, or switch bounce, steps 1 & 2 can occur nearly simultaneously, resulting in the machine not backing off the switch.

Thanks for setting that straight. Now that that's straight. It highlights a problem that I will have to bring up with support. I have two circuits for the homing sequence, one handles the X,Y,Z axis. The other handles the A axis which is a slave to Y. The A axis circuit works as it is supposed to. The X,Y,Z axis does not, it stops when encountering the switch but does not retract to clear the switch no matter how I set the debounce. I guess that is why I felt had to use the back off to clear the switch. I will have to check to make sure my wiring is correct then bring it up on support. Thanks again.

Solved my problem I had the settings set for normally open switches when they are normal closed! Thanks again for the help.