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Author Topic: Re: Limit / Home Switches - how to adjust the overshoot?  (Read 2203 times)

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Re: Limit / Home Switches - how to adjust the overshoot?
« on: October 05, 2013, 07:00:08 PM »
Hi,
I have build my 2nd CNC machine using Mach3 and I really enjoy it.  I have a problem which I am not able to figure out

I have my home switches in place and also identified as zero switches.  I am nearly positive I have the inputs and homing configured properly since I have compared it to my other system.
I also share one normally closed input on line 10 configure as switch open to indicate a home position on all 3 axis.  This works as well.

My problem is that the system Homes First Z axis, then Y axis, then X axis.  When the Z axis homes it moves the home switch and stops.  Then the Y and Z axis home and when they get to their home switch they bounce off it about 0.05" or so.  I can't figure out how to adjust the Z axis to bounce off of the home switch when it is homing.  The reason I need this is about one out of two time I get a Reset due to "limit switch engaged." Then I have to reset the system or sometime shut it down to move the Z axis off of the switch.

Any Ideas how to correct my Z switch to make it bounce like the X and Y?  Also I replace the first Z switch with another and it still operates the same and I am about .250" away from the physical hard stop on the lead screw so nothing is in the way of the switch.

Thanks,
Durl

durlj@comcast.net

Offline ger21

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Re: Re: Limit / Home Switches - how to adjust the overshoot?
« Reply #1 on: October 05, 2013, 07:31:52 PM »
There is no adjustment for backing off the switches. Mach3 backs up  until the switch opens, and that's it.

There's a few things you can try.
If noise is causing the switch to trip, you can try using shielded cable. Or, Increase the Debounce setting in General Config.

You can also modify the homing script to actually move away from the switches after it homes.
Gerry

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Re: Limit / Home Switches - how to adjust the overshoot?
« Reply #2 on: October 05, 2013, 09:25:28 PM »
Perfect!  Thanks, setting the debounce to 500 fixed the problem!

Thanks,
Durl