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After homing axis don't back off Switches
« on: December 13, 2013, 09:41:24 PM »
I've never had much problem with my mini mill and Mach until now!

When I home the machine each axis does not back off of the limit switch and the DRO's don't go to zero. The problem just started today. I have checked and everything seems to be OK.

3 limits wired to 3 inputs. Using each switch as home and limit.

Does anyone know how I have turned this function off??

Thank you for any help you can give.

Bob Keyes

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Re: After homing axis don't back off Switches
« Reply #1 on: December 13, 2013, 10:04:05 PM »
hi
two things come to mind first i would confirm my homing switches are working, second i would go to the diagnostics screen there you can home axesses individually see if one or more will work. i think but cant look now that z homes first then y then x if you dont get z homed it will not continue to home the other axises so your problem will most likely rest with z. hope this helps if i have written any details wrong please correct
Re: After homing axis don't back off Switches
« Reply #2 on: December 13, 2013, 11:01:04 PM »
Thanks for your reply. However, as oft times happens with me, I was not clear enough. Z is first and it goes to the limit, but does not back off the switch. Then Y goes to the limit and does not back off the switch. Then X does the same. When X hits the switch. The reset come on with the tripped limit. Now, I have to back off each axis by overriding the limits or turn off power and do it manually. The problem is that it doesn't back off the switches.

Any other thoughts??

Thanks again for your reply.

Bob Keyes

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Re: After homing axis don't back off Switches
« Reply #3 on: December 14, 2013, 05:07:23 AM »
Do the LEDs at the side of the Z and Y DRO turn green?
Hood
Re: After homing axis don't back off Switches
« Reply #4 on: December 14, 2013, 07:06:17 AM »
Yes. The LED's do turn green.
I reloaded Mach3. No help.

Bob Keyes

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Re: After homing axis don't back off Switches
« Reply #5 on: December 14, 2013, 07:38:54 AM »
Your problem is the X axis home switch.
What is happening is Z moves to switch then backs off and Home is set, Y does the same but then X hits the switch and triggers an E-Stop.
You may not think Z and Y are backing off but the fact the LED goes green and there is no E-Stop called proves that they do.
The reason for the X causing the problem could be a bouncing switch contact, if your switch does not have a clean snap action then what happens is it is triggered then closes then opens etc etc and that causes Mach to first see it as a Home switch then as it reopens again Mach sees it as a limit.

So best course of action would be to probably see if you can get a better switch but as a test you could increase the Debounce Interval on General config page to maybe 2000 and see if that helps. If it does reduce as much as possible.

Hood
Re: After homing axis don't back off Switches
« Reply #6 on: December 14, 2013, 07:45:25 AM »
Hood,
Thanks. I'll check that out right away. But, why did it change from backing off a visible amount to nothing visible? Don't understand that????

Bob Keyes

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Re: After homing axis don't back off Switches
« Reply #7 on: December 14, 2013, 08:09:49 AM »
It shouldnt change unless you have altered your homing speed or your acceleration/velocity of your motors. However if the switches are becoming weaker in their snap action that could also cause the distance to change as they are not snapping open and again closing as cleanely as they once did.
Hood
Re: After homing axis don't back off Switches
« Reply #8 on: December 14, 2013, 01:17:31 PM »
The Mach 3 manual says you can set the homing up so that it does not back off the switches, but I can't find another reference on how to do it. It would seem that I have some how set that preference unintentionally. Does anyone know how to do this??

Bob Keyes

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Re: After homing axis don't back off Switches
« Reply #9 on: December 14, 2013, 01:40:15 PM »
You can not set up to back off the switches unless you write some VB and put it into the RefAll button.
The way Mach works is it moves to the switch, triggers it then reverses and when it closes Mach will stop the axis and set that position as Zero (or the value you have in Home Off)

Hood