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Author Topic: Homing and Limits  (Read 2457 times)

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Offline kolias

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Re: Homing and Limits
« Reply #10 on: February 14, 2017, 11:40:14 AM »
As Dave mentioned I never had a problem to jog away from a limit. Are your limit switches wired NC or NO?
Nicolas

Offline Davek0974

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Re: Homing and Limits
« Reply #11 on: February 14, 2017, 01:26:57 PM »
Ah, I see - yes i had the same issue and just wound the screw off the stop by hand a few times. Once soft limits are set properly, the issue never occurs again, my soft limits are set 3mm off the hard limits IIRC.

You would think that as Mach knew which way the axis was moving when it hit the limit, it would simply allow movement in the opposite direction, but i Mach is what it is, end of.

What it is, is really a pretty good way of building CNC machinery, there are other options out there now but i have no idea if they are better, the same or worse than Mach3.
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives
Re: Homing and Limits
« Reply #12 on: February 15, 2017, 05:45:18 AM »
Hi Kolias, my limit switches are inductive proximity, two wire and ground the pin when tripped so they are effectively NO. I know this is not the safest option but the rebuild on this machine has been 'extensive' and expensive and as the sensor limit plates are welded in place (and the sensor adjusts) I decided to run with them. I can jog away from a soft limit as the 'reset' is not flashing but if you hit a hard limit (any of my 3 sensors) then machine stops and you CANNOT move ANY axis while Mach3 is in 'reset' or E-stop. Having the 'auto limit override' solves it to an extent but it would still have been nice to have the software detect which way the limit switch had been hit and know that it will now only allow jogging 'away' from that direction.

Not the end of the world..!
Pacer Cadet, guts gone, new stuff installed, sounds like a full string quartet in motion...

Offline Davek0974

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Re: Homing and Limits
« Reply #13 on: February 15, 2017, 06:26:04 AM »
Not sure what machine this is on but on my bridgeport mill, the hard limits are wired into the safety circuit NOT mach3, if it hits a hard limit it cuts all power to the axis drives so the ONLY way out is the reach for a spanner and screw the axis off by hand.

This was a safety setup decision - it has servo motors and in the event of a runaway drive it would smash the end off the machine in a flash so a very hard limit was thought safest.

The soft limits are the main operation limit system.
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives