PROBLEM WITH Z AXIS REZEROING BEFORE PROGRAM START

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06 Jun 2019 22:19 #136113 by SRcnc
Hello, I am pretty new to Linux cnc. I could of swore I posted this in the General section. I think someone may have moved it to gmoccapy. This is my first post on here. Thanks.

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06 Jun 2019 23:49 - 06 Jun 2019 23:50 #136133 by Hakan
Line N20 there is the problem.
Probably in combination with a HOME_OFFSET that does not allow Z0 in machine coordinates.
Last edit: 06 Jun 2019 23:50 by Hakan.

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07 Jun 2019 11:57 #136194 by SRcnc
Ah, I see it. The N20 G53 G0 Z0.

I guess I will go over to the fusion 360 forum and see what they have to say.

Thanks

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07 Jun 2019 17:37 #136237 by MaHa

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07 Jun 2019 18:01 #136240 by SRcnc
Yes, I will have to check homing. I asked over at the Fusion forums and they said that Fusion automatically inserts the G53 into the beginning of the program. You have to delete it in the G code or modify your post.

Still, though there definitely seems to be an issue with Z homing sequence. I'll have to look at my INIT file. Maybe instead of backing off the homing switch once the switch is triggered, it is trying to back off in the wrong direction.

I'll check when I get home.

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10 Jun 2019 16:46 #136491 by andypugh
I think that "homing" here is a red-herring.

The G53 G0 Z0 thing is intended as a safe retract so that the G-code starts from a known location.

What sounds to be happening here is that your G0 speed is too fast and the stepper is stalling.

I suggest editing the INI and changing the Z axis max velocity and acceleration to half the current value. If that fixes the problem then you can experiment with gradually raising the speed.

What you describe is _definitely_ a stepper stall.

Is it possible that the stepper supply voltage is lower now than it was when the machine was first commissioned?

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11 Jun 2019 09:39 #136577 by rodw
I'm with Andy and Todd on this. If you are going to loose steps on the Z axis, it will be on up travel when you are fighting against gravity. I've had exactly the same thing happening on the Z axis on my plasma machine whilst trying to maximise performance. On static tests it would be fine, but on the real word, it faulted.

i think it would be easily fixed if you edited your in file to reduce the joint velocity and accelleration. But I would also be checking to make sure there is no binding of the axis.

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11 Jun 2019 19:00 #136636 by SRcnc
Hey guys thanks for pointing me in the right direction. I definitely agree that my G0 speed is too high. I will definitely try editing the INI and changing the Z axis max velocity and acceleration to half the current value per Andy's recommendation.

Rodw, do you think that adding a counterbalance system to my Z-axis would help my situation? I do not think there is any binding of the axis but I will check thoroughly.

Thanks

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13 Jun 2019 22:47 #136853 by SRcnc
So when I try to edit my INI file it seems to not have any effect on the machine. For example I went to change my Z-axis max velocity and acceleration to half of their values and the machine still stalls at the top of Z-axis homing. I am saving before I close the INI file. So to test if my changes were being taken into account I changed starting jog speed to 30IPM so I went into the INI and typed 0.5 in the DISPLAY / DEFAULT_LINEAR_VELOCITY section and nothing changed. When I open GMOCCAPY the jog speed is default to 6IMP. Anyone know what I'm doing wrong?

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13 Jun 2019 23:27 #136855 by SRcnc
Well I think I have solved the stepper stall issue. I restarted my machine and and this time it took. I changed the HOME_SEARCH_VEL = 0.166 and changed HOME_LATCH_VEL= 0.083. Seems to not have the crashing issue any more. I will do some more testing just to make sure.

However I still can not get the start up jog speed to 30 ipm.

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