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Z-Axis Home Problems
« on: May 28, 2014, 12:06:26 AM »
Hello,

I am setting up a new build and am having trouble with Homing the Z-Axis.

I am using 1 pair of limit switches per axis (X, Y, Z), with the two switches wired in parallel. I also use these limit switches for homing all my axes. The X and Y axes home just fine, exactly like you would expect, however the Z axis will not home. As soon as I hit 'Ref All', The Z-Axis indicator will flash RED for about half a second and then show GREEN, for being homed. The other axes will then move through their homing cycle. I have checked that the Z-Axis limit switches aren't being tripped in the starting Z position and that they are being read by Mach3, as seen in the Diagnostics Screen. The Z-Axis Limit switch will also stop motion if it is triggered.

Any ideas why X and Y will home properly, but the Z-axis is being skipped over?

Thanks,
Chris
Re: Z-Axis Home Problems
« Reply #1 on: May 28, 2014, 01:17:37 AM »
Hello,
I'm new here. I too am having Z-Axis problems. I figured I'd post is this forum as opposed to starting a new one. Hopefully it will help the next person. My issue is that I can't figure  out how to position my bit. Meaning, when I want to go from a 1 inch thick board to a 2 inch thick board how do I change the settings so that it starts an stay above 2 inches and vice versa. I have a CNC 3020.

Thank you for your help
Re: Z-Axis Home Problems
« Reply #2 on: May 28, 2014, 07:05:22 AM »
Hello,

 

Any ideas why X and Y will home properly, but the Z-axis is being skipped over?

Thanks,
Chris

Double check that the Z HOME is enabled and assigned correctly.

Russ
Re: Z-Axis Home Problems
« Reply #3 on: May 28, 2014, 09:40:19 AM »
Russ,

Yes I do have the Z-Axis homing assigned and enabled. Please see the attached pictures.

The same Z-Axis Limit switch I want to use for homing is also my limit switch, and it does work correctly for that function.

Offline 1Acnc

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Re: Z-Axis Home Problems
« Reply #4 on: May 28, 2014, 12:28:05 PM »
I think your pin number maybe incorrect. input pin can only be 10-13 and 15, the y is also wrong.
Re: Z-Axis Home Problems
« Reply #5 on: May 28, 2014, 01:03:45 PM »
I'm not using a parallel port for my IO, I'm using a USB Motion Card, the AKZ250, so there are more IO pins available. I do know that my limit switches are configured correctly, they activate correctly when looking at the Diagnostics screen and it works to stop machine motion when it is triggered.

Here is a link to my motion card.
http://www.automationtechnologiesinc.com/products-page/breakout-boards/3-axis-cnc-usb-card-mach3-200khz-breakout-board

Offline 1Acnc

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Re: Z-Axis Home Problems
« Reply #6 on: May 28, 2014, 01:52:12 PM »
To make sure I am reading your post corrector. The Z homes and reset  to 0 without hitting limit switch.( home in the incorrect position) That sound like you have noise on the Z switch wiring. To trouble shoot try moving the Z limit wires away from any other wires. You mite play around with the debounce controls in the General Config.
Re: Z-Axis Home Problems
« Reply #7 on: May 28, 2014, 03:35:18 PM »
Yes, that is correct. Both X and Y home just fine, but Z just takes its current position as home. Here is the sequence of events. I've attached screen shots

1) Start up (All axes show up as RED, so not referenced)
2) Click 'Ref All'. Z immediately shows GREEN and takes its current position as its machine coordinate
3) Y homes normally
4) X homes normally. This is where it finishes

The Z-axis never actually moves at all. It is just being skipped in the Homing sequence, as if the axis wasn't enabled. To me it seems like I have a setting somewhere that is telling Mach3 to only home X and Y, and skip Z.

I have checked the wiring and know that it is correct. The limit switch I use for homing works just fine as a normal limit switch. I've attached the Diagnostics screen (next post) showing all three limit switches in a triggered position. I manually moved the machine to get them all to go. One inconsistent thing is that all the M3 (Z-Axis) values are a larger font than the other 2 (X and Y). I have no idea if this means something or is just random.

Thanks for your help!
Re: Z-Axis Home Problems
« Reply #8 on: May 28, 2014, 03:36:48 PM »
Here is my diagnostic screen and settings screen.

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Re: Z-Axis Home Problems
« Reply #9 on: May 28, 2014, 05:57:39 PM »
I did not think you had a miss wire but some wire were induction ele noise into the Z lines but I was also thinking the system was zeroing the Z and I see that is not the case. So forget the noise idea.
I am at a lost.
Does the z ever move/run, jog or step?
Stepper or servo motors?
I would probably swap pin 1 and 2 in the Engine Config Port and Pins and then change in the Motor Home and Soft Limits, Home neg on Y and Z. To see if problem tracks.