Author Topic: Problems with calibrating Z axis  (Read 15103 times)

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Offline rockaukum

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Problems with calibrating Z axis
« on: January 31, 2017, 02:02:49 AM »
Hello,
New to this cnc stuff and do not fully understand this stuff and in need of assistance.  I ran a cut that was designed in Inkscape, converted with Sheetcam and run via Mach3.  The program cut where it was supposed to however when it was supposed to raise the Z axis, it did only partially or none at all.  I went to calibrate the motors.  First the X, it was off by 1.25" on a five inch test.  Did the calibration several more times and got it settled down.  Next was the Y axis.  It was spot on.  Lastly the Z axis.  I set it for two inches, the motor came alive at least in sound but did not move but 1/8".  I set the value and tried again.  The motor sounded but no movement.  I put mach3 back to the first screen and manually moved the Z with the page up / page down buttons.  Z moved without any issues at all.  So the question is...  What is going on?  Any help with this would be great!  I took a measurement of the cut and it was 3/16" deep with the code requesting 1/8".
If any additional information is needed to help with this, please ask and I'll do my best to get it.  Please keep in mind my limited knowledge but eager to learn.
Thanks much!
rockaukum

Offline Tweakie.CNC

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Re: Problems with calibrating Z axis
« Reply #1 on: January 31, 2017, 02:12:34 AM »
Initially, make sure you are setting-up Mach3 in the Units (Inch/mm) you intend to use (Config. / Set Native Units).

In Members documents there is a calculator for finding Steps per Unit and also a math's example.

http://www.machsupport.com/forum/index.php/topic,16315.0.html

http://www.machsupport.com/forum/index.php/topic,12512.0.html

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.

Offline rockaukum

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Re: Problems with calibrating Z axis
« Reply #2 on: January 31, 2017, 10:59:22 AM »
Tweakie.cnc,
Thanks for the reply.  I believe mine is set up in inches under the configure tab.  Makes even more sense as the X&Y are good to go or is there something else that could cause that? Once it is set it is for all axis, correct?  I'll do the calcs to get a starting point as well.
Thanks again,
rockaukum

Offline rockaukum

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Re: Problems with calibrating Z axis
« Reply #3 on: January 31, 2017, 01:29:24 PM »
So...
I confirm the machine is set for inches.  Good there.
Then for kicks, I go and do a calibration again.
X & Y are good as before.
Z however moves the full range without stopping whereas before it either moved a slight amount or none at all. I stop the process as i do not have limit switches, yet!
I did not build this machine so I do not know the details.  I am trying to establish the steps per inch for a starting point.  The motors are 425 oz. in., 1.8*/200 steps per rev.  (Automated Technologies inc. KL23H286-20-8B)   How do I determine if this is set up with any microstepping, and if it is, how do I determine what the value is?
Doing a lot of reading and finding a lot of information, just not what I need (I think I need)
Thanks,
rockaukum

Offline rockaukum

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Re: Problems with calibrating Z axis
« Reply #4 on: January 31, 2017, 02:38:32 PM »
UPDATE:
I got it figured out.  It must have been way off in the previous calibration as the Z kept going to the stops.  So I did the calibration again with the requested movement set at 1/8" instead of 2"  Hit okay and sat with my finger on the stop button.  It moved and stopped on its own.  Entered the measured movement and calibrated again.  After two more calibrations, i had repeatable results.  I'm happy with that however now the damn thing moves a pace slower than a snail.  I over rode the speed on the screen to complete the cut.  I got an abnormality error which states: List of Abnormalities, G90/G91 State.  Any suggestions on what that means?
Time for more reading to get the speed issues dialed in...
rockaukum

Offline Tweakie.CNC

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Re: Problems with calibrating Z axis
« Reply #5 on: February 01, 2017, 01:44:41 AM »
The G90/G91 relates to Absolute/Incremental movement and the appropriate method is usually specified within the Gcode file.

The Mach3 manual has more detail and can be downloaded from here http://www.machsupport.com/help-learning/product-manuals/

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.