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Author Topic: program skipping commands (not steps)  (Read 1987 times)

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program skipping commands (not steps)
« on: March 27, 2015, 11:07:22 PM »
I was running a fairly simple program today and the machine appears to have skipped over two G1 commands. The reason I say skipped commands instead of skipped steps is that when I checked the machine location after the program ran, it was off by exactly .5" in X. The program was taking .25" steps in X, so this would be consistent with skipping over two G1 commands. This has happened once or twice before in the past couple of months. It is not repeatable, and it is not an error in the program, since I can run the program again and get a correct cut (as well as run it in OpenSCAM and get a correct visualization).

Any thoughts on how to prevent this in the future, or at least confirm this is the problem?

I'm running Mach3 on a Core 2 Duo Windows 7 machine, talking to the router via a USB controller board.

Offline ger21

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Re: program skipping commands (not steps)
« Reply #1 on: March 28, 2015, 08:12:04 AM »
It's most likely a case of your steppers losing steps which is causing the lost position. Try reducing your acceleration and velocity in motor tuning by about 20%.
Gerry

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Re: program skipping commands (not steps)
« Reply #2 on: March 28, 2015, 10:56:27 AM »
ger21 wrote:
Quote
It's most likely a case of your steppers losing steps which is causing the lost position. Try reducing your acceleration and velocity in motor tuning by about 20%.

It seems a rather remarkable coincident that both the x and y axes would skip a number of steps exactly equal to those commanded in the G1 command.
In addition, the program consists of the same sequence of moves being made repeatedly, just shifted in Y, but never again are steps missed.

Offline ger21

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Re: program skipping commands (not steps)
« Reply #3 on: March 28, 2015, 11:02:30 AM »
What USB controller are you using?

Mach3 has never been known to "skip commands".
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html
Re: program skipping commands (not steps)
« Reply #4 on: March 28, 2015, 11:25:46 AM »
It's an AKZ250 supplied by JCut on a 6090A router.

Offline Tweakie.CNC

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Re: program skipping commands (not steps)
« Reply #5 on: March 28, 2015, 11:55:57 AM »
Just out of curiosity, is your Gcode program longer than 500 lines of code ??

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: program skipping commands (not steps)
« Reply #6 on: March 28, 2015, 12:26:04 PM »
Code is 492 lines, containing no comments.
Error is occurring around line 7

Note that the error is NOT repeatable

Offline BR549

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Re: program skipping commands (not steps)
« Reply #7 on: March 29, 2015, 01:48:53 AM »
Try using another program to test. I have seen it when the Gcode file itself was corrupt and it would skip the corrupt part.  Remaking the program over from new would fix it.

Just a thought, (;-) TP