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Author Topic: Mach startup values are not consistant and "run from here" not working.  (Read 3253 times)

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I've been running several simple parts on my home built cnc router and have had good luck for the most part. Parts that I ran were great, considering this is a all wood and local hardware design.

I decided to be bold and started a project that was a two sided flip part and it took a long time to cut. I stopped the program and noted what line I was in, all positions and wrote these down so I could
restart the next night. Upon exit it asked to save fixture setup and I said ok.

When I restarted the next evening, all the position values came up as I left it. I loaded the same program and selected the line that I left off at, and selected Run from here. All this worked just fine.

I had another project and tried the same steps and Mach starts up with strange position values. I entered the last positions manually and restarted again at a line I left off. The program
ran just fine from there.

Now the third test was the heart break. I was working on a project with a nice piece of walnut and it was looking good. I had to shut down again and went to restart the next night. Again the positions came up in some weird values way off from where I left it. I again entered values in manually and went to restart from a line like 270192, and selected run from here.
This time the program jumps to the start and then to a line like 190013, and then just gave an e-stop error.

I don't have an e-stop active and no other errors display. I tried this several times with the same bad luck. I was unable to get the program to rerun from the line selected.

Why would I get such inconsistent results. I use a flashcut cnc at work and have never had such erratic results.

Is there something I could look at that might explain this problem? This started off so positive and has now become a real concern.

Grateful for any clues.



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I have a similar problem, is the  the gcode in incremental G91 or absolute G90 coordinates?
Anytime you stop in mid program, shut off the machine and pc then expect to resume from where you left off at a later time is asking for problems IMHO. In theory it should work but I know from experience the "Run from here" command is not always 100% reliable even under normal conditions. Its best to plan the job where you have the time to see it through to completion. Maybe one of these years Mach 4 will be released and all the quirks in Mach 3 will be fixed.  ??? 
We'll it's been a long time since I posted this question. Seems like it anyway. Learned a lot reading the forum and need to shout a thanks to you guys/gals that contribute.
 I'm running in absolute mode, but all these weird problems seem to have gone away.

I still don't have a lot of luck with "run from here" so I just plan on this ahead of time and leave the machine on until a job is done.
I still don't understand why the start up positions values are all over the place. I just gave up on this and re-zero and go.

I'm very happy at this point and plan to help my daughter build her one now. She's got the bug now after seeing what mine will do.