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Need Mach3/CNC help Please
« on: July 18, 2015, 01:42:47 PM »
A couple of weeks ago I lost the computer on my CNC machine. Since then I have replaced it with a Windows 7
32 bit computer with parallel port. Since I lost my files I had to reconfigure it, calibrate the motors,
and restore the tool table. All that done I ran some axis lop tests on all 3 axes, worked fine. I thought
I was good until:

I made a test pattern model and ran it through Bob Cam. THe pattern is simple, a 3.25 square cut .25 deep,
and a 3.00 Dia. circle .125 cut .125 deep on top of the square. Everything went fine for the square, but
when I cut the circle what I saw seemed like the center of the circle was incrementing to the -X for each
pass. The depth of cut was .025 per pass.

The first time I ran the code, the circle migrated about .25". Puzzled, I went to the Mach manual. Read
the section about motor tuning again. I cut the max speed and increased the acceleration time. THis helped,
the second time I ran the part, the migration was about 1/3 from the first. So I did it again. I cut the max
speed  to way below what I was using before the computer crash. Also increased the acceleration time. Ran the
code again and found the migration was a little worse. So it seems inconsistent, and with the new settings,
probably not motor tuning related.

In Windows I checked the CPU, disk, network, and memory usage while the motors were running, all seemed to be
very low, less than 10%, so I don't think windows is to blame, I was concerned about background processes
interfering with Mach 3. Probably not.

I am running out of ideas, can anyone help please?

maury
Re: Need Mach3/CNC help Please
« Reply #1 on: July 26, 2015, 04:06:35 AM »
Hi,
I'm no expert but have heard of a situation that can occur. The circular Gcodes G2 and G3 have two different operating modes. Read the Gcode description
included in the Mach screen. There is a setiing on the General Configuration page that determines which mode is set.
My setup is  'IJ set to inc'.
Hope it helps.

Craig
My wife left with my best friend...
     and I miss him!
Re: Need Mach3/CNC help Please
« Reply #2 on: July 26, 2015, 04:13:39 AM »
Hi again,
see the description of G90.1  It might be as simple as manually executing a G90.1 code then try running your code.

Craig
My wife left with my best friend...
     and I miss him!

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Re: Need Mach3/CNC help Please
« Reply #3 on: July 26, 2015, 07:27:40 AM »
check that your distance mode (absolute) and IJ mode (inc) are correct as Craig said and chuck your look ahead up to 100 it`s a faster computer yes its slowed from the pp but try it if it don't help put back down or up it`s something I found with putting a new computer on my router it was a bag of ********* to I increased look ahead to 250.

also check for backlash if you have a good DTI it will only take 5 mins