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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?

Re: Need Mach3/CNC help Please
« Reply #1 on: July 26, 2015, 04:06:35 AM »
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.

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.

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

Offline dude1

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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