Mach 3 DRO/Gcode doesn't match

[gbward4]

Hey guys. Sort of a noob to CNC, not so much to machining.

Here's the deal. I've got my CNC machine all set up, and I'm using Mach 3. I can go anywhere in my 98"x50" table within 0.003." I am certain that my backlash is compensated properly, I am not missing any steps, and that my steps per are dead on. In short, if I enter the MDI screen and give a "g0" instruction, the machine goes exactly where I expect it to, and the on-screen DRO and real-life measurements reflect that.

My problem arises when I am running G-code. My on-screen DRO (incidentally where the real life tool is) gets out of sync with the G-code instructions.

You can see from the screenshot below that I am stepping the G-Code with the "Single BLK" command and that Mach3 just received the "G1 9.6894" command, but my router actually moved to +9.7064, which is 17 thousanths out! This is verified by real life measurement.


Here are the links to my G-Code.
Part I'm discussing
Other Part I'm having trouble with

I'm not sure what I'm supposed to do here, the errors seem to be random anywhere up to 0.035". I have tried enabling/disabling backlash compensation (and restarting program like it says), it only makes things worse due to wiggly backlash.

The crazy thing is, if I stop the G-code, click "goto z" and then goto the MDI page, it now includes that stupid offset. For example "G0 y0.2" goes to +0.217, no matter what I "G0" it adds .017 to it and sends that to the DRO and the machine.

Please help a confused man.

Thanks
-GB Ward

[ger21]

What are your steps/unit set to?

[gbward4]

X Axis:
Steps Per: 1419.221006
Velocity: 469.68
Acceleration: 10.019581

Y Axis:
Steps Per: 1418.450557
Velocity: 469.44
Acceleration: 10.015506

Z Axis:
Steps Per: 8024.030299
Velocity: 30
Acceleration: 3

[ger21]

How old is that version of Mach3? Looks like 2.63 maybe?

I'd recommend a newer version first.

Another guess it's it's related to CV and backlash comp.

[gbward4]

Thanks. Upgrading appears to work.