Hi,
I have a question, I am having a problem with parts not cutting out to size with cnc plasma. I was wondering if Sheetcam posts the code in Incremental or Absolute. Mach3 is set to Absolute, and I notice in the posted code that there is a G91.1, not sure? Just a thought as to what my problem is. Thanks for any HELP!!!
SheetCam uses absolute coordinates with incremental arc centres. The G91.1 tells Mach it’s using inc arc centres, overriding any of Mach’s configuration settings.
How far out are your parts?
I have a 6x6 square, it cuts 5 5/8 x 5 5/8. I also have 4" circle, it cuts 3 3/4 round. Perfect circle, perfect square but wrong size. If I change the incremental to absolute in Mach it comes out right. Wonder why if sheetcam codes in incremental arcs and mach3 is set to incremental and my drawing is set to incremental why are the parts not actual size? Thanks
I’m pretty sure this isn’t an absolute/incremental problem. If you use absolute code with a machine set to incremental or vice-versa the results bear little resemblance to the original shape. The code overrides Mach’s settings anyway.
This sounds like a scaling issue to me. Both of your examples are out by the same percentage.
5.625 / 6 = 0.9375
3.75 / 4 = 0.9375
Line the torch up with a tape measure then jog 10". Does the cutter move exactly 10"?
No, it moves 9 1/4 in both directions. I have tried everything to try and fix. I have recalibrated my axis in X & Y reset my steps per, etc. At a loss here, trying to figure this out.
Divide the distance it should move by the distance it actually moves. For example:
10 / 9.25 = 1.08108
Multiply your steps per unit by that value and try again. I would recommend doing this over nearly the whole travel of each axis rather than just 10" to get maximum accuracy. If you want to be really accurate try several tape measures. Tapes are not always that accurate!
How do I know my steps per unit? Once I do this, then what? Thanks
In Mach3 go to Config->motor tuning. The number you need to change is ‘steps per’. Remember to click on ‘save axis settings’ before selecting a different axis or clicking OK.
Les,
I have done this. I calibrated each axis and saved settings. What number are you telling me to put in? I have MDI 10" for both axis, it moved 9 3/4" in both directions and I put that number in, and saved settings but still not right.
If you ask for 10" and it moves 9.75" then your correction factor would be:
10 / 9.75 = 1.02564
Take whatever value you have in ‘steps per’ and multiply it by this correction factor. As I mentioned before remember to click on ‘save axis settings’ before selecting a different axis or clicking OK.