Back again with unexpected issues.

jtcrowder49 · November 14, 2021, 9:44pm

Hi All,

I am sorry to say I am back again, but you guys are so helpful, I can’t help but ask.

I was cutting a profile today from some MDF as a test piece.

I’ll spare the long detail but in todays work I noticed repeat unexpected issues and I wanted to reach out.

First: as you can see from the attached photos, I have inconsistencies in the DOC for objects on the same layer. I have triple check my machine and cannot find anything loose, broken, or damaged. DOC should have been 6.35mm. Material is measuring 6.50mm. You can see from the photo that the spoil board was eat up a bit for similar cuts on the same layer. Z DOC is off…the pocket cut should have been 1.6mm and is measuring almost 4.00mm.

Second: I cant help but think this issue is related to the first. The pocket operation has left vertical parts on this work and my last job. The function appears to preview as expected in simulation, but never clears out the bulk in the center of the spiral.

Third: All Y dimensions are shorter than drawn by about 2mm. All X dimensions are within 0.1mm at maximum compared to the drawing. I was not having this issue previously over the last year but I did modify my post processor about 2 months ago I think… Circles and arcs have been working fine since but I have only cut a handful of jobs since modification. I do not think this caused my current issue.

If I remember correctly GRBL has issues with circles. What post processor are you using?
In SheetCam go to Options->machine->post processor and click on the ‘edit post’ button. Add this as the first line:
post.SetOptions(post.ARC_SEGMENTS)
This will break circles into multiple arcs.

I will also add that my machine has not changed mechanically, firmware, or software.

If you could be so kind, please tell me if I am programming incorrectly, or I have some other underlying issue.

Thank you.

Charge Deck.DXF (95.9 KB)
Charge Deck.job (101 KB)

jtcrowder49 · November 14, 2021, 9:54pm

Here is the post processor I am using,
GRBL mill-router no toolchange Drilling corrected.scpost (2.9 KB)

Les_Newell · November 16, 2021, 12:05pm

Take a look at the G-code. Do the Z values look right? I so the issue must be with your machine. I’d suspect a mechanical issue such as a worn coupling or something sticking.

jtcrowder49 · November 26, 2021, 11:42pm

Sorry for the late reply. It takes me some time to work through things.

I checked every aspect of my machine and could not find anything loose or worn.

I went over all of it anyway. I am not sure what the issue was but I had been needing a reason to change the software I use to control the machine and feed the G code.

I changed the software and I ran a similar file again and had no issues cutting into my waste board.

Apologies for placing any distrust on sheetcam but in reality I was almost sure it was my ability to tell the machine what I want.

For future readers of this thread I went from an OCT2020 build of UGS to the most recent build of GSender (most recent at the time of this post)

Additionally, I reduced my spiral pocket stepover from 55% to 40% and it worked as expected.