Job will only burn correctly when centered 200,200, it seems

I have a few jobs that I have run at the very center of the field: 200,200. When I run those jobs, everything seems to burn fine. But when I create and save a new burn file that is not centered at 200,200, it does not burn correctly. For instance, I’m burning vector images, so I have four cuts: Red, Blue, Black, and Green. I’m burning a smaller object (Key Fob) and since I’m using Air Assist I want to use a larger plank of wood (11-12 inches long). When I create a new job of similar layout/sizing and move it over to the side (70,200) the job always has one cut that doesn’t align with the others, and it’s not always the same cut.

For example, the first time the Blue was off a couple millimeters. Started over, and the next time the Red was off a couple millimeters. I have stopped the job. Closed Lightburn. Shut down my LM2-Pro. Opened Lightburn. Opened the file. Turned on the Laser. Homed the job twice. Sent the laser to the center position (of the object, which was 70,200) and still one of the cuts is off. So I move the job to the very center (200,200), save it, close it, open it. Home the laser, send it to the new center (200,200) and voila! The job runs perfect. It has done this on separate jobs, separate days, and just seems weird. I would attach a graphic to show how it kept messing up, but I can’t attach anything.

I know, this has never happened to anyone, it’s only me. I’m the infamous “that’s never happened before” dude. lol

Check your belt tension and make sure it’s snug. You could be skipping a belt tooth when near one side or the other, because of a little extra slack, maybe?

  1. It’s simple to check
  2. The laser head could act as a tension point, meaning if the head was close to the drive side, it’d be less likely to skip
  3. It’s the single most common user error when assembling machines

It would actually help if you showed a picture of the job. “One of the four cuts” doesn’t tell us anything about what those cuts look like. If they’re just circles, they’re more likely to run cleanly than if they’re full of sharp corners, for example. Speed is also a factor, as are your acceleration and idle speed settings (those affect the motion when jumping between cuts, and how fast the laser tries to corner).

I get the skepticism but not sure where you’re going with this line of reasoning. The issue is almost certainly mechanical. Belts are a common cause of similar issues. Your particulars are peculiar and would benefit from more data.

  1. I’m assuming the preview looks correct but can you confirm?
  2. Have you tried running jobs in laserGRBL? Do you get the same behavior in the same extremities of the bed? This would rule out any g-code generation issue which I think is unlikely anyway.

Some other things I would suggest looking for:

  1. Check along the entire length of the belts. Are there any broken, missing, or disfigured teeth? They may only be engaged at certain positions.
  2. Have you checked the pinion/pulley on the stepper motors for any slipping? Check grub screws.
  3. Check that the pinion position is planar with all belt tension points. It’s possible that if these are not planar that belt tension is lesser away from the center of the bed.
  4. Similarly, look for any irregularities along the frame components that might be causing a shift in tension at the extremities. Particularly look for a bent or warped frame component. Also check for square.

Could one or both steppers be getting too hot?
They normally run warm to hot but if you get them too hot they can loose steps causing the pattern to shift.

Other thing to see if you can isolate is if you’re getting this behavior only in specific areas of the workspace. You mentioned 70,200 as causing problem. You may want to divide the workspace into squares to see which areas are showing the problem. This could provide a hint as to where to focus.

@MascotGraphics - I’m curious - why did you delete all your replies?

It seemed to confuse the matter when I tried to explain it.

What ended up being the solution?

There isn’t a solution. I can repeat this condition at will. I simply cannot run any job at all unless the job center is x200,y200. If that’s how it’s supposed to work, then my bad - I didn’t know and nobody told me I had to center every job at the middle of x,y.

Thanks but I’m just going to bow out, it’s not worth the headache… this is supposed to be fun.
Be well, Merry Christmas.

Okay. Was confused and intrigued because you marked this as solved but with deleted content.

Anyway, enjoy the holiday and circle back if you end up revisiting this.

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