Laser burn not lining up

Does anyone have a answer why a few burns are not lining up. I am using a YoraHome 6550 with a 15 watt laser a couple of times the laser seems to “jump” sideways. In one pic it shows a burn I did yesterday(the complete image) and one I was doing today. The other pic shows the same sideways jump on one I was doing today. I burned another one right after that and it came out good. I have made a lot of these coasters without any problems. The only thing good about this problem it does it at the start of the burn and not at the end! :stuck_out_tongue_winking_eye: :upside_down_face:



I suspect you have 2 or 3 things going on simultaneously:

  1. the areas of large skips is likely from belt slipping. Recheck all belt tension. Belts should be taught but with no slack but not stretched
  2. the fuzzy edges on the sides of your burns I suspect is caused by backlash due to the pinion on your X-axis motor being loose on the stepper shaft. Remove belt and see if you have any back and forth slip of the pinion against shaft. Retighten so that the grub screw is firmly secured to the flat portion of the shaft. There should be another grub screw at a different portion of the pinion. Secure that one as well. It’s possible you will have grub screws stacked on top of one another. In that case you will need to remove the top screw to secure the bottom one first. This could be the cause of the big gaps but only if secure slippage.
  3. You may also have an issue with scanning offset in addition to the backlash issue but suggest you first sort out any mechanical issues before pursuing this.
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Thank you berainlb! I will look into that in the morning. I was thinking it was about time to check the belts and screws. However, I had no idea what might be causing the fuzzy edges. I try and clean the laser lens everyday and never thought/knew it might be in the pinion. Thanks again Sir!!

I tightened up the x belt, had just a little slop in it. I adjust the pinion screws. The new burn look’s sharper but… The scanning offset was/is disabled.

Nice. Looks like removing the backlash has solved the fuzzy edges. Curious about the skip.

It’s apparent in both X and Y. If you’re certain that there’s no belt skipping it’s possible that your motor is losing steps. What speed are you running this job? Do you hear any whining or buzzing from the stepper motors?

If you reduce speeds does the issue go away?

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These are burned at 20 speed 75% power. This pic shows one that finished about an hour ago. Came out good with no skip. Just don’t understand the skip.

What units are you using?

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I am using 20 inches / min at 75% power. I am burning my 5th one and so far, knock on wood, no oops!!

Nice. Although 20 in / minute is fairly slow, especially for a large engraving. I would expect a machine with your design to be able to go 3x that without much fuss or skipping.

You may want to experiment with higher and higher speeds until you can cause a skip. Then back off from there.

Thanks, I’ll try that today. I will follow your advice until it skips or the color of the burn starts getting to light in color. Would be nice to go at a faster speed though.