Skewed Images When Engraving / Scanning . . . Please help?

I am a novice, so many apologies in advance if I breach a protocol or say something silly. I’m just hoping someone can give me a hand . . . it would be much appreciated.

When I am engraving (which I think is sometimes called “scanning”), the images end skewed and uneven. I have attached a photo below showing this with some text I was trying to engrave in a piece of MDF.

I have a 55-watt OMT Big Blue Chinese Laser, with a Ruida controller. I purchased it about two years ago, and I have never been able to do proper engraving. It cuts perfectly and I’ve just ignored the issue about engraving. But now I would like to do some engraving work, and it kinda breaks my heart that I can’t do it. (Example: engraving a piece of MDF with a photo of a brick wall for my model railroad . . . it works, but the image is wavy / skewed and unusable.)

Any assistance would be very helpful and much appreciated.

All my best,


This looks like something mechanical is lose… Have you gone over the belts, head and anything else that moves…?

Also check your grub screws that hold the pulley…

From your comment, has it always done this?

If so I’d expect the cut to follow a similar pattern…


Thank you, Jack. I will check the mechanics later this morning to see if something is loose. To be clear, the cutting is perfect … never had a cut not line up or be wavy or the like. Even large circle cuts and 14 to 16" cuts are perfect–they are straight and meet back up perfectly at the start. But I have never been able to engrave. I tried when I first got it and chalked the bad results up to ignorance on my part. But now I believe there is a problem and it’s killing me.

If I wanted that kind of output, it would be difficult… I’d have to draw it, so yes you have some kind of anomaly that is causing it…

Good luck


Perhaps the step polarity is wrong:

Apparently the controller can arrive from the factory (or whatever0 with an incorrect polarity set on one or more axes, so it may have never worked right through no fault of your own.

That wouldn’t account for the irregularity, but if it improves the overall skew, it’ll be a, uh, step in the right direction.

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