Problem with step loosing while engraving grayscale fotos

Hi, I am having a problem with engraving grayscale content…
I am getting a hough line shift or step loosing. This only happens with grayscale, 100% works fine as shown in the image…

Any idea? Thank you!

It seems to be Lightburn related, I checked the timing belts and the cutting and black engraving works just great, just grayscale seems to cause this extreme line shifting or step loosing on the x-axis…

What speeds do you use for “grayscale” and ordinary fill?

That’s what I was thinking, too…

I tried all kind of speeds, even lowering the acceleration with $120=150 and $121=150.
No change at all but 100% is always accurate, just with grayscale images, the step dropping is huge…
Very strange…

With the same settings for a pure black image and a greyscale image…

Not to put too fine an edge on it, but exactly what speeds are you using?

Copy and past the contents of the Console output for the $$ GRBL command so everybody can see what’s going on.

It would be helpful to see the *.lbrn2 files for those testcases: please upload them, too.

Thank you, this is the file from my latest test…

Changing the image mode has no effect, same step dropping…

And the GRBL $$ configuration too, please.

Sorry, I am not home for the moment and will be back next week… I only have my Mac here, not the laser… Will post it asap!

Thank you!

You gotta start packing larger! :grin:

Sorry for the delay, just came back home…





















































The Wetransfer link has aged out. You can upload *.lbrn2 files to the forum here with drag-n-drop or the upload icon in the reply editor.

Do that for the two files producing “good” and “bad” results.

Go through the list of all the other things that can go wrong. Although everybody wants to believe the hardware is perfect, very often desktop diode lasers have loose screws. LightBurn layouts with different speeds and scanning patterns can trigger different mechanical problems, so it’s worthwhile to eliminate those.

For example:

Note that the loose screw got through the initial “checked all the mechanical parts and they seem fine” assessment. :grin:

Although it’s written for Sculpfun lasers, you’ll recognize most of the parts and places where problems lurk:

A thorough checkout can save many hours of back-and-forth.

Thank you!
About the mechanical adjustments:
Its all fine, perfect path cutting and black engraving…
Just grayscale seems to loose a lot of steps…

Please find the file here, its bigger than 4 MB so I have to use an external link…
LB File

Will do another test setup with grayscale and pure black in one file tomorrow…

Here is the file, the black one works fine,
the foto is loosing steps…

Not sure, but the only difference I can see is the dynamic acceleration for the foto…
The black image has a constant acceleration…

LB File

What you are seeing along the vertical edges of the photo comes from the 0% Min power level. The photo does not have constant gray levels along the edge and the power delivered for lighter shades falls below the level required to char the wood. The wood grain and surface treatment also affects the results.

You can test this by engraving a pure black-to-white vertical gradient and matching the edge against a vertical line.

Thank you…
It happens in Jarvis mode too…