Luban 3.6.1 and Greyscale for Laser Engraving

Snapmaker 2.0 A250
Snapmaker Luban 3.6.1

bug 1: Luban resizes every image when loaded, forcing user to adjust size regardless of original
bug 1.1: Resizing requires changing both X and Y, dimensions are no longer locked (this should actually be an option controlled by a checkbox)
bug 2: Processing converts Greyscale to Black and White. Any attempt to preview/generate gcode results in the greyscale image being displayed (and printed) as if it were incorrectly loaded as black and white. Very dark! Altering contrast and brightness helps, but severely distorts the original image.
bug 3: No settings are saved between sessions, and there is no option to create a profile (this is noted elsewhere on this board, but it is worth repeating)

I will go download an older version to see if this is a new problem. For the record, I’ve completed the sample project (box) and successfully generated a black and white engraving. Only greyscale has failed for me.


I’m down to version 3.4.2 and seeing the same behavior. Have tried multiple images with little luck. Converting to greyscale in GIMP before importing in Luban makes no difference. Downloading sample images (so I know it’s not my own images fault) has the same result.

Anyone have any advice?

Screenshots of what is happening here, first, the images loads just fine


Selecting process displays the image as I would expect it to end up

However, looking at the preview and generating the gcode… this:

Same issues here. I must say, between not being able to print anything successfully on my A350 I am so disappointed in spending the money I did for this product. It is my 5th printer, and this one by far performs the worst. I will be monitoring this thread in hopes of a fix…cant even laser print one thing…

Try to scroll in the picture, it’s getting lighter then.

Have a look at this (it was pretty dark in the overview, but when scrolling in to the “original size” it was like this)

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Thats reassuring, however its weird OP said it print B&W. I can confirm your suggestion is true. Might have to bite the bullet and try the print.

I am having the same problem with Greyscale, had to go back to Ver 3.3.3 to get it to work (but then the enclosure options are not available for light, fan and door sensor).
Also agree about the sizing, in previous versions you only had to alter either X or Y and the corresponding figure altered in relation to it keeping the correct aspect ratio, please can this option be returned.

I am not sure what you are telling me. I’ve tried shrinking the original image to 1/4 size and blowing it up in Luban, no change. Please describe in detail what you did to successfully print a picture. Start with image type, resolution, and dimensions if you can, please?

In the meantime, I’m going to try to “dumb down” my starting image to see if that helps. Learning GIMP as I go.

I did discover that you can shift-drag and it will scale evenly, but no fine tune options dragging with mouse.

I tried the print, came out as dark and nasty as the preview promised.

I actually loaded 3.3.3 to another computer to try, since that was the version shown in the demo. It didn’t work any better, but I didn’t try tweaking it much at all before I gave up in disgust and poured myself a drink.

Do you mind sharing your picture file? I am using 3.1.0 and have not had that issue with the darkness that others are experiencing.

Original:


Black and White version (GIMP Image/Mode/Grayscale):

Reduced dimensions:
maldita_bw_half

Change your density setting and that should help a lot.

Doesn’t the density reduce quality?

Hey, all in all, i don´t want to make a showcase of this.
Fact is, if you want a perfect picture you need to do some trail and error, especially if it is a huge laser engrave.

In my case i did a research of three days, varying in laser power, dwell time and work speed.
Also tried other laser focus.

The most important thing at laser engraving is the quality of the picture.- No Whatsapp image!
You need the depth and contrast of the picture, for a perfect laser image.
I had a picture size of 4545x2395pixel 72dpi 24bit depth.

The next important thing is, you have your own material, nobody could help you at this point,- you have to figure out the parameters on your own.- Material out of the same wood would not be the same, not even from the same tree.

Hope this helps!- Do some tests!

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As @xchrisd said, its really a matter of trial and error to find the correct power settings for the material you are using.

I have found that engraving at 65% power on plywood gives good results. Try that as a starting point and fine tune.

I would suggest you load up an image and start engraving and during the job, alter the laser power through the touchscreen to have side by side comparison as to the lightness/darkness vs laser power.

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When I load the image, it does not resize the image.

Considering Processing converts Greyscale to Black and White, it is due the the computer screen is small. If you adjust/enlarge the image, it goes better.

This is my first trial print. I would sharpen just a bit in a photo editor and maybe darken just a bit some of the lighter parts so that they engrave a little better. It is just a matter of trial and error until you get something that looks good to you. I buy cheap wood panels just so I have a lot to play with for test printing.

Thank you all for the input, I continue to tweak it as the heat in my garage allows :wink: Did manage to get a decent print (albeit fairly light) on cardboard by simply lowering the density (thanks, writrchick_35!). Still unsure what Chris is referring to when he says “zoom in”, as that literally does nothing except enlarge the image in the view.
I’ll keep at it and let you know when I figure out whatever my stumbling block is.

Thanks for the answer by @xchrisd . here I’m answering the original post as they are asked very frequently:

bug 1

  • Luban resizes every image when loaded: This is the default behavior of Luban to display the image in a proper size, we usually use images like 720P or 1080P, but when converting the image to G-code, we must know what resolution it is to be fitting in a 250x250 space (A250). The background axes and grids are showing in millimeter (mm) unit, so the image is scaled down to size of <250. It should be noted that scaled size is just for displaying the image in editor, its actually size and density parameter are used when generating G-code.
  • Resizing requires changing both X and Y, dimensions are no longer locked: Uniform/proportional scaling is under development (v3.9.0). You can checkout the github repo or Snapmaker Public Roadmap for our recent plans and actions.

bug 2

  • Processing converts Greyscale to Black and White: as discussed above it’s the zooming issue of the 3D scene, closer you are to the image, the lighter color it is.

bug 3

  • No settings are saved between sessions: When considering the problem, we found that laser/CNC objects are different than 3D printing. Objects in 3D printing share a single common profile, but objects in laser/CNC each has its own profile (say one to be engraved and one to be cut). We are on the way to add object management feature and session saving functions to the editor.
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