Grayscale Image Engraving on Boss HP-3655

Hello. I am new to lasers and I’m looking for help with trying to engrave a large image on cast acrylic. Currently I have been using the dither setting buy would like for it to be a bit more realistic and not have the dots as noticeable. So I switched to Grayscale and turned on “shade according to power”. My problem is transferring the file from LB to the machine. Once I send it to my laser the preview screen shows a black square. No matter what I do the preview is always black. Would anyone happen to have any insight as to what I am doing wrong? Thanks in advance.

There’s absolutely nothing wrong - that’s how a grayscale image will look on the preview. It won’t matter much - engraving grayscale with a 100+ watt laser is going to give you variable depth, not variable shading, even on wood.

On acrylic, shading comes from marking the surface, not changing the color (like with wood), so even with a weaker laser you won’t get grayscale to work on acrylic.

Well that explains things. Would it be possible for me to send a sample file for advice on the best way to engrave it on acrylic?

What is the wattage of your machine? I’m assuming 150w, which is going to limit your options quite a bit. Engraving photos with shading requires a gentle touch, and you have a bazooka. :slight_smile:

You’ll likely be in the 100 to 130 DPI range, with the lowest power you can reliably use to just touch the surface. There are some settings you can use to help:

Import the original image into LightBurn. Select it, right-click, choose ‘Show Properties’. Then set the following values:

  • Gamma : 0.8
  • Enhance Radius: 4
  • Enhance Amount: 150
  • Adjust contrast and brightness if necessary

Then, in the cut settings, set:

  • Stucki or Jarvis dither
  • Power & speed as appropriate

The gamma setting will help reduce the effects of overlapping dots. If you increase the DPI, you can reduce the gamma to help compensate a little, but it can’t make your beam spot any smaller - it just increases the brightness of the mid-tones.

The enhance settings will increase the edge detail a little. 150 is a starting point, but you can increase that to whatever suits you.

Be aware that image engraving even on forgiving material with the right laser takes patience and practice. Acrylic is not forgiving, and a 150w laser is not the right tool. You’ll be able to do it, but I want to make sure you understand that you won’t be able to get the same kind of fine detail that someone with a 40w laser can.

Thank you so much for the advice. My machine is 150 watts and definitely not suited for this but i’ll do the best I can. So far the results aren’t bad using dither but I would like a little more crispness around the moon and clouds in the image. I’m also aware that the results will not be the same as a lower power machine and that’s ok. I am perfectly happy with experimenting and learning. After I run a sample with your suggestions I’ll let you know how things turned out. Thanks again for your help.

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