Looking for some tips for working with rasters on 5w diode based machine

I recently built a laser engraver using a 5w laser module from ebay and a pretty basic cartesian setup driven by a RAMPS board running marlin. So far I have calibrated it to work pretty well and can do simple jobs like cutting out a shape from 3mm plywood without completely decimating the edges, a problem that was helped significantly with the addition of a air assist system courtesy of thingiverse. My current challenge is getting rasters to do what I want. Currenly i’m printing on lite pine plywood that has been stained to an oak like texture using instant coffee (it gives me much better results and looks great) but i’m having issues on both plain and coffee’d wood where either it only prints the trace of the image as if I had traced the bitmap in inkscape when I would really like it to display some darkening on all non white parts of the image. For calibration I have been burning the starbucks black and green logo as seen below and rather than burn through all my thin wood i’d really like to hear some tips on getting nicer rasters.


It needs a lot of testing to get good grayscale results.

One tip I could give you is not only to play with power and feed but also with the PWM frequency. My experience is, that lower PWM frequency (longer period time) is better for grayscale and higher is better for cutting. The explanation is, that wood needs more time to get brown (not more power).

And a perfect focus is essential for grayscale engraving.

(I use 3000-5000Hz for Grayscale and a pixel size / tool diameter of 0.1-0.2mm)

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Thanks for the advice. For the record I was able to solve a few of my issues by increasing the minimum laser power since it would often go below any effective power rating.

Yes, thats a good point. You need to find the minimum power needed to get any color and the maximum where it doesn’t get darker. This is the range for your engraving.

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