Im using a 10watt+ endurance laser on a Lulzbot TAZ5. After i installed and was able to make the laser work, i started experimenting with lightburn settings and tried to engrave an image on a MDF board. At the beginning i was not getting the results that i wanted, i tried several set ups but none of them gave me the result i was looking for.
As a starting point i was using some of the settings other users were using in their machines, but i was not getting what i wanted, therefore i decided to approach this from a simpler perspective. The purpose of this was to understand how the gray scale works with the laser.
I created a simple gradient without blending the different tones of gray, this way i was able to identify where the laser had to increase or reduce its power (i was worry that my laser was only burning at one constant intensity). knowing that white is 0% and black is 100% (or the value used as max power) i only used 10 different tones from white to black, so i can divide the % max power by 10 and know more less which intensity is each gray.
Something that i discovered is that when the max power is not at 100% the grayscale is less evident, i’m guessing its because it has a shorter range in between grays to work with. This creates a small issue because if the engraving has to be done on a thin material, the 100% max power is going to cut the material instead of just engraving it, something to consider when deciding to engrave thin materials.
I decided to leave the max power to 100% and play only with the speeds (the mdf is 20mm thick, so i didn’t worry about the laser cutting through the material). DPI is set to 50 so each line is separated from each other to avoid the burning to become a big spot. Angle is 0º so the line is parallel to the gradient.
I found out that my first mistake was that i was using the laser at a higher speed, even though many other users were getting good results going faster. After engraving at 5 different speeds and comparing the results, was time to change the angle of the scans, that way the laser had to change intensity during each scan.
I used the same power, DPI and speeds as my test before, but changed the angle to 90º, this way the laser had to go perpendicular to the gradient and during each scan change its intensity. the photos don’t show fine details of the engravings but the first tests were more successful. In both tests the speeds between 1000-1500 seem to work better. I still don’t know how to avoid the darker burn when the laser finishes a pass and starts the new one (the darker edge).
Rarely the gray scale is going to be this simple therefore i decided to engrave an image. Knowing now that the speeds were too fast for my set up, i applied the speeds that worked better in the last couple tests. I chose an image that had fewer white spots so the laser had to be “on” most of the time.
I grabbed the original image, then converted it to grayscale and finally to bitmap. In my very first attempts i discovered that to get better results using other setting than grayscale in lightburn, the image has to be converted to bitmap.
Did a couple of tests at 1000mm/m and 1500 mm/m but the gray scale still was not as i wanted to be, so i decided to try the jarvis setting on lightburn to compare both. I liked it better than the grayscale, i decided to do more tests with it and with other settings in lightburn.
Until i find a result that i like with the grayscale setting, i’m going to use jarvis or newsprint.