295 Speed
80% Power
Map Grays to Power
Min Power 0
340 LPI
Focus Height 0.356" (defocused 0.120" over factory PG setting)
2 Passes
I have to re-visit the depth map file because both eyes should have been completely clear and the stitching over the mouth should be clear as well but that detail is so tiny it just got washed out in the laser process. Think I might try this again without defocusing at all so those details dont get burned out.
I included a photo looking into the edge of the acrylic so you can see how deep this went.
Also, a note about 3D Engraving in general. The overall size and thickness of the piece will impact how pronounced the depth looks. ie, if this were made on 1/8" material instead the depth obviously has to be scaled back, but even if it was kept on 1/4" material but I sized it to 3" diameter instead of 1" diameter, the transitions in depth also scale out and reduce the “steepness” of the detail, unless you build the depth map to compensate for that, at that specific size.
More tests, and a big improvement! Turns out that changing the focus height to BELOW the material thickness works better!
@Tom_A you brought up focus in the other thread about and looks like focus does play a part but when I tested more defocus, I should have gone lower, not higher!
They’re the same bands that appeared on my other acrylic engraving tests that I posted.
Not sure if it’s because of trying to get 256 levels of gray into a narrow (1" wide) strip and power modulation of the laser while it’s on the fly, or related to stepper motor stepping, or something else. However, remember the one test I did with the artwork rotated 90 degrees did not have the same banding, where the laser power was consistent the full length of the X-axis movement.
One thing I’d be curious to test is the power switching speed of the Glowforge, swinging from 0 to full power, and how fast it can accomplish it. I think that would be a good test to add to a Glowforge test pattern diagnostic.
@mpipes thanks for the experimentation and write-up.
I cannot tell you how much money and time, you and others are going to save the rest of us when we finally get our machines.
Many Thanks
You mean like a serration? This is a glue-up of 3 pieces of 1/8" acrylic. This was an early test and was running full power and pretty low speed to hog all this out in a single pass, so it’s not a very clean run LOL.
Not necessarily a serration (which implies a gradual ramping of low to high power), more like black and white bars at a high resolution/LPI at the fastest movement speed. The question is what material to use, I suppose, that can take the full energy blast and keep some sort of detail to it for evaluating when its complete.
Acrylic is probably not a good material to use for testing it, though… It would retain too much heat and just stay too molten.
The laser can switch on/off instantly without any power ramping.
With acrylic, the very top ledge of the cut will form a tiny radius. Here’s a photo of a sample from my other acrylic testing thread that shows a close-up view if you download the full size image.
You have me curious though if it may behave differently for a repeated pattern.
You don’t know how much your generous efforts are appreciated @mpipes. You probably saved me a sheet or two of acrylic and a several frustrating hours getting to this point. Thanks man.
This is non-PG .23 acrylic (from Inventables I believe) set at 295/80 at .1 focus. It was my own hand-colored greyscale image and I’m really happy with the first effort.
Some of the lines in the engrave are from the blending of the image and not the GF. The weird line at the elbow and the blowout at the bottom of the foot was from a mis-start and those areas getting three passes, not two. I fixed some of the blending and made a few other adjustments and I’m cutting it again at 295/80/.07. (The GUI pic is of the 2nd attempt.)
I’d love to see some of your skeletons done in 3D too.
I could hear Jack calling my name while I was unsuccessfully trying to fall asleep tonight, so here I am 2:00am taking photos of him lit by LED. The LED is blue, the other two pictures I just laid transparent fluorescent acrylic in front of the LED to color it.
