I have a Monport 60W CO2 (Ruida controller), with autofocus and air assist. I obviously use Lightburn for the software side.
I’ve been working on creating some leather stamps from acrylic (1/4"). My designs are pretty simple and geometric, so not high detailed at all. I’m able to get a deep engrave with 3-4 passes, but the issue I’m running into is that the engraved areas are very bumpy and rough, almost like a topographic map, to the point that it ends up showing up in the leather when I use the stamp.
The best results (but still very far from good) have been running a speed of 250mm/s and 50% power, with 5 passes. 2 vertical, 2 horizontal, and 1 at a 45 degree angle. Without the last pass, the stamp would’ve been unusable…even with the 45 degree pass, there are still problem spots.
I’ve tried running with and without air assist with no real difference. The acrylic I’m using is cast, not extruded. I leave the paper on both sides and burn through the top layer, and leave the bottom paper on until it’s complete.
I’m not really sure where to proceed from here. Anyone have ideas on what I might be doing wrong?
A laser doesn’t operate like a milling cutter: it does not have a definite end making a clean cut.
Instead, the focused spot blasts material off the surface, with the departing swirl of gas / debris / vapor / ash / whatever leaving a surface looking like it’s been chewed.
You can try fiddling with the focus, as a blurred spot may leave a somewhat smoother surface. This will affect the line interval, because the spot will be bigger, and (as you found) plowing the same field along different rows with different spacing may help.
Filling the bottom of the final engraving with a thin epoxy layer or, perhaps, melting it with a solvent, may reduce the remaining roughness.
On lower power (diode) lasers there’s a way to somewhat cheat on homogenous materials by using low power/high speed/multiple passes in order to adjust the engraving/cutting depth.
Coupled with the defocusing @ednisley suggested, might be worth a try.
I’d probably also look into using other materials for the stamp.
Even without any experience engraving acrylic with a CO2 laser, I’d be willing to bet it will be a PITA no matter what You try when any kind of predictable surface roughness is the goal.
Definitely possible though, there seems to be tons of of laser engraved embossing acrylic stamps availabe online.
So, as there’s a lot of different varities of acrylic available, it might just be a matter of finding the exactly right acrylic material to be engraved.
I have used a small dc motor with a router bit and have had some success,but because most laser frames cannot handle much weight you must run very slow so that the bit can cut its way without too much resistance.
