James Cooper - Peach Printer Software Engineer Chimes in

[Slatye]

I always wondered why you need to turn the laser on and off at all. Why not have a small disk with different sized openings (and a part of it w/out any opening) in front of the laser. Rotate 30 degrees to select a small opening for the laser, 60 for a large opening (infill) and 90 degrees to block it completely. Or something like that.

Probably just because of speed. Even a super-quick servo will take maybe 100ms to get reposition the disc, whereas the electronics to turn the laser on/off can probably operate in microseconds easily. Then there are all the issues with fast mechanical devices - wear and tear, backlash, vibration, electrical noise (digital servos do horrible things to the power supply lines). Finally, if the disc is blocking the laser, either it's absorbing that energy (and warming up) or it's reflecting it (potentially onto something that won't appreciate a lot of UV light, like the bottle of resin sitting next to the printer).

[Morten]

Probably just because of speed. Even a super-quick servo will take maybe 100ms to get reposition the disc, whereas the electronics to turn the laser on/off can probably operate in microseconds easily. Then there are all the issues with fast mechanical devices - wear and tear, backlash, vibration, electrical noise (digital servos do horrible things to the power supply lines). Finally, if the disc is blocking the laser, either it's absorbing that energy (and warming up) or it's reflecting it (potentially onto something that won't appreciate a lot of UV light, like the bottle of resin sitting next to the printer).

Great reply, thanks! I was thinking more of doing it the same way that the mirrors already move, a black disk on a string with several different sized apertures and a blocking part, but can see it would be way to slow to raster with and maybe heat up too much (altho I'm not sure, you would only block the laser every so often).