Too many things have gone wrong with this old FormLabs Form 1+ laser resin 3D printer for me to think I could return to precision printing duty. A broken resin tray tilt motor was just the latest discovery added to that pile. But it’s such an interesting machine to take apart, filled with precision components that I don’t know how to use but couldn’t bear to pitch in the garbage. Top among this list is this laser optical core.
A precision machined piece of aluminum is home to four important optical components: The laser itself in a black cylinder, emitting a beam to strike two mirrors. Each mirror adhered to the end of two orthogonally mounted galvanometers. After bouncing off these two rotating mirrors, the beam strikes a small front-surface mirror directing the beam into the large center cavity. In that cavity is a much larger main mirror, who is angled to deflect the beam up into the resin tray to precisely harden some resin for the print.
Before I removed the core, I ran the optical path one last time. In place of the resin tray, I have placed a sheet of normal white office printer paper. I had no concept of the power level of this laser and wanted to see what it would do. The answer: no hole, no fire, no smoke, not even a little brown singe mark. Just a bright dot. I suppose it is possible that this laser isn’t driven at maximum power, but I am comforted to know that my initial fear of rampant laser destruction was misplaced. However, I will continue to assume it is powerful enough to cause eye damage and deserving of respect.
When removing this optical core, take care not to just blindly loosen every visible fastener. The three most visible fasteners are actually holding the laser and galvanometers in place. The galvanometer fasteners can be loosened in order to rotate the galvanometer to center their range of rotation and thus center the beam. I don’t know if similarly rotating the laser module would accomplish anything.
To remove the optical core, we actually need to unscrew the two deep set fasteners in opposing corners. These fasteners provide the force to hold the optical core in place, their orthogonally opposite corners host two alignment pins to locate the optical core on the printer chassis main spine.
At the moment I don’t know the electrical requirements to driver any of these three components, but I will try to keep this fragile optical core intact in case I can return with more knowledge about how to make them run. I also want to keep the Z-axis assembly, which is thankfully more robust than delicate optical components.