Laser Printing UV Resin
A laser printer uses a rotating mirror to project it's laser beam across a light-sensitive drum. I won't go into the way that painting the drum with light, results in a paper page being printed, because of course that is not what this article is about.Instead lets look at the idea of using a Y-Z cartesian bot, to translate the electronic image that the laser raster creates, into cured UV Resin.
The issue is how to draw the UV laser image along the tank, in order to create a raster graphics exposure of UV resin, and how to raise the build platform from the tank as the resin is exposed. I propose to draw the laser print-head along the Y axis of a Y-Z cartesian bot, and use the Z axis of the cartesian bot to raise the build platform, borrowing liberally from existing REPRAP technology to achieve it.
There are a couple of design factors that need to be taken into account.
- Z axis (Vertical Jack) design
- Y axis (Horizontal Scan) design
Z axis design
RepRap has dealt with the Z axis design a couple of times, and I think the Mendel/Prussa design with either mechanically or electronically linked 1 jack per side, and polished rod with sprung bearing followers or bushings, is an effective design.However to make the Z axis a bit more rigid against horizontal torque, I thought, that use of a 2 polished rod/side design might be better. This might be overkill, I note the commercial units have a single central support, but due to amateur building, I feel that this might not be as accurate when converted into a kit.
By making the Z axis platten wider, I thought we could support and stabilize a larger build platform
I am guessing we can make this platform and the Z platten light enough that when we use the Prussa-like top-mounted steppers to turn the screw-jacks, we can keep the amperage low.
I thought, that using surface mounted threaded rod, attached to the build platform, and extending up to the Z axis platten, would allow us to suspend the build platform into the tank.
Y axis design
The Y axis on the other hand is a bit trickier. The main problem is to link the Laser printer electronics raster based image to the advance of the Y axis, in such a manner as to synchronize raster and scan. Essentially what we need to do, is to tune the speed of the stepper motors to the raster scan. One way of doing this, is to use the rastor completion signal as an advance The actual steps/raster should be relatively similar from one advance to another, simplifying the bot firmware.stereolithography