Homebrew Laser Cutter made by Zach Radding

Step 10 Pen Plotter Based Laser Cutter

Back to Version One. Zach ordered a new digital penplotter from Roland for about $800. It understood HPGL and its own plotter driver protocol. To cut a part, Zach drew the lines and hit the "plot" button in his cad program.
The plotter went to work, not knowing that Zach had attached his laser and mirrors as shown in this diagram. This is the most common arrangement in commercial laser cutters. Zach didn't have any problem with the mirrors and would
use this arrangement again if he makes another laser cutter.
The plotter had a pen change function for different line styles. Zach added buttons at the pen change stations to tell his laser controller what sort of cut was expected. The controller then sent a PWM signal to the laser to control the brightness of the laser. The pen-up and pen-down signal from the plotter was used to turn the laser on and off.

This diagram depicts the machine as seen from above. Mirror 4 points the beam straight down through the focusing lens onto the workpiece. Mirrors 1 and 2 are fixed. Mirror 3 is attached to the (blue) x-axis gantry and moves side-to-side with it. Mirror 4 and the focusing lens slide to-and-fro on the gantry.