With the ability to engrave my own backlit switch plates mostly worked out I am replacing all of the laser engraved plates. The laser left a residue of decomposed plastic that muddied the edges of the lettering. This also gives me a chance to fine tune each plate for appearance and readability. I also managed to leave off a switch for the Taxi light in the first version. This will be added.
Sat and Sunday time were limited. I was able to complete all but two of the switch plates. Two more to go. Then I can decide if I want to redo a few to correct very small defects on a couple of the plates.
Just for posterity here are the parameters I zeroed in on as I ran many, many trials Engraving bit = 0.5 mm upcut spiral Engraving speed = 7 ipm Engraving programed cutter size = 0.01 inches Depth per pass 0.015, Total depth = 0.025 14-point font Cutting speed for separation and holes = 25 ipm Depth per pass = 0.045 Plastic thickness = 0.135
As I add more text here, I just finished the last of the improved switch plate engravings. After many fails, (thus the many hours) what I learned was that the plastic stock was not perfectly flat. There was a variation in the surface to be cut of up to 0.020 inches. It might not sound like much, but with a cutting depth of 0.015 inches, an error on the minus side gave a first cut of 0,035 if the cutter was zeroed at a low spot. That will break and or melt plastic onto the cutter and burn the surface. 20 bits broken.
What I finally did to compensate was a pre-cut of 0.005 with the cutter zeroed 0.010 high. Then the 0.025 programed cut. Having deeper areas is no problem since the plastic is 0.125 thick.