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Open Discussion / Laser Etch + Acrylic Backfill finish
« on: January 14, 2021, 01:38:45 PM »
Dave (pickdropper) sometimes does this kind of finish, but he has the big-boy laser and lots of attention to detail. I have neither, haha. But this is a lazy-man's pickdropper fancy finish technique. 
Used a really cheap hobby laser engraver to cut through enough powdercoat to squeegee some acrylic paint in there. The software sucks and alignment is dodgy, but for DIY it's not a bad option.
For this first test, I just did a single pass at max power (3.5W) to see how it would work. Used a toothbrush to clear the ash, wiped it down, and then dabbed some white acrylic paint at the top. Used an old credit card as a squeegee to pull the paint downward and into the crevices to fill. Sort of like silkscreen work.
I let it dry and then wiped gently with 90% isopropyl to clean up the residual paint. It's not amazing, but I'll take it for a first try. The alignment is obviously off-center, but it's close enough that I can still build it. I think I figured out a way to print a template to verify alignment better, but I'll test that later.
Circuit details: It's the DIY classic Bazz Fuss circuit with some fun tweaks. Instead of an integrated darlington transistor (usually MPSA13), I did a discreet darlington with two germanium transistors (for mojo). I used the 2n211, which is a low-gain NPN germanium transistor available from SmallBear Electronics. It's a weird package shape, so I made my own part in Eagle CAD because nobody has a footprint available. I also added a gain control pot and a toggle switch to select between standard silicon and schottky diodes.
Sounds pretty good to me, but I love the base circuit. Adding in germanium mojo and some mods for flexibility is just icing on the tonal cake. I have a few boards left if anybody wants one to mess around with.
Used a really cheap hobby laser engraver to cut through enough powdercoat to squeegee some acrylic paint in there. The software sucks and alignment is dodgy, but for DIY it's not a bad option.
For this first test, I just did a single pass at max power (3.5W) to see how it would work. Used a toothbrush to clear the ash, wiped it down, and then dabbed some white acrylic paint at the top. Used an old credit card as a squeegee to pull the paint downward and into the crevices to fill. Sort of like silkscreen work.
I let it dry and then wiped gently with 90% isopropyl to clean up the residual paint. It's not amazing, but I'll take it for a first try. The alignment is obviously off-center, but it's close enough that I can still build it. I think I figured out a way to print a template to verify alignment better, but I'll test that later.
Circuit details: It's the DIY classic Bazz Fuss circuit with some fun tweaks. Instead of an integrated darlington transistor (usually MPSA13), I did a discreet darlington with two germanium transistors (for mojo). I used the 2n211, which is a low-gain NPN germanium transistor available from SmallBear Electronics. It's a weird package shape, so I made my own part in Eagle CAD because nobody has a footprint available. I also added a gain control pot and a toggle switch to select between standard silicon and schottky diodes.
Sounds pretty good to me, but I love the base circuit. Adding in germanium mojo and some mods for flexibility is just icing on the tonal cake. I have a few boards left if anybody wants one to mess around with.
