Brass to Bits
Minnie’s name plate is finally finished! Let’s start with the finalé and work backwards :
The black is high gloss automotive paint. I sprayed a nice thick layer over the entire piece, let it dry, then hit it with an orbital sander to remove the excess. A thin layer of clear-coat will hopefully keep it from tarnishing.
I had initially tried a more conservative shot of enamel, but it didn’t like the clear-coat. So one acetone wash later and it was back to the spray booth improvised from the remains of that old janky laser cutter.
Here’s the piece before sanding:
The brass cut pretty cleanly on the cncbot. Before I ran the cut in brass, I did several tests in plywood, which cuts like butter. For best results with brass, the rule seems to be SLOW DOWN AND USE MORE LUBE.
Before plywood, I simulated the gcode with Cutviewer to make sure I didn’t have any obvious mistakes:
The gcode was generated in CamBam (not free, Windows only, but reasonably priced and very easy to go from simple DXFs to mill-friendly gcode). The UI is pretty basic, but it has some nice features like auto-computing cutout tabs and integration with Cutviewer.
The rest of the toolchain is better left un-blogged. It’s ugly.
The DIY 3D printing world is fairly well covered with good software at this stage. But the path from bits to atoms via milling machines seems to be strewn with the debris of good intentions, abandoned java blobs, questionable firmware, and people who think that running Debian 3.0 on a 486 with a parallel port is the pinnacle of desktop CNC.