Over the last few months, [Chris] has been machining a timepiece out of brass and documenting the entire process on his YouTube channel. This week, he completed the clock face. The clock he’s replicating comes from a time before CNC, and according to [Chris], the work of engraving roman numerals on a piece of brass would have been sent out to an engraver. Instead of doing things the traditional way, he’s etching brass with ferric chloride. It’s truly artisan work, and also provides a great tutorial for etching PCBs.
[Chris] is using a photoresist process for engraving his clock dial, and just like making PCBs, this task begins by thoroughly scrubbing and cleaning some brass with acetone. The photoresist is placed on the brass, a transparency sheet printed off, and the entire thing exposed to four blacklights. After that, the unexposed photoresist is dissolved with a sodium carbonate solution, and it’s time for etching.
The clock face was etched in ferric chloride far longer than any PCB would; [Chris] is filling these etchings with shellac wax for a nice contrast between the silvered brass and needs deep, well-defined voids.
You can check out the video below, but that would do [Chris]’ channel a disservice. When we first noticed his work, the comments were actually more positive than not. That’s high praise around here.