Homebrew PCBs

Andrew,

I know that photo etching has been done on flat plates so assumed it could
be made to work on a cylinder. I would wrap the artwork around the cylinder
and rotate it at a constant rate under the UV light. The missing link here
for me is an easy to apply photo resist. I've always used pre-treated
circuit board material and had good results. 

One option I may pursue would be to coat the cylinder with wax and then use
engraving techniques to scribe through only the wax. In this way, mistakes
can be fixed by reflowing the wax. Not sure how to do the numbers. This
method probably would work but is too much effort for me. If a spray-on
photo resist could be made to work, that would be the key.

Rick

-----Original Message-----
From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
On Behalf Of Andrew
Sent: Wednesday, March 20, 2013 9:56 AM
To: Homebrew_PCBs@yahoogroups.com
Subject: [Homebrew_PCBs] Re: etching the OD of a cylinder to create a
graduated dial

I went back and looked at some dials, and revised my estimate -- I think a
line of .005" to even as much as .010" would be acceptable, unless the dial
is very small. I have made a sample PCB using.005" lines with TT, but it was
pretty iffy.

If I understood correctly, you said that a photo resist method of etching
dials has been done? It would seem like this would be the best approach for
etching. Perhaps a spray-on photo resist would work well?

I've not worked enough with wax to have a feel for how well that could work,
either in terms of transfer or in terms of resist.

Again, I look forward to what you come up with ...