On Thu, 21 Mar 2013 11:18:29 -0700, you wrote:
>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.
Try a pantograph and larger patterns to engrave the numbers. Another
option would be Laser engraving. You need to rotate the cylinder and
move perpendicularly to the axis. Same thing for normal engraving.
Might be worth the effort.
Harvey
>
>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 ...