Homebrew PCBs

Andrew,

I've been "tilting at this windmill" for a few years on and off. So far,
none of my methods have been good enough although printing to clear plastic
mirror image came close. 

I am convinced that toner is not strong enough to hold back acid or electro
etch reliably. I do believe that a layer of wax will stop acid and electro
etch. The trick is how to selectively apply or remove the wax. The
alternative is to use a photo sensitive coating. What has stopped me there
is cost and the fact that it is already available so nothing new.

My guess is that with wax, I could etch deep enough to make it look good.
Not so sure it would work if the wax was only on the number and lines. This
is the raised approach you mentioned. That would be rather weak. But if it
did work, I think it would look better.

As to your excellent questions:

1. if a given method does not produce results as good as mechanical
engraving and stamping, then I would move on to the next method.
2. the standard approach of scribing and stamping is very hard for me to do
consistently. I might get reasonable scribe lines 99% of the time which
means 1% are screwed up and will jump out at me. With metal stamps, the
success rate is more like 50%. With a good fixture, I should be able to
improve this to maybe 75%. Still, plenty of room for improvement. 

My goal is to get consistent results with relatively low skill and certainly
low cost. It would be nice if a wax coating was part of the answer since it
meets these criteria.

As my friend Dan tells me, "I'm like a dog with a bone." When I find an
interesting problem to solve, I keep at it until it is solved.

Rick  

-----Original Message-----
From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
On Behalf Of Andrew
Sent: Wednesday, March 20, 2013 8:59 AM
To: Homebrew_PCBs@yahoogroups.com
Subject: [Homebrew_PCBs] Re: etching the OD of a cylinder to create a
graduated dial

As I said, I understand that you want to try the etching route; I was just
curious if you had also explored the other options.

Some of the later responses have detailed some reasons why the results may
not be crisp -- the problem of getting a good pattern transferred onto a
round surface; the possible problem of undercutting if you go to much depth;
the possible problem of getting an even etch at all points. The latter two
points may be especially acute when trying to produce consistent, fine lines
appropriate for machinist levels of precision -- particularly if you leave
the lines "raised" against an etched background.

None of these are intended as arguments against trying it. On the contrary,
I hope you do try it, and I hope that this discussion helps you as you
anticipate and work through possible challenges. (The latter is part of the
fun in inventing, right?) The key questions I will be interested in seeing
answered are the following: 1) Does the method produce results as good as
(or better than, or worse than) the standard approach? 2) Can acceptable
results be produced as easily as (or more easily than, or less easily than)
the standard approach?

I look forward to seeing your results.