Homebrew PCBs

I am now working on producing ds boards. My first test was to see if 
I can print multiple times on one side of a board with good 
registration. If I can do that, I'm certain I can do the rest. I 
added a reflective sensor to locate the actual position in the motion 
(Y) axis. I could have used one of the leftover E260 interrupter type 
sensors, but it was easier for me to use black tape an white labels 
than to drill holes. In the final version, in the spirit of 
recycling, I might use a leftover.  There are some pictures of the 
sensor and new mcu board on my pbase site <http://www.pbase.com/mark10970>.

As I mentioned previously, when the carrier moves through the 
printer, the leading edge first hits the moving transfer roller, 
which pulls it up into the drum/transfer roller interface. This 
causes a variable delay, which messes up the registration. The "fix" 
is to wait till a couple of inches of carrier is completely through 
the interface before starting the actual timing (timing starts when 
pis is pulled low).  I still have some work to do, but I'm pretty 
sure I can get it to work I printed a test with 5 mil traces - it was 
perfect in the Y axis, but about 5 mils off in the x axis. There is a 
picture on my pbase site.

One problem I foresee is how to tell whether the sides are registered 
before etching. You can't see through the board before it is etched, 
and you don't want to etch it without knowing it is correct.

Mark