Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

Hi
This is going to sound a little OT. I've gutted a Epson 400 and a
scanner with 2 guide rods. I'm putting the print head and drive
mechanism on top of the scanner motions system. I'm doing this to make
a flat bed printer - like a flat bed scanner. Since I'm working on a
system that prints onto boards to make PCBs, I'm hoping this is not to
OT. The hitch I'm hitting is finding gears, axles for the gears, and a
belt drive system for the X axis so that I can change the paper drive
system to moving the head/head movement system. The paper drive uses a
stepper that worked through 3 gears down to driving the paper roller. I
don't have the gear ratio yet. My eyes started crossing before I was
done counting ;). The problem is the final gear (that is on the
roller), which has an I.D. of about 5/8", way off of anything I can
use for an axle. I searched around for "small gears" and "robot gears"
on vivisimo, but the stores I found did not have much of a selection of
gears, and no timing belts of the right size (I need about a 26" timing
belt).
I'd appreciate it if anyone has any info on where to get these
components.
Also, I'm using the printers X axis (paper roller control system) for
easy interfacing. In effect the printer electronics won't know there is
any change. I'm not real happy with using a belt drive, since it will
stretch, and the print head & drive (Y axis) mechanism have a bit of
mass. This is going to be slammed around every time the printer moves
the head down a line, but I have to be able to intervene when I get to
the bottom, I need to grab the head and move it back to the top whenever
the printer does a page feed. I want to do this by having a mechanism
that essentially unhooks the normal drive servo system and moves the
head back when it detects that the printer is form feeding, then
unblocks the optical sensor that checks when the paper feed hardware has
done a complete cycle and unblocks the paper present switch.
If anyone has any ideas about a way to get around using a belt, I'd
appreciate that to, or an idea for which newsgroups to search. I looked
for the 2 member epson_400_and_optics_9600_pcb_printing group but
couldn't find it ;).
Richard