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

Hi Guys,

I've been following the pcb driller discussion. I've been wanting to
build one for a long time. But so far the designs seem too complicated
or too heavy duty for my needs. And too expensive too. I want to throw
out a couple of ideas. I'd appreciate any thoughts on them. (Yes,
Stefan, I wouldd like yur thoughts too, as long as they don't include
anything about a chicken grill. :)

I use EAGLE free version for my boards. That means they are under 3" x
4". When drawing the layout, I set EAGLE at a 0.10" grid (sometimes I
cheat and go 0.05"). I lay out my components to fit this grid. This
works well, but I don't like to manually postion the board for driling
on my drill press.

It occurred to me that what I needed was something that could drill
holes on a 3" x 4" grid. At 0.10" spacing the grid would be 30 by 40,
and on 0.05" spacing the grid would be 60 x 80.

I will say, for now, I am not interested in milling, just drilling
holes. And I would be willing to "pull the handle" on the drill press.
My boards are small enough with not too many holes. So what would it
take to build a grid based driller.

My first thought was converting an old printer. Attaching a small
dremel to the print head. I would move the print head across the page
stoping at the appropriate spot and the pulls the handle. Afte all the
holes on one line were drilled, go to the next line. After all if you
cn print a grid of dots on a page, you could move the print heaad with
simple commands.

The second idea I had, after looking at all the drivers chps and
software and discussion about half stepping and choppers, was that the
driller could be very light duty due to the size of the board and the
coarseness of the steps.

Looking at the old Nasa stepper design, that uses 2 flip flops and a
couple of nor gates, I realized that 2 lines would be all that i
really need for single stepping.

I've been playing woth the PICAXE chips. They are programmed in basic
and only need a 3 wire cable for programming. Best of all they (the
08M)are only about $3 each, and has 5 i/o lines.

I've been thinking about using one of these as the controller. If I
download the coordinate of the holes, program, The PICAXE could
convert the coordinates to steps I could position the drill using just
4 of the 5 lines. The 5th line would be an input to start or go to the
next holes. A driver chip or transistors would be needed for the power
to run the servovs.

For the driller bed, a light duty X-Y table about 6" x 6" could be
driven by some small servos and screws.

It would be a small, inexpensive, semi automatic pcb driller.

What do you see as the pitfalls with these two ideas?

Myc