Homebrew PCBs

1st: if Eagle doesn't produce a DRILL file, chuck it, I can't remember if it
does.

2nd: if you are going to go into programming, might as well follow the
conventional technique using steppers, that way you can copy existing code,
same thing for the stepper motor control circuits.

3rd: you can use the same technique as the others, but drastically reduce in
size everything, that in itself will make a LOT of things easier, for
example, a 12" rod of aluminium 1/4" thick will be plenty for you.  Same
thing with the screw, a 1/4" diameter screw would be fine.

4th: make it all out of wood, REAL easy to cut & drill, using holes in the
wood as bushings for the rods.

5th: polish the aluminium rods slightly, just to give them that extra shine,
which translates into less friction (maybe a little dab of lubricant).


Myc, I've looked at a lot of ways to skin this chicken, and if you have a
DRILL file, can program PICs, can download the file, can assemble a basic
stepper controller like this one:
<http://www.xavierkamial.com/Videos/Stepper%20Motor%20Controller.htm>, then
steppers are the way to go.

Everything is out there for a rinky-dink system, I am just looking for
something with a little more ooomph.  But for drilling, el-cheapo steppers
cost no more than $5.  Using servos, you'd be all alone in left field, with
probably no samples from the web to get ideas from.  With steppers, you'd
get pretty darn close to the same precision as a lot of us will get.  The
only difference is that we will be able to maintain that precision over a
longer surface; which you don't need anyways.

Robert
:)



-----Message d'origine-----
De : Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com] De
la part de mycroft2152
Envoyé : juin 11 2005 20:10
À : Homebrew_PCBs@yahoogroups.com
Objet : [Homebrew_PCBs] PCB Driller - Looking for comments


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







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