Homebrew PCBs

--- In Homebrew_PCBs@yahoogroups.com, "Nick" <njacovou@o...> wrote:
> Thank you all for your responses.Most usefull.

Nick,

Here's another technique I useta use, which I didn't have time to 
post before...

It also involves using a perf board and laying out your board at .100

First make an accurately sized photocopy of your final PCB layout.
Then--using light from behind, as you described for a different use-- 
line this up with a piece of perfboard at least as big as the entire 
board. Now peeling back one "half" at a time, use a stick adhesive 
(UHU is one common brand) to fasten the paper TO the perfboard 
(Actually, I used to do it all in one shot, with spray adhesive (3m77 
or 90) first, but if you're not used to doing that type of "gotta get 
it right the first time", it will be easier to do one half at a time)

However you do it, you now have "guide holes" for your bit. Just 
drill carefully the first time, and/or punch through the desired 
locations with a pin, resistor lead, etc.

Depending upon th eperfboard you use, there may be some "slop" 
because cheap perf board has relatively big holes. The holes you need 
to drill which are BIGGER than the perf board holes will be "created" 
by the first use of this "drill jig".

I used this method awhile back to do some limited "production" runs 
of boards, and it worked extremely well. I DID still have the etched 
central "dot" which helps reduce the slop effect for samll holes.

Drilling PCB's by hand is all about feel, and with a good "feel", you 
can use the described drill jig to get an .042 hole over your desired 
hole location VERY quickly, and then let the centering depression 
etched into the board do the rest... More importantly, you'll NEVER 
have MORE than the perf board error in any of your drilling...

Hope this helps,

Ballendo

P.S. I used perf board larger than my desired board, and set up 
a "sandwich" with:

1) a lower "exit" board--which has "fences" to "corral" the target PCB
(these are just scraps of PCB material the same thickness as your 
target board) Be sure to leave spaces between these fence pieces so 
that drill swarf can be EASILY blown out after each board is drilled

2) the undrilled but etched target board

3) the perfboard drill jig

I used mylar as a "hinge" to allow target board insertion and removal.

The syatem overall was fast, accurate, and simple enough to set uyp 
to be worth doing--IMO--for "runs" of boards as small as 5 or ten.