RadioBanter - View Single Post

October 28th 04, 06:42 PM

(Len Over 21) wrote in message ...

Sweetums blurted out:

I use a combination of PDFs, BMPs (via MS Paint) to get 1:1
drill guides for PCBs and small chassis structures.

Welp, I knew there had to be somebody far enough behind the curve to
still be using goofy old MS Paint. For *anything*.

Congratulations Sweetums, you win the annual Kill Bill Society "Last
of the Mohicans" award for 2004.

With either
Corel or Adobe photo edit programs you will find that one can
do quite-exact photo reductions of 2:1 or even 3:1 by the
adjustment of pixels per inch in either Corel Photo House or
Adobe PhotoDeluxe 3. Other photo programs should be able to
do the same thing. Good for one-of-a-kind projects.

I've regularly done 2:1 scale manual PCB resist traces on a pad
of vellum (gridded 0.1"), scanned that into BMP format, cleaned
it up in MS Paint (image attributes set to B&W), dropped the
scale to 1:1, and done the etch masks on VueGraph transparent
stock. Note: Paint allows adding lettering, numbers, etc. as you
need. All without going out to any photo services. Again, good
for quick one-of-a-kind projects.

*GROAN*! I don't believe it, whatta bass-ackward, contorted heap of
nonsense.

And you're an "engineering professional" eh? As if.

Now let me explain the right way to do quickie one-off PCB and panel
layouts Sweetums: In the first place you don't use frigging bit maps
or any of the others of it's pixel-juggling junk for engineering work,
those are for touching up photos of Aunt Minnie's birthday party.

Real profesionals use vector-based graphics software which are
designed for engineering purposes. They're called CAD programs you
see. $100 at any decent computer store gets you 2-D TurboCAD which is
accurate to a millionth of an inch if one cares to get that anal about
locating holes in PCBs and it goes uphill from there. Or even better
dig up Felixcad LT which is a general purpose full-featured freeware
2D CAD program and dump it in.

I'll put it this way: By the time you've fiddled with your pencil,
graph paper, scanner and collection of low-res dimensionally raunchy
photo editing software just to get a drilling pattern I'll have a
complete board layout including all the traces, lettering, donuts and
the drilling pattern done 100% onscreen with a single program. All I
have to do from there is load a sheet of vellum into the old LaserJet,
specify the scale (100:1? No sweat.) and hit the "print" button. Or
print just the hole pattern. Or just the traces and such for board
burning purposes, etc.

Just for the hell of it I checked a couple of my layouts for
dimensional errors with a Pratt & Whitney optical comparator set to
10:1 magnification and the worst error I could find was 0.003 inches
over a six inch span. Which is better than the advertised limit of the
printer accuracy. Try that with Paint.

w3rv