Homebrew PCBs

--- In Homebrew_PCBs@yahoogroups.com, "alan00463" <alan00463@y...> 
wrote: Will an inkjet printer make white?

Not any I've had here. :(

After getting a laser for PCB's, I'm finally realizing how much I 
hated the inks. Even if I'm stuck to B&W, not having to constantly run 
out of ink is well worth the loss.

I think the TRF is the safest way to go. It's only about 6 or 7 bucks 
a roll. If they haven't already popped in, someone in here answered a 
few questions for me a while back about it. They said it was more 
powdery, so it wasn't ideal for dual duty as a replacement for the 
green trace coating TRF, but should make good labels. Sorry I can't 
recall exactly who told me (I always appreciate the help).

BTW- With the cutting, I've learned to go oversize on the initial 
boards. I usually do almost an eighth inch all around with some layout 
lines for subsequent trimming. I've had most of my trouble with 
foolishly placing thin runs near the edges. I either eat too close to 
them while trimming, or the board is of a slightly inconsistent 
thickness near the copper burrs at the edge, and doesn't take as solid 
of a transfer. It's also nice to have plenty of space around your 
mounting or standoff holes, to avoid having screws sitting on, or 
shorting anything, or not having enough board at the outside corners.

I've done scroll saw, and "score & snap" with utility knives and glass 
cutters on boards with a few different substrates. It all works, but 
lately I'll just clamp the board down to my workbench, under a wide 
flat block of wood, with the edge hanging off the table. I then saw my 
line with a hacksaw, or even a raw hacksaw blade, taking really light 
strokes at a fairly small angle. This seems to keep the cut line 
straighter, and minimizes some of the blade/board wiggle. As I near 
the end of the cut, I'll raise it more perpendicular, to avoid wasting 
board and cutting way beyond my stop point. I usually cut more on a 
downstroke, and try not to press too hard. I think when I start the 
cuts, I even do only downstrokes until the blade is stable. The board 
wiggle and binding of the teeth in reverse is the main trouble, 
especially with part of the board unsupported. Other than that, the 
whole thing only takes a few minutes, and I've had to cut much harder 
and messier materials in the past. I've got a tile saw here, and 
diamond wheels for my radial, but it probably isn't worth the setup 
hassle, unless I had to produce a whole sheet of boards (unlikely). 
I'm not sure how the cutoff wheels do on a dry run. It's more of a 
smooth "burning" action, which is great with the water, but it may not 
be too safe without it. I had to wear a "leaf bag apron" for cutting 
tile, and it sprays crap all over the place. My tile rig's blade also 
sits at a fixed height, so with thin softer material like boards, it 
seems you'd be even more likely to bind or screw something up, as 
you'd be passing much more blade area. Could be different with the 
fully coated wheel, but my saws will kill you for that.

I usually do my final trimming to the border lines with a belt sander 
running parallel to the board edge, and then stroke a file downward 
across them, at a shallow angle, to clean the copper burrs and level 
the edges. A sander will eat board surprisingly fast, but they both 
sort of work on each other simultaneously, so you're best to use an 
old belt and not expect it to be much good afterward. I've also had 
decent success just laying a full piece of coarse or medium sandpaper 
on a heavy, flat board or bench, and just "slicing" the PCB 
perpendicular across it, back and forth, as if trying to score or saw 
the paper. Just keep your lines moving across the paper throughout, so 
you'll usually have clean grit to work with. This does pretty well 
when there's less board to remove, and I'll also do it with fine 
paper, after the belt sometimes, to smooth or square the edges.

Hope some of that helps,

George