Homebrew PCBs

Well, I finally broke down and bought one of these on sale from 
Staples  ($65 + tax).  

Overall, I like it but it did take some getting used to and its far 
from perfect.

First off, I tried the unmodified laminator with some 32 mil boards.  
It worked fairly well and took about 8 passes through to get 
sufficient toner adhesion.  Basically, one needs to get the board hot 
enough to fuse the toner and that's why so many passes.  The trick is 
to keep the board in laminator as much as possible - as soon as its 
out, feed it right back in the front.  I got pretty good at telling 
when the proper temperature had been reached (i.e. enough passes had 
been made) by touching the board with my fingers.  You also want to 
feed the wider edge of the board to increase the heating area per 
pass.   I trim my paper to have about a 2" border around the board.

I really prefer the 64 mil boards (structurally more sound) so I went 
ahead and make the mods as described on the pulsar site.  The 
instructions are pretty good but I'd suggest reading them carefully 
before opening the case up and once you have the motor/roller 
assembly out, re-read them.  The instructions would be really great 
if there were pictures.   The hardest part is changing the motor 
mount and gearing - the pulsar doc does it in two seperate steps but 
I found it easier to do it as one step.

So I got it back together and fired it up.  There was a clunk when I 
turned it on but it seemed to feed paper ok so I put in a test 64 mil 
board.  It feeds a board ok but makes another clunk when the board 
exits the rollers (as they snap together, I assume).  You can see the 
board jump forward about 1/4" when this happens.  At least there is a 
lot of pressure on the board/paper assembly

I found that when feeding 64 mil stuff, you really need to make a 
*lot* of passes.  20 seems to work ok.  I did a number of boards, the 
largest being 6" x 2.75".  The results are pretty good - nicely 
uniform adhesion and reasonably clean traces.

My biggest issue is alignment of the toner pattern for double sided 
boards.  The pinch rollers tend to pull the top paper so I had to 
resort to using an iron to tack the paper onto the board before 
feeding it.

So, is it better than ironing?  Yes but not as much as I would have 
thought.  The results are more uniform than ironing, especially for 
larger boards.  For smaller ones (2"x3" or so), an iron will produce 
similar results.  People who are making small boards won't benefit as 
much.  Also, given the number of passes you have to make, ironing is 
a little faster.  Another issue I found is that you need to let the 
device warm up even after the light comes on.  If you feed a board as 
soon as the light comes on, about halfway through the light will go 
off indicating that the board cooled off the heater.  I let it warm 
up about 5 minutes more.  Overall, ironing is faster.

One thing I am thinking about doing is figuring out how to slow the 
feed motor to expose the board to more heat for a longer time.  The 
objective is to do the board in a single pass.  Anyone done that?

Phil