Homebrew PCBs

>I can do 12/12 mil tracks, with 10 mils if necessary, using an old LaserJet
>IIIp to produce the transparencies. I was wondering what is the best any of
>you can do with a laser printer. I've heard of people getting down to 8 mils
>with a better printer than mine, and it should be quite easy using
>photo-reduction from a 4:1 master.

Leon,

I can do 8 mil - no problem - by directly printing onto transparency
paper (not using photo-reduction or such) using an older HP LaserJet
4P. This laser is having a 600 dpi resolution. I'm sure I could go
even finer since text that I print with a very small font even ends up
readable but so far never had the need for finer pitch artwork.

I either must be very lucky, or then other factors like the base
material and it's photosensitive layer, kind of transparency paper I
use, developper or etching may are also important. What surprizes me a
bit is to hear how much sucess in this area varies among people. Some
people only seem to get average results even if they use
professionally made photo films while others like me can do well with
just cheap transparency paper.

Markus