Homebrew PCBs

> toner transfer.  Only problem with toner transfer is the "scaling" 
> issues either through the printer or from the paper not being 
stable 
> which causes problem with CNC drilling.

If you bave scaling issues - they will exist with a laser or inkjet 
printer.  My inkjet printouts (using corel draw) are so precise, I 
can actually print grids and squares to calibrate my cnc machine.  I 
have printed rulers and checked them with my digital calipers, and 
they are by far - very accurate.  I dont know what software your 
using to create the images, there are a billion options. Simply in 
corel draw, I can create tiny lines and examine them against a 
precision ruler using a 10x magifying lens - matching dead on.

If it is out of scale for toner transfer, then that same image you 
will use for photo-resisting, will also be out of scale.

> The first "problem" I suspect I will run into is getting enough 
> density on the transparency to make sure the "black" areas are 
dense 
> enough to block out the UV exposure lamp where needed.  Has anyone  
> run into this issue and how do you deal with it?

When I attended the seminar on homemade pcb making, there was a large 
variety of people that have had very good success for YEARS doing 
photo-resist etching.  They say it takes about 15 minutes to expose a 
very exact board with SMT leads.  A standard laser printer provides 
enough coverage on a transparency to expose the image.  I was told 
they order the "GC" type boards from DIGIKEY.

Hope this helps a little.