Homebrew PCBs

William Kroyer wrote:
>   This may seem like a silly and basic question but, I've got a bunch of 
> 36"X48" sheets
> of FR4 that I need to cut down.  Nothing I've tried seems to work.  At 
> least not for long.
> Initially, I tried just using my jig saw with a metal cutting blade on 
> it.  I went through 2
> and only got about 1/4" out of each.  Then I tried just using my 
> router.  I killed the bit
> but was able to cut up 1.5 sheets before doing so.  Today I picked up 
> some 7" cut-off
> wheels for my circular saw.  Each wheel cut about 24" each before 
> tearing itself free
> of the mount.
> 
>   Any suggestions? I know for smaller pieces I could probably use a 
> paper cutter as a
> cutting shear but I don't know I'm going to get these large pieces cut down.

I think the easiest way to cut straight lines is to use a scoring 
knife that cuts through the copper and knick the fiberglass enough 
that if you pull a few strokes on each side (must be fairly accurately 
matched, so clamp a straight edge to the material, first), you can 
break the board over a corner with minimal damage.  Then you slide the 
edges over silicon carbide paper to remove the short glass fibers that 
hang out of the break.  I steel cutter won't last very long, but since 
they are easy to sharpen it isn't so bad.  There are also carbide tip 
versions, but I haven't actually used one, yet.
http://www.abc.net.au/sydney/stories/s790713.htm
http://www.epinions.com/Stanley_Scoring_Knife_Shop_Tools
http://www.store.yahoo.com/olfablades/5012.html