Homebrew PCBs

>Curt controlled his spark discharge voltage by
>dynamically adjusting the electrode gap on the fly. I
>think that for pcb work this is not the correct
>approach because of the wire erosion problem, since
>one needs to KNOW the gap distance AND available
>discharge energy BEFORE discharge, which is why I am
>going for the touch down zeroing method, (slower but
>speed is not significant at the moment). The discharge
>  
>


  Don't you want to try changing every other variable first, to see if  
you can eliminate the erosion problem first, then adjust everything else 
to match?  With the same distance everything else could be just as well 
known with 1/4 the spark energy and 4x the rate for the same total, 
seems you could simply be too close for the instantanious spark energy 
you are using or something similar..
  Only messed with EDM a few times, but I think I'd try everything under 
the sun first before living with the electrode eating up, even to the 
point of feeding blasting caps to the goats in the backyard before 
giving up.. Keep them away from the back wall unless you want a mess.  
And keep a camera handy, you will want a pic of the PETA girl's face.


  Also start thinking now about two electrodes.  Could cut both sides 
with a 2 tooth tip, but independent control would be better.  Raise one 
while traveling to make an intersection.  Change the width for different 
traces or pads etc.  And start routing everything with parallel traces 
and you'll be cutting one edge of two traces at once, should cut the EDM 
time about in half.  Might even be nice for a third or fourth parallel 
electrode for use while the board is already under control..

Alan