Homebrew PCBs

>The drawbacks of mechanical etching is that the bits are
>expensive ($6-10 each) and wear out after approximately
>500-1000 linear inches of mechanical etching.  As usual,
>there are no plated through holes, but that is fairly
>typical of the Home Brew PCB crowd.
>
>  
>

  While I wouldn't generally go mechanical for other reasons, I still 
haven't figured why the economy of a real engraving spindle hasn't 
caught on for this.  Low end versions are $100-$150 ish, and several of 
Hermes' themselves are only $250 ish, and the floating versions already 
have float built in..  The 1/4" diamond tip engraving cutters can be 
gotten for $15 or a bit more, and outlast the metal cutters by a good 
margin.  Plus they have a single flat on the shaft for a single cutting 
edge, resharpening is simply a matter of regrinding the flat, although 
I've done that with metal cutters only may not be as easy to do a 
diamond one well.  Diamond tip lasts a lot longer than metal for 
engraving, so while the up front purchase costs are there, it'd easily 
surpass what most people are using in pretty short order.
  OTOH, I do get the impression most people doing it mechanically are 
only making the rare board, so cost and efficiency may not be a prime 
concern really..

Alan