>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