Jan,
The Dremel only costs $59 verses your $400 solution. Please
note this is the Homebrew PCB conference. Cost is everything! It
may be possible to find a surplus dentist drill. I find the Dremel
tool does a great job! I sell the boards I make with mine.
John
--- In Homebrew_PCBs@y..., JanRwl@A... wrote:
> In a message dated 26-May-02 06:09:15 Central Daylight Time,
> john@k... writes:
>
>
> > The problem with Mechanical Etching is the epoxy in the board.
>
> Correction, if I dare: The "epoxy" is merely easy-to-cut "plastic
stuff"!
> It is the GLASS FIBER impregnated in the "epoxy" which eats up
cutting-edges!
>
>
> I suspect the main reason alternatives of pointed "engraving" bits
is
> considered here is that such a TINY portion of tool is "in the
work" at any
> instant, it therefore has to TURN at such a tremendous speed to
have any
> suitable "surface-speed" to work, at all, whereas the CIRCUMFERENCE
of even a
> 1/8" dia. bit would have much more surface-speed, even at slower
RPM. That's
> why a modern dental hand-piece turns those tiny "burrs" (mill-
bits!) at
> 100,000-300,000 RPM and more!). Tip: Dentists typically throw-out
used
> burrs, even if only "package opened, but not actually used". Next
time you
> have 3 grams of amalgam put in your face, ask the dentist if you
can HAVE
> "your" used burrs (you HAVE paid for them, after all!). These will
> (usually?) have 0.0625" dia. shanks, yes, even those built-in and
USED-in the
> rest of the world, I think! So, you will have to use the correct
collet,
> etc. But those can probably do "mechanical PCB etching" very well,
if turned
> at least 30,000 rpm or more. Think AIR-MOTORS!!! Whew, even if
the "main
> spindle-bearing" were dual-race angular contact ball-bearing,
a "Dremel tool"
> just isn't the kind of "quill motor" for a PCB drill!
>
>
> [Non-text portions of this message have been removed]