In a message dated 1/12/2003 12:39:07 PM Central Standard Time,
dave_mucha@... writes:
> It seems like the box of 50 burrs from Harbor Freight are the best bang for
> the buck, IF they last.
>
Dave: You didn't mention if these are solid-carbide, diamond-"plated", or
what. Carbide holds up well against such as FR-4 ("glass-epoxy"), Diamond
would "forever", if the diamond were the ONLY material touching the
glass-fibers, but that "diamond plated" stuff is just that: They
nickel-plate diamond-grit onto a HSS spindle, so as soon as the nickel
outer-"skin" is worn off (within first two seconds of use!), there is little
"holding" the diamond bits on the steel. AND, there is plenty of steel
(nickel-plated or not!) exposed to the glass-fibers, between the rather OPEN
grit-area, at the start!
I found out LONG ago that even the "new wholesale" price of solid-carbide
drill-bits (often more than $2.00 per bit!) is cheaper "per hole successfully
drilled" than ANY HSS drill-bits, even if you can resharpen them yourself
(every twenty holes?), and have a "chuck" capable of gripping HSS bits, which
are NOT made with "One Size Fits All" 1/8" dia. shanks as are carbide bits.
A carefully-zealous "browsing shopper" can find BOXES of useful-sizes of
solid-carbide bits offered in the various mail-order catalogs such as JDR
Microdevices and JAMECo, etc. I don't know that their current pricing is
like, but I have bought several boxes of 50 "reconditioned" bits of size #57
or #65, etc., for less than $1.00 per bit! NEVER throw away the 1/8" shank
when the "drill-part" breaks off, as that is VERY useful "tool-making stuff"!
All you need is a little diamond-wheel on a little grinder-motor, some
imagination, and minimal skill!
I do not "machine-etch" PCB's (easier to chemically-etch!!!), but I note
there are many "of us" who do, and I wonder why no one has offered that these
busted, "useless" (NOT!) solid-carbide drill-shanks would be ideal for the
tooling on a machine-etching job! Ya just have to grind an "engraver's tip"
on the pointed-end of the shank (where the drill-part left for a galaxy far,
far away)! True, one must have a nice small lathe (Unimat, Sherline, Taig,
etc.), if not a "bit holding fixture" and a diamond-cup-wheel grinder rig,
and some wisdom and skill. Some may-well know a "machinist-friend" who
grinds his own tooling, who will do these as a favor. Might be a "project"
for some ambitious soul! Others might find some grinding-shop willing to DO
this "for us all" at a reasonable price, mail-order---we just supply the
shanks/blanks. Can someone with more wisdom on this point comment???
Jan Rowland, old troll
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