Hi Jan,
yes, the box of 50 solid carbid, 'reconditioned' bits in various
sizes.
My Old Scott nameplate engraver uses a half flute single edge for
cutting and for milling, that seems like the simplest way. and you
can do that by hand if you have a diamond wheel.
The mechanics about what you pointed out is that the fiberglass does
not creat chips and leave the cutting zone, it powders and eats away
at soft stuff in the area. I have had to drill cindeblock on
occasion and used standard HSS drills. probably lasted about as long
as HSS in PC boards.
With my limtied metal working experiance, I have firmly come to the
conclusion that you 'can' do the impossible, but it takes time and
effort. you 'can' regrind after every few holes or just buy the
correct bits in the firstplace.
I too have a box full of punches and scribes made of broken tooling.
can't beat good carbide for putting your mark on parts.
I was wondering how well these reconditioned bits work ? why they are
sooo cheap ? are they undersized ? bad units? factory rejects? how
can so many people sell them ? maybe it is a PCB factory waste
product from the far east. Sombody has to make all the PCBs for our
TV's and Radio's.
Dave
--- In Homebrew_PCBs@yahoogroups.com, JanRwl@A... wrote:
> In a message dated 1/12/2003 12:39:07 PM Central Standard Time,
> dave_mucha@y... 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
>
>
>
>
>
>
>
>
> [Non-text portions of this message have been removed]