Homebrew PCBs

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]