Homebrew PCBs

In a message dated 1/12/2003 5:04:39 PM Central Standard Time, 
dave_mucha@... writes:


> 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:  GOOD questions, and ones I think worthy of discussion "here"!  I have 
wondered this myself, and I have had to rely only on my "imagination" for 
answers, as it is not SO earth-shaking a quest that'd I'd "get in the car and 
drive about to the several PC-houses within 50 miles, to inquire"!  

They work very well on MY "CNC" drill, so long as the machine makes NO 
attempt to "move to next hole" before the quill is 100% UP and still.  And, 
for hundreds of holes, it seems, before dull.  Actually, I have never 
"dulled" a carbide bit, yet!  I have also used them in a vertical mill (used 
as "drill-press") to drill HSS with success.  Carbide is AMAZINGLY tough 
stuff!  

The word "recoditioned" merely means "re-sharpened"!  I do NOT think they are 
"bad", "rejects", or "far east waste".  I think they are simply "sold cheap" 
to those who scarf-up such, and re-sharpened, as the PCB-houses probably 
drill almost-ONLY in "stacks", so that re-sharpened bits would be just TOO 
short to be useful for that application.  MY guess.  

Yes, I am GUESSING that the houses that drill those PCB's for "our TV's and 
computers" go through MILLIONS of these bits (ever see a PCB machine drill, 
and CHANGE ITS OWN BITS?  Wizardry!  Four or five holes per second, through 
four STACKS up to 7 boards deep!  100,000 and up RPM air-drills!  So, 
mind-bending as it is, I guess there ARE sources for those "boxes of fifty" I 
have seen offered by, oh, three or four mail-order houses.  Yes.  Whew!

Surely there is SOMEone "in here" who is "professional" or has a sister who's 
husband's cousin works for a PCB-house who can TELL us how far-off I am with 
these guesses???  We'd ALL like to know?

Jan Rowland


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