Homebrew PCBs

In a message dated 9/1/2003 1:48:27 PM Central Standard Time, 
john@... writes:

> engraving PCB's for a while now, however the only bit that I have found 
> that works really well is a M99 carbide spade bit from . . .

I simply save busted carbide drill-bits and grind the tips at a very slight 
angle, so that one of the flute-tips is the lowest point, and run those at 
30,000 RPM, with perhaps 150 IPM feed-ratge.  Thus, the cutters are "free", as I 
keep lotsa busted solid-carbide bits!  

You can also grind off ALL the "flute" and make a regular engraver's bit of 
the "cone end" of the 1/8" shank.  This shape is much sturdier than a re-ground 
drill-bit end, of course.  

Jan Rowland


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