Homebrew PCBs

I modified an old CNC training machine to work with DeskCNC and have 
been happily 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  http://www.northbaytechnical.com/ . These bits work great but 
are a bit spendy at about US $15.00 each. Does anyone have 
suggestions/different suppliers etc they can recommend? I don't think 
self sharpening works too well for me as the bits are just too darn 
small and brittle. BTW the size of track you can get down to with 
these bits seems to be 8 thou or smaller, pretty impressive I think.

Hi,
   I use the 60 degree mechanical etching bits from Think and Tinker. 
They are about $9US each in lots of 10. I have yet to try a CARBIDE 
dental bit. See if you can locate one. Make sure it is CARBIDE! The 
HHS ones do about 12" and then die. What RPMs and speed are you using?

                                              John 


--- In Homebrew_PCBs@yahoogroups.com, "aussiedude36" 
<aussiedude@e...> wrote:
> I modified an old CNC training machine to work with DeskCNC and 
have 
> been happily 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  http://www.northbaytechnical.com/ . These bits work great but 
> are a bit spendy at about US $15.00 each. Does anyone have 
> suggestions/different suppliers etc they can recommend? I don't 
think 

> self sharpening works too well for me as the bits are just too darn 
> small and brittle. BTW the size of track you can get down to with 
> these bits seems to be 8 thou or smaller, pretty impressive I think.

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


[Non-text portions of this message have been removed]

I've never tried this, but here's some info:

http://www.angelfire.com/az2/proff/PaulJonesEngravingCutters.html

Grant

--- In Homebrew_PCBs@yahoogroups.com, "aussiedude36" <aussiedude@e...>
wrote: 
> Does anyone have 
> suggestions/different suppliers etc they can recommend?