Re: Machining

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Richard Modistach" <hambone-at-dodo-dot-com.au> 

i use 'second hand' ball nosed dentists drills from my local dentist
at about 3000 rpm (slow speed), they cut through pcb's like a hot knife
through butter, might be blunt for a dentist but still sharp as a razor for
me, and an unlimited supply of all sorts of sizes and shapes at 0 cost.
great for engraving too.
been using them since i made my first pcb when i was about 13yo back in the
early 70s.
used to get my pcb for nothin too, certain black and white valve tv's had a
piece of 8x8" blank pcb as a shield, used to raid them from the dump.

regards
richard
aus

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Tuesday, April 20, 2004 8:28 AM
Subject: Re: Machining


 > Original poster: "Malcolm Watts" <m.j.watts-at-massey.ac.nz>
 >
 > Hi Matthew,
 >
 > On 19 Apr 2004, at 7:23, Tesla list wrote:
 >
 >  > Original poster: Matthew Smith <matt-at-kbc-dot-net.au>
 >  >
 >  > Ed Wingate wrote:
 >  > >Titanium nitride coated tools are worth the extra cost for many
 >  > >applications.
 >  >
 >  > My (limited) experience of drilling G10 PCB stock with a cheap'n'nasty
 >  > drill press (the Aussie equivalent of one a US 'Harbor Freight'
 >  > machine) confirms this.  Although for the sub-1mm holes, I have to use
 >  > carbide bits with an oversized shank, as they are all I can get.  It's
 >  > an expensive job as the play on the chuck causes a lot of breakages.
 >  > 1mm+, I have a set of TiN coated bits.  These are just beau-u-u-tiful
 >  > on PCB stock, cut fast, don't break* and leave good, clean holes.
 >
 > To minimize the chances of breakages when drilling sub-1mm holes in
 > Cu-fibreglass board with W-C drills I put a 1/2" - 1" thick slab of
 > styrofoam on the platform and put the board on top of that.
 >
 > Malcolm
 >
 >  > I would extrapolate this out to be good for RSG rotors of similar
 >  > materials.
 >  >
 >  > Cheers
 >  >
 >  > M
 >  >
 >  > *I had to go and say it, eh?  My next drilling job is doomed ;-)
 >  >
 >  > --
 >  > Matthew Smith
 >  > Kadina Business Consultancy
 >  > South Australia
 >  > http://www.kbc-dot-net.au
 >  >
 >  >
 >  >
 >  >
 >
 >
 >