Breaking Bits

[abknight@zzzzzz]

I bought a new air-powered
rock drill from Airdraulic
Birco in Brisbane,
it's the equivalent of the CP9
rock drill. Previously, I had
been using
hollow drill bits and they
were breaking like matchsticks
(well nearly)
at $170 each. So I got some
K-taper adaptors for the three
rock drills
and the Hilti TE42 that we
use, and some solid K-taper
masonry bits
 from ADBirco. Haven't broken
any of them so far - and they
are less
than 1/3 the price of the
Atlas Copco hollow bits.

Simon,

I broke three bits in very short order.  The last one inch
or so would just twist off, right about at the blow holes.
Is that where yours broke?  They were off brand drills. I
now have an Atlas or Vulcan but have lost all confidence
in drilling! (cp9)  The off-brand vendor thought the
breaks were very odd.  I returned them for a "Rockwell"
metal test but the US mail ate the box.  The sellers of
the name bits of course blamed the inferior off brand
bits.  I am discouraged to hear of your Atlas bits
breaking.

A solid bit would not remove debris from a deep hole.  Do
you use a blower?

I've talked to an experienced granite carver who said a
great deal of "touch" was required when drilling and that
his apprentices broke bits all the time from "pushing them
too hard".  I have little sense of this as I try to push
just hard enough to make them chew and didn't think I was
doing anything out of line when tips broke off.

Bill