On Tue, 13 Jul 2010 10:52:50 -0500, Ignoramus3537
wrote:

My guess is that it is for people who want to drill large holes.

i
And I thought that the 1948 US Electrical Tools 1/2 drill I bought the
other day would be a poor choice to use for drilling joists in a house
wiring project!
Gerry :-)}
London, Canada