On Fri, 18 May 2007 19:01:26 +0100, (A.Lee) mused:

The Medway Handyman wrote:

A.Lee wrote:
I've got a line of old concrete posts ...
Trouble is, I cannot drill into these posts to screw in the cross
battens. Invariably I get in half inch or so, hit a stone, then the
drill rapdily goes blunt, and goes no further.
SDS drill with diamond bit?

SDS with a normal masonry bit. Done it loads of times.

No being picky, but why is a SDS drill with a normal masonry bit, better
than a normal hammer drill with the same bit?
Vibrates/hammers more, or something else?

Basically SDS drills use a more efficient hammering mechanism. The end
of the bit is directly struck whereas a normal percussion drill just
sort of rattles the chuck around a bit, really reall lossy way of
transferring energy.
--
Regards,
Stuart.