In article ,
Gnube wrote:
I always start with hammer off. If you hit mortar (particularly
lime mortar) with SDS hammer on, you end up with a hole 3 times
broader and 10 times deeper than you intended in less than a
millisecond ;-)

Also, I've had the occasional soft brick which drills fine without
hammer, but shatters to a thousand pieces if an SDS hammer drill
bit touches it.

Actually, you've just made me wonder if on buying an SDS, might it be
better off using the old hammer first, and switch to SDS when the
going gets too tough for it. The thought I'm having is that you'd get
it started gentler and possibly more accurate based on your comment
above, and presumably conserve the life of both tools a little better
too. Granted it'd be a bit more messing about to do it though.

An SDS drill won't engage the 'hammer' action without pressure. So if
you're unsure how hard the masonry is, start with gentle pressure. If the
drill goes in as it will in soft material it won't damage anything.

--
*I used up all my sick days so I called in dead

Dave Plowman London SW 12
RIP Acorn