On Sat, 18 Jun 2011 14:31:59 +0100, Bert Coules wrote:

In the past, drilling holes through the wall has always resulted in the
inner surface breaking away, sometimes quite extensively,

Function of an SDS when it break through if you are pushing the
drill, think about how an SDS drill works... Once you get close to
full depth stop pushing and take it easy, no gurantee that you won't
get some spalling but it shoud be much reduced.

--
Cheers
Dave.