If using a core drill, why not drill from the inside out?

'cause a) I'm nervous about the last bits of brick etc. hitting our
downstair's neighbour's window, which is directly under the hole and b) I
need to core a slightly bigger hole on the outside to take the lip of the
access bend.


drill for a core much bigger than 4", my 780W Makita SDS only just coped
with that.

Think I've got the same drill as you - HR2450? Great piece of kit -
definitely my best buy last year :-). So far, this year's best buy is a £4
angle grinder from ScrewFix - £4 'a tells ya!!! Anyway, not planning on
abusing my drill with this job - I think the local hire shop do a proper
core drill with bits for £20 or so.


In think in your case I would be tempted to core bore a hole big enough
for the pipe (say 120mm), and then open out the final couple of inches a
bit wider to accept the elbow using a SDS chisel, rather than make the
whole length of the hole bigger than you need just so the coller of the
elbow will fit one end.

Yeah - I'll either be doing that or, if possible, I'll use two separate core
drills - using the larger from outside to cut a 1-2" rebate into the
brickwork as mentioned.

Andy