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John Rumm wrote:

Barry Smith wrote:

You can also get core bits from about 25mm...

But unless I'm very much mistaken, they won't drill through a cavity
wall :-)

What gave you that idea?

I thought the length of a core bit was approximately the same as its
diameter. I will Google for longer core bits.

I have drilled through a cavity wall many times with a core bit. If you
go for a 6" long core then it is already engaged on the second leaf long
before it has emerged from the first. Alternatively you drill a 8mm
pilot right through and then drill the core from both sides.

I'd prefer to drill fully from inside as the outside is approx 20ft
off the ground. I'll be taking it gently so as to (try and) create a
"clean" hole where it exits.

I've seen a 24mm x 1m SDS bit at a local (farmers) market for £5.
I'm guessing it will be ok for a small number of holes. I know it's
long, but drilling a 12mm pilot should guide it.

That being the case I'm now seriously considering buying a drill.
My existing hammer drill, a Bosch CSB 450-2E must be 20 years old? and
has never missed a beat.

I'm tempted by the Bosch GBH 2-23 DRE.

Barry
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