asalcedo wrote:
I need to drill a 105 mm diameter hole in a masonry wall 300 mm thick.
It is for the installation of a Miele vented dryer.
All I have is a 750W Bosch SDS Plus drill and some long enough drill
bits
You have few options really.....
Core drill will give you the neatest hole. Alternatively you could chain
drill a ring of holes with a small SDS bit, and then chop out with a SDS
chisel.
I guess I need one of these:
http://tinyurl.com/yvfp9d
and one of these:
http://tinyurl.com/2ckkbt
You may find one cheaper on eBay. Depending on how hard your bricks are
you may need to look at a diamond core rather than a TCT one.
I have a 20mm drill already, can I use it as a pilot drill?
Probably not - the pilot drill usually needs a tapered shank to fit into
the arbour.
Also, what tips and advice do I need to take into account?
Drill a hole right through the wall with a small SDS bit first - that
saves the pilot bit having to cut at the same time which will slow you
down quite a bit. Once you have started the core and have sunk it to a
couple of cm you can remove the pilot drill - you wont need it any more
and it may increase the possibility of snagging.
Take it slow and don't push too hard on the core drill - your 750W drill
is a tad on the small size for this job really (I have cut similar cores
with my 780W SDS - and it only just hacks it since you are right on the
threshold where the clutch will slip).
When starting the whole you can "orbit" the body of the drill a little
such that you cut the core a little wider to start with. Once you are
into the core keep it straight and level.
Be prepared for the drill to snag - the clutch on the machine should let
go before you get your wrist twisted off, but take care just the same -
don't keep anything too delicate in the path of the side or back handles
should they decide to go for a spin!
How do you break the core? With a hammer and chisel?
Stick a SDS chisel in the drill...
If you are cutting through a cavity wall, then chances are you won't
need to - the core bit is usually deep enough to go through a whole brick.
--
Cheers,
John.
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