# how do you drill a large hole in brick for air con?



## AndrewBaker (27 Aug 2013)

Hello

the hole will need to be about 150mm in diameter

what drill should I buy and what bit?

thanks!


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## paul saunders (27 Aug 2013)

A hand brace and a 150mm core drill .................. should keep you busy for a while :lol:

On a serious note, any good quality drill and a 150mm core drill. Or if you want to you can hire them from any good tool hire shop.


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## John15 (27 Aug 2013)

Hi Andrew,
150mm dia is quite a big hole to drill in one hit - I've seen it done many times with diamond core bits for services etc on construction jobs, but for a one off I imagine it would be expensive. Maybe a more economical way would be to stitch drill with a smaller masonry bit, say 1/2" dia.
Regards,
John


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## longinthetooth (27 Aug 2013)

Diamond core drill, hire it with a big drill that has a safety clutch so it doesn't rip your arm off when it the bit snatches ... and have lots of porridge for breakfast first. 

What's air-con for, can't you just open a window?


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## Sheffield Tony (27 Aug 2013)

I have tried it both ways; the core dril was neat but slow, the chain drilling approach quick but a bit ragged. If you go down the core drill route and hire the bit, make sure it is not too worn - the diamond loaded teeth should be about 2.5-3 mm thick. If they are worn much thinner, the body of the drill following them will bind in the cut, getting worse as it heats up and expands. Painful experience here ...


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## ColeyS1 (27 Aug 2013)

Its really not as bad as it seems. 

Sent from my GT-I9300


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## Hivenhoe (27 Aug 2013)

Lidl or Aldi were selling core bits not too long ago, they may not be the best but worth a look as they will be cheaper than the hire even if you throw them when done and don't be tempted to use hammer action to hurry things up.


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## Jacob (27 Aug 2013)

Cheap core bits are PITA as we discovered recently (in hard limestone). A top notch bit (Macrist etc) will sail through it and pay for itself in no time.


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## Plumberpete (28 Aug 2013)

Get yourself down to your local toolhire place. It'll cost you around £20 to hire the right size drill and core-drill bit for the day.


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## AndyT (28 Aug 2013)

At risk of stating the obvious this is easier if your wall is solid. If it is a cavity wall you need to avoid dropping bits into the cavity or bursting lumps off the internal back surface of the first leaf.


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## Andy RV (28 Aug 2013)

When using a core drill should you drill from both sides to avoid blowing out the brick / plaster face when you break through?


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## WandrinAndy (29 Aug 2013)

As an alternative to drilling, have you given a thought to using a brick chisel/bolster and then filling the excess afterwards?


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## RogerS (1 Sep 2013)

AndyT":2s2hasjr said:


> At risk of stating the obvious this is easier if your wall is solid. If it is a cavity wall you need to avoid dropping bits into the cavity or bursting lumps off the internal back surface of the first leaf.



That reminds me of a slight faux pas a couple of years back. I was putting in an extra window and thought I'd do a little investigation first as to the wall construction. Dry-lined internally, I was curious as to how thick the wall might be as the house is a mixture of very thick walls, brick and stone. So got the angle grinder out and busily carved away some mortar around one of the bricks from the outside wall. Lots of dust as you'd expect. Finally removed the brick to peer into the cavity. Bit dusty after all the grinding.

Surprised to see faint light inside the cavity. Strange, I thought. Where is that light coming from? Glimmer from the loft down the cavity? But there's no light in the loft...very strange. i peered closer to see some wires or what looked to be like wires. That's even stranger, I thought. I don't remember any wall lights when we first moved her or ever taking them out. 

The dust cleared. The wires came into sharper focus and revealed themselves as our central ceiling light. The wall was not cavity...the hollow sound I'd thought was a dry-liner was the cement render/plaster coat having detached itself from the wall. The wall was single skinned. The dust and debris from removing the brick lay on the settee. A fine layer of dust starting to settle on the TV, the books, the hi-fi.

I heard my wife arrive back with the shopping ........................................


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## Graham Orm (1 Sep 2013)

Hire a core drill, and machine. As said above make sure the drill is NEW! They will charge you for wear so may as well ask for brand new as worn. Despite the instructions telling you NOT to use SDS hammer action if you can it speeds up the process dramatically. OK you wear the drill bit out in 2 holes instead of 6, but having done many I always go for the quick option.
It's hard work and will leave you aching, make sure you have a comfortable footing.
If you can, drill right through with a long pilot bit first then drill from both sides to avoid bursting the brick on the outside when you break through.


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## Hitch (1 Sep 2013)

Drill through with a long sds bit first, then use a diamond core drill from both sides.


Hire it, as Jacob said, cheap diamond cores make life hard work.
Unless you have a top notch drill too, hire the drill to go with it, slow and plenty of torque.


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## CaptainCaveman (21 Sep 2013)

If you already have a big drill, go and get a cheapo £30 set from Aldi, not much more than hiring one and you will use it again at some point (or the variety of other sizes that come in the box!).


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