Hi, I need to install an extractor fan.

Instead of using a drill bit to drill multiple holes around the
circumference and then chistle knocking out the brick, is there a tool
available for hire or buy (if cheap) to drill the hole neatly and in
one shot?

Ta

On 4 Aug, 15:27, Dundonald wrote:
Hi, I need to install an extractor fan.

Instead of using a drill bit to drill multiple holes around the
circumference and then chistle knocking out the brick, is there a tool
available for hire or buy (if cheap) to drill the hole neatly and in
one shot?

Yes, you want a core drill. Usually a diamond grot drillbit, but some
are just carbide. Some are wet, some are dry. Or you can buy a set: 40
quid from Aldi quite recently.

You'll also want to hire the appropriate slow-speed high-torque drill
to drive it, with a long sidehandle to brace yourself with and a
safety clutch to avoid snatching and throwing you off the ladder.
Don't use a normal drill. Certainly don't use hammer action!

Mostly they begin from a pre-drilled pilot hole, so you'll want an SDS
drill for doing that first (If you need to fix houses, you need to own
one of these anyway).

Andy Dingley wrote:
On 4 Aug, 15:27, Dundonald wrote:
Hi, I need to install an extractor fan.

Instead of using a drill bit to drill multiple holes around the
circumference and then chistle knocking out the brick, is there a tool
available for hire or buy (if cheap) to drill the hole neatly and in
one shot?

Yes, you want a core drill.

They are quite expensive to buy or hire; TBH for a one-off I would just
do the chain-drilling method you've described, if you have an SDS drill.
I've fitted quite a few myself and have never felt the need to bother
with a core drill.

Because you always have a grille of some form at both sides of the wall,
any slightly ragged edges to the hole will be hidden from view anyway.

David

In message , Lobster
writes
They are quite expensive to buy or hire; TBH for a one-off I would just
do the chain-drilling method you've described, if you have an SDS
drill. I've fitted quite a few myself and have never felt the need to
bother with a core drill.

Once you have used a decent core bit and drill you will never want to go
back, much easier and neater.

Because you always have a grille of some form at both sides of the
wall, any slightly ragged edges to the hole will be hidden from view
anyway.

But YOU will know it's not neat and tidy, how can you live with that?
:-)

David

--
Bill

In an earlier contribution to this discussion,
Lobster wrote:

Andy Dingley wrote:
On 4 Aug, 15:27, Dundonald wrote:
Hi, I need to install an extractor fan.

Instead of using a drill bit to drill multiple holes around the
circumference and then chistle knocking out the brick, is there a
tool available for hire or buy (if cheap) to drill the hole neatly
and in one shot?

Yes, you want a core drill.

They are quite expensive to buy or hire; TBH for a one-off I would
just do the chain-drilling method you've described, if you have an
SDS drill. I've fitted quite a few myself and have never felt the
need to bother with a core drill.

Because you always have a grille of some form at both sides of the
wall, any slightly ragged edges to the hole will be hidden from view
anyway.
David

I recently needed to drill an 110mm hole for a tumbler drier outlet -
admittedly near ground level, so no ladders involved. I managed to buy a
suitable brand new core drill from a car boot sale for a tenner - ok it was
TCT rather than diamond and a bit slow. By first drilling a pilot right
through, and then using the core drill to go halfway (into the cavity) [1]
from both sides, I ended up with a nice neat hole.

[1] It went through the block on the inside like cheese, but made harder
work of the brick - so I only went a little way into the brick and then
finished off with a ring of holes and a chisel - but the visible hole was
still perfectly round.

--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

If the hole 120mm, bricks are not hard, not done above head height...
- Go to Amazon UK
- Buy 110-120mm diamond core drill & arbor for £18+5
- Use any 450W non-hammer drill, tape hammer action off
- Go /very/ slow /without/ force - let the diamonds do the cutting
- Let the drill cool off regularly - low RPM means low motor cooling

The core should be perfectly round or return it.

If the hole is larger, bricks are hard, done on a ladder...
- Hire a tower, not a ladder or do from inside (dust is invasive)
- Hire a diamond core drill with clutch & pro core drill

The clutch means when the core jams you don't break your wrist.

TCT bits require hammer action, are slow, very noisy, often not long
life and are pretty pointless when you can pick up perfectly good
diamond core drills for under £20.

Sintered diamond core drills (long tabs) work very well and have a
long life. However if you hear screeching or get a lot of chatter your
bricks are hard and you need a proper hire tool (very high torque
drill with clutch, heavy duty core).

Make sure you do not have a hidden engineering brick, hitting one of
those can rip the tab off a sintered diamond core drill although the
bit will shriek & chatter violently. Very hard bricks can take hours
to get through even with pro tools, I've still no idea what gets
through my bullnose quarry tiles which cause any diamond tool to
shriek without making any impression at all.

Wide diamond core drills have a "stable square stance" which helps
when drilling (remove pilot once hole is started) and the very low RPM
(80-90rpm for 120mm) means they are not too difficult to work with.
Slow is key, the tool does everything with very little pressure. Do
not get bored and try high RPM (just invites a chatter & seize in the
hole, risking a broken core drill tab or worse your wrist). Be
prepared for the amount of dust, which is actually more like custard
powder.