Hi All,

I'm fitting a 4" extractor fan through a solid block wall.
Rather than faff around with drilling lots of parallel holes, then
attempting to chisel out the middle (as I've done previously), I
decided to lash out and buy a suitable core bit.

It's an SDS TCD core bit, with a smaller guide bit in the middle.
110mm outside diameter.

Should I use hammer+rotate with this bit, or just let it "grind" on
rotate only?

Planning to start on the inside, cut to the 75mm depth the bit allows,
drill through the guide bit hole to find the spot outside, then drill
back in from outside.
If this doesn't join up, and I don't think it will, I'll chisel out
the centre of the cut, and go again.
Does that sound reasonable?

On the inside, the wall has been faced with 50mm insulated dry lining
board, but not yet taped or skimmed.
I'll have to cut through that first before reaching the inside face of
the block.
Any reason not to use the core bit at slow speed and no hammer to make
that cut first?

Any other advice or tips much appreciated on using this bit much
appreciated.


Regards,

bookieb.

b
"bookieb" wrote in message
...
Hi All,

I'm fitting a 4" extractor fan through a solid block wall.
Rather than faff around with drilling lots of parallel holes, then
attempting to chisel out the middle (as I've done previously), I
decided to lash out and buy a suitable core bit.

It's an SDS TCD core bit, with a smaller guide bit in the middle.
110mm outside diameter.

Should I use hammer+rotate with this bit, or just let it "grind" on
rotate only?

Planning to start on the inside, cut to the 75mm depth the bit
allows,
drill through the guide bit hole to find the spot outside, then
drill
back in from outside.
If this doesn't join up, and I don't think it will, I'll chisel out
the centre of the cut, and go again.
Does that sound reasonable?

On the inside, the wall has been faced with 50mm insulated dry
lining
board, but not yet taped or skimmed.
I'll have to cut through that first before reaching the inside face
of
the block.
Any reason not to use the core bit at slow speed and no hammer to
make
that cut first?

Any other advice or tips much appreciated on using this bit much
appreciated.


Regards,

bookieb.

Drill all the way through the wall with an sds drill of the drill
guide diameter, then drill from both sides with the 110mm core drill,
that way you get a neat hole on both sides of the wall that does line
up. If your core drill is diamond impregnated then it just needs to
rotate, but if it has tungsten carbide teeth then it needs to hammer
as well.

AWEM

On Dec 20, 2:06*pm, "Andrew Mawson"
wrote:
b"bookieb" wrote in message

...



Hi All,

I'm fitting a 4" extractor fan through a solid block wall.
Rather than faff around with drilling lots of parallel holes, then
attempting to chisel out the middle (as I've done previously), I
decided to lash out and buy a suitable core bit.

It's an SDS TCD core bit, with a smaller guide bit in the middle.
110mm outside diameter.

Should I use hammer+rotate with this bit, or just let it "grind" on
rotate only?

Planning to start on the inside, cut to the 75mm depth the bit
allows,
drill through the guide bit hole to find the spot outside, then
drill
back in from outside.
If this doesn't join up, and I don't think it will, I'll chisel out
the centre of the cut, and go again.
Does that sound reasonable?

no, drill all the way from one side. Its normally easy to knock the
central masonry plug out once you've drilled around it.


NT

On Dec 20, 2:00*pm, bookieb wrote:
Hi All,

I'm fitting a 4" extractor fan through a solid block wall.
Rather than faff around with drilling lots of parallel holes, then
attempting to chisel out the middle (as I've done previously), I
decided to lash out and buy a suitable core bit.

It's an SDS TCD core bit, with a smaller guide bit in the middle.
110mm outside diameter.

Should I use hammer+rotate with this bit, or just let it "grind" on
rotate only?

Planning to start on the inside, cut to the 75mm depth the bit allows,
drill through the guide bit hole to find the spot outside, then drill
back in from outside.
If this doesn't join up, and I don't think it will, I'll chisel out
the centre of the cut, and go again.
Does that sound reasonable?

On the inside, the wall has been faced with 50mm insulated dry lining
board, but not yet taped or skimmed.
I'll have to cut through that first before reaching the inside face of
the block.
Any reason not to use the core bit at slow speed and no hammer to make
that cut first?

Any other advice or tips much appreciated on using this bit much
appreciated.

Regards,

bookieb.

If you buy the better expensive diamond drill,no hammer action. Some
need water cooling-ask.
TCT needs a hammer action, is not as expensive but usually there is a
breakout hole unless you drill from both sides.

It's very easy for a big drill like this to jam. Take extreme care. it
can break your wrist. Be sure your drill has a safety clutch, some
don't.
Many small SDS drill won't handle it. Ask before you buy.

BTW. You drill as far as it will go and then break out the core and
your can drill some more. You can buy extension pieces for deep holes.

John Rumm wrote:
On 20/12/2010 15:00, Tabby wrote:
On Dec 20, 2:06 pm, "Andrew Mawson"
wrote:
wrote in message

...



Hi All,

I'm fitting a 4" extractor fan through a solid block wall.
Rather than faff around with drilling lots of parallel holes, then
attempting to chisel out the middle (as I've done previously), I
decided to lash out and buy a suitable core bit.

It's an SDS TCD core bit, with a smaller guide bit in the middle.
110mm outside diameter.

Should I use hammer+rotate with this bit, or just let it "grind" on
rotate only?

Planning to start on the inside, cut to the 75mm depth the bit
allows, drill through the guide bit hole to find the spot outside,
then drill back in from outside.
If this doesn't join up, and I don't think it will, I'll chisel out
the centre of the cut, and go again.
Does that sound reasonable?

no, drill all the way from one side. Its normally easy to knock the
central masonry plug out once you've drilled around it.

Depends on how long your arbour is - on thick walls the drill won't
fit through the 4" hole ;-)


It depends how high up on the outside wall the hole is!

--
Adam

Andrew Mawson wrote:
b
"bookieb" wrote in message
...
Hi All,

I'm fitting a 4" extractor fan through a solid block wall.
Rather than faff around with drilling lots of parallel holes, then
attempting to chisel out the middle (as I've done previously), I
decided to lash out and buy a suitable core bit.

It's an SDS TCD core bit, with a smaller guide bit in the middle.
110mm outside diameter.

Should I use hammer+rotate with this bit, or just let it "grind" on
rotate only?

Planning to start on the inside, cut to the 75mm depth the bit
allows, drill through the guide bit hole to find the spot outside,
then drill back in from outside.
If this doesn't join up, and I don't think it will, I'll chisel out
the centre of the cut, and go again.
Does that sound reasonable?

On the inside, the wall has been faced with 50mm insulated dry lining
board, but not yet taped or skimmed.
I'll have to cut through that first before reaching the inside face
of the block.
Any reason not to use the core bit at slow speed and no hammer to
make that cut first?

Any other advice or tips much appreciated on using this bit much
appreciated.


Regards,

bookieb.

Drill all the way through the wall with an sds drill of the drill
guide diameter, then drill from both sides with the 110mm core drill,
that way you get a neat hole on both sides of the wall that does line
up. If your core drill is diamond impregnated then it just needs to
rotate, but if it has tungsten carbide teeth then it needs to hammer
as well.

Errrm. My TCT core drill set says definately no hammer in the destructions
& thats how I've always used it.


--
Dave - The Medway Handyman
www.medwayhandyman.co.uk

On Dec 20, 5:00*pm, John Rumm wrote:
On 20/12/2010 15:00, Tabby wrote:



On Dec 20, 2:06 pm, "Andrew Mawson"
*wrote:
*wrote in message

....

Hi All,

I'm fitting a 4" extractor fan through a solid block wall.
Rather than faff around with drilling lots of parallel holes, then
attempting to chisel out the middle (as I've done previously), I
decided to lash out and buy a suitable core bit.

It's an SDS TCD core bit, with a smaller guide bit in the middle.
110mm outside diameter.

Should I use hammer+rotate with this bit, or just let it "grind" on
rotate only?

Planning to start on the inside, cut to the 75mm depth the bit
allows,
drill through the guide bit hole to find the spot outside, then
drill
back in from outside.
If this doesn't join up, and I don't think it will, I'll chisel out
the centre of the cut, and go again.
Does that sound reasonable?

no, drill all the way from one side. Its normally easy to knock the
central masonry plug out once you've drilled around it.

Depends on how long your arbour is - on thick walls the drill won't fit
through the 4" hole ;-)

I got the extension bit with mine. And the hex shanked arbour as well
- dont try using that unless you have to.


NT

On Dec 20, 2:00*pm, bookieb wrote:
Hi All,
snip
Any other advice or tips much appreciated on using this bit much
appreciated.

Regards,

bookieb.

Thanks to all who replied.

Will take it easy and keep the pressure light and speed moderate.

I'll try no hammer first - no great hurry anyway, and I'd sooner take
a bit longer than risk a bad jam.

If no/very limited progress, will try hammer.

Regards,

bookieb,

In article ,
harry writes:
If you buy the better expensive diamond drill,no hammer action. Some
need water cooling-ask.
TCT needs a hammer action, is not as expensive but usually there is a
breakout hole unless you drill from both sides.

Always try without hammer action first. If the brick is soft
and cuts easily, you get a better cut, and you may avoid
problems some bricks have when exposed to SDS hammer, where
the whole brick instantly disintegrates. Don't use hammer
on thermal blocks either, or to cut through the plaster layer.

It's very easy for a big drill like this to jam. Take extreme care. it
can break your wrist. Be sure your drill has a safety clutch, some
don't.

A friend had two nasty incidents doing this with a cheap SDS with
no saftey clutch.
First time the core jammed, the drill spun a part turn before the
drill body hit the adjacent wall, and then it wound up the arbor
like it was made of plasticine.
Next time, the drill body spun, whacked him on the chin, and
resulted in a visit to A&E and a few stiches.

Many small SDS drill won't handle it. Ask before you buy.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]