I have a cheap circular saw from B&Q with a 20mm spindle and, I
think, 160mm blade. I want to get a thin blade for the saw to use to
cut access hatches in chipboard floors. Whenever I Google on the
subject clearly loads of references to products come up, but they
don't mention the width of cut. I did find a "fine" blade on the
Axminster site, but wasn't sure if that referred to the pitch or cut
width. Perhaps the 2 are related?

I was thinking of setting the saw to 45 degrees and just (!) deeper
than the board depth, then cutting a rectangular hatch.

What blade should I ask for and is this idea going to work anyway?

Thanks,
BraileTrail

"BraileTrail" wrote in message
...
I have a cheap circular saw from B&Q with a 20mm spindle and, I
think, 160mm blade. I want to get a thin blade for the saw to use to
cut access hatches in chipboard floors. Whenever I Google on the
subject clearly loads of references to products come up, but they
don't mention the width of cut. I did find a "fine" blade on the
Axminster site, but wasn't sure if that referred to the pitch or cut
width. Perhaps the 2 are related?

I was thinking of setting the saw to 45 degrees and just (!) deeper
than the board depth, then cutting a rectangular hatch.

What blade should I ask for and is this idea going to work anyway?

Thanks,
BraileTrail

Hi

Not sure that thin blades are an option

as the blade has to be thinner than the width of the teeth otherwise the
blade will bind I think that if you made the teeth narrower than say about 3
mm the blade wound become too thin to be stable

Even on a thin cut at 45 the material removed will cause the hatch to sit
lower than the surrounding floor

much better to make a vertical cut and batten around for support

Or better still use a router and those circular plastic inserts that fit
flush and take the routed out piece

Regards

"TMC" wrote in message
...

"BraileTrail" wrote in message
...
I have a cheap circular saw from B&Q with a 20mm spindle and, I
think, 160mm blade. I want to get a thin blade for the saw to use to
cut access hatches in chipboard floors. Whenever I Google on the
subject clearly loads of references to products come up, but they
don't mention the width of cut. I did find a "fine" blade on the
Axminster site, but wasn't sure if that referred to the pitch or cut
width. Perhaps the 2 are related?

I was thinking of setting the saw to 45 degrees and just (!) deeper
than the board depth, then cutting a rectangular hatch.

What blade should I ask for and is this idea going to work anyway?

Thanks,
BraileTrail

Hi

Not sure that thin blades are an option

as the blade has to be thinner than the width of the teeth otherwise the
blade will bind I think that if you made the teeth narrower than say about
3 mm the blade wound become too thin to be stable

Even on a thin cut at 45 the material removed will cause the hatch to sit
lower than the surrounding floor

much better to make a vertical cut and batten around for support

Or better still use a router and those circular plastic inserts that fit
flush and take the routed out piece

Regards

something like this

http://www.powertoolsuk.co.uk/webcat...e=RBT3&ID=1773

On 5 Oct, 15:09, "TMC" wrote:
Not sure that thin blades are an option

as the blade has to be thinner than the width of the teeth otherwise the
blade will bind I think that if you made the teeth narrower than say about 3
mm the blade wound become too thin to be stable

That sounds reasonable, but I thought I remembered thin blades being
available to cut vertically through T&G.

Even on a thin cut at 45 the material removed will cause the hatch to sit
lower than the surrounding floor

Yes, I had wondered about that. Oh well, on to plan B:

much better to make a vertical cut and batten around for support

It is much easier to get the depth right and there is no way to make a
cut with the blade 45 degrees the other way.

Or better still use a router and those circular plastic inserts that fit
flush and take the routed out piece

I do have one of these and they are very good in some circumstances,
but a) the hole is circular and b) it's quite small. I want to cut a
hatch about 2' x 3'.

Thanks,
BraileTrail

Or better still use a router and those circular plastic inserts that fit
flush and take the routed out piece

I do have one of these and they are very good in some circumstances,
but a) the hole is circular and b) it's quite small. I want to cut a
hatch about 2' x 3'.

How about pinning a batten to the floor as a guide, using the router
with the thinnest straight cutter to cut an oblong hole (accurate and
easy to set depth of cut) and then adding battens to support the
cutout?

mike wrote:
Or better still use a router and those circular plastic inserts that fit
flush and take the routed out piece
I do have one of these and they are very good in some circumstances,
but a) the hole is circular and b) it's quite small. I want to cut a
hatch about 2' x 3'.

How about pinning a batten to the floor as a guide, using the router
with the thinnest straight cutter to cut an oblong hole (accurate and
easy to set depth of cut) and then adding battens to support the
cutout?

Yes. You can't get close enough to the corners with a circ saw

BraileTrail wrote:
I have a cheap circular saw from B&Q with a 20mm spindle and, I
think, 160mm blade. I want to get a thin blade for the saw to use to
cut access hatches in chipboard floors. Whenever I Google on the
subject clearly loads of references to products come up, but they
don't mention the width of cut. I did find a "fine" blade on the
Axminster site, but wasn't sure if that referred to the pitch or cut
width. Perhaps the 2 are related?

I was thinking of setting the saw to 45 degrees and just (!) deeper
than the board depth, then cutting a rectangular hatch.

What blade should I ask for and is this idea going to work anyway?

Thanks,
BraileTrail

You need to look for fine "kerf" blades. (kerf = width of cut)
I buy dewalt saw blades designed for skil saws for this sort of work but
they are about 180 mm diameter with 16mm/5/8 bore.
I think you might have less choice with your size saw.
Covering the point raised in the thread about thickness & stability -
yes the saw plate must always be less than the kerf and will be less
rigid than a thick bodies blade but at 160mm diameter this is not likely
to be an issue.

Bob

Yes. You can't get close enough to the corners with a circ saw

I would have to accept some overrun yes, but it is covered by carpet.
Besides I can't see a straight router cutter less than 5mm with a 19mm
cut depth.

Thanks,
BraileTrail

On 5 Oct, 16:26, Bob Minchin wrote:
You need to look for fine "kerf" blades. (kerf = width of cut)
I buy dewalt saw blades designed for skil saws for this sort of work but
they are about 180 mm diameter with 16mm/5/8 bore.

Bingo! http://www.axminster.co.uk/product.a...16&src=froogle

Thanks,
BraileTrail

2' x 3' hatch? Most people put them under the patio :-)

Considering the price of the circular saw blade you cited, have you
consider a Bosch PMF180?

They will do a thin cut (might be 1.5mm rather than 1.3mm) and can do
a lot more re true "plunge-cutting". Basically a cheaper version of a
Fein Multimaster (some tools interchange).

BraileTrail wrote:
On 5 Oct, 16:26, Bob Minchin wrote:
You need to look for fine "kerf" blades. (kerf = width of cut)
I buy dewalt saw blades designed for skil saws for this sort of work
but they are about 180 mm diameter with 16mm/5/8 bore.

Bingo! http://www.axminster.co.uk/product.a...16&src=froogle

You will often find that blades for cordless saws are thinner to save
battery power,

I've found http://www.itslondon.co.uk/ very good for saw blades.


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

"TMC" wrote in message
...

"BraileTrail" wrote in message
...
I have a cheap circular saw from B&Q with a 20mm spindle and, I
think, 160mm blade. I want to get a thin blade for the saw to use to
cut access hatches in chipboard floors. Whenever I Google on the
subject clearly loads of references to products come up, but they
don't mention the width of cut. I did find a "fine" blade on the
Axminster site, but wasn't sure if that referred to the pitch or cut
width. Perhaps the 2 are related?

I was thinking of setting the saw to 45 degrees and just (!) deeper
than the board depth, then cutting a rectangular hatch.

What blade should I ask for and is this idea going to work anyway?

Thanks,
BraileTrail


I drylined all of my house with a product called Fermacell .... initially I
used a standard circular saw .. after one cut you could not see in the room
for 20mins .. the width of the blade turned that quantity into flour !

I bought a battery operated saw which by default use thin kerf blades (as it
takes less power to take a thin cut)

This proved excellent .. massive reduction in dust.

The saw I had was a Performance Power (B+Q) battery job .... anywhere that
sells DeWalt tools will have the saw blades.
http://www.diy.com/diy/jsp/bq/nav.js...LAID=350929832

On 5 Oct, 22:21, "Rick Hughes" wrote:

I drylined all of my house with a product called Fermacell .... initially I
used a standard circular saw .. after one cut you could not see in *the room
for 20mins

At the risk of diverting the thread a bit, what's it like in reality
(as opposed to the marketing puff)?

On 5 Oct, 16:55, "js.b1" wrote:
Considering the price of the circular saw blade you cited, have you
consider a Bosch PMF180?

I would be a bit worried about controlling the depth of cut and
getting a straight line by hand with that. However, thanks for the
pointer.

BraileTrail

Rick Hughes wrote:

I drylined all of my house with a product called Fermacell ....
initially I used a standard circular saw .. after one cut you could not
see in the room for 20mins .. the width of the blade turned that
quantity into flour !

I bought a battery operated saw which by default use thin kerf blades
(as it takes less power to take a thin cut)

This proved excellent .. massive reduction in dust.


Jigsaw with a scalloped 'bread knife' blade - cuts foam with no dust at
all.

Likewise I'd be inclined to use a jigsaw for the original floor cutting
job as the kerf is narrower than almost any circular saw. Shorten the
blade to the bare minimum to reduce the risk of hitting a pipe or cable
(although there's always some risk involved in blind plunge cutting).


--
Ian White

"The Medway Handyman" wrote in message
om...
BraileTrail wrote:
On 5 Oct, 16:26, Bob Minchin wrote:
You need to look for fine "kerf" blades. (kerf = width of cut)
I buy dewalt saw blades designed for skil saws for this sort of work
but they are about 180 mm diameter with 16mm/5/8 bore.

Bingo! http://www.axminster.co.uk/product.a...16&src=froogle

You will often find that blades for cordless saws are thinner to save
battery power,

I've found http://www.itslondon.co.uk/ very good for saw blades.


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

Happy to be corrected about the availablity of thin kerf blades

However would I not be correct in thinking that the 45deg cut idea is a bad
one as even with a total 3mm loss of material (1.5 from each end) the hatch
will sit lower than the surrounding floor when dropped back in?

Also fixing the hatch back in is more problematic with the angled cuts and
no battens

What would be wrong with the tried and trusted method of cutting vertically
adjacent to the joists and battening (having made the cross cuts first to
find the exact position of the joists) ?

Regards