Above my new french windows (a work in progress) there is an arch in
the brickwork. Because I'm bringing the frame 'forwards' by a brick's
thickness, I need to fill this space flush with the wall. The plan is
to put an appropriate arc of wbp ply into the gap on studs to be
finished etc.

The problem is how to get the curve right. It's essentially 'blind',
or I could offer a sheet of something to the wall and draw the shape
on it to make a template, so I need a cunning plan. Possible
solutions to date include:

1 Mould something around the opening that will set in the right shape
then use that as a template.
2 Paint something on the wall that will transfer onto a sheet of
something (hardboard/mdf etc) and press said sheet against the wall to
get a print of the shape.
3 Trial and error using thin mdf until I get it right.
4 Make a series of closely-spaced vertical measurements and draw it
as a 'join the dots' exercise.
5 Calculate the radius of the arc from its width and height, then
draw it with a pencil and piece of string (might be good if the house
hadn't moved a mm over the past 150 years).

Unfortunately none of these seems likely to be easy or successful, but
hopefully someone has solved the problem before and can suggest a
feasible solution before I get the angle grinder out and cut it to a
rectangle....

On Monday, March 19, 2012 11:16:41 PM UTC, GMM wrote:
Above my new french windows (a work in progress) there is an arch in
the brickwork. Because I'm bringing the frame 'forwards' by a brick's
thickness, I need to fill this space flush with the wall. The plan is
to put an appropriate arc of wbp ply into the gap on studs to be
finished etc.

The problem is how to get the curve right. It's essentially 'blind',
or I could offer a sheet of something to the wall and draw the shape
on it to make a template, so I need a cunning plan. Possible
solutions to date include:

1 Mould something around the opening that will set in the right shape
then use that as a template.
2 Paint something on the wall that will transfer onto a sheet of
something (hardboard/mdf etc) and press said sheet against the wall to
get a print of the shape.
3 Trial and error using thin mdf until I get it right.
4 Make a series of closely-spaced vertical measurements and draw it
as a 'join the dots' exercise.
5 Calculate the radius of the arc from its width and height, then
draw it with a pencil and piece of string (might be good if the house
hadn't moved a mm over the past 150 years).

Unfortunately none of these seems likely to be easy or successful, but
hopefully someone has solved the problem before and can suggest a
feasible solution before I get the angle grinder out and cut it to a
rectangle....

how would you seal it anyway?
just get it near enough and seal it as per plan - you can bet your last one it won't be exactly "arc shaped" but what does it matter in the final "seal the edges somehow" analysis?

Jim K

On Mon, 19 Mar 2012 16:16:41 -0700 (PDT), GMM wrote:

The problem is how to get the curve right. It's essentially 'blind',
or I could offer a sheet of something to the wall and draw the shape
on it to make a template,

Can't you offer up the sheet(*) and draw on the back of it? From you
description there does appear to be a recess ATM.

(*) Not a full sheet but a bit cut roughly to cover the area required
and let you have room to get in with a short pencil. Might need a
couple of other bods to hold it in place and ensure it doesn't move.

Perhaps easier to make a rough cut say 1" bigger but about the right
shape, offer that up and then just scribe it.

--
Cheers
Dave.

On 20/03/2012 00:09, Dave Liquorice wrote:
On Mon, 19 Mar 2012 16:16:41 -0700 (PDT), GMM wrote:

The problem is how to get the curve right. It's essentially 'blind',
or I could offer a sheet of something to the wall and draw the shape
on it to make a template,

Can't you offer up the sheet(*) and draw on the back of it? From you
description there does appear to be a recess ATM.

(*) Not a full sheet but a bit cut roughly to cover the area required
and let you have room to get in with a short pencil. Might need a
couple of other bods to hold it in place and ensure it doesn't move.

Perhaps easier to make a rough cut say 1" bigger but about the right
shape, offer that up and then just scribe it.


If the curve is uniform, could this work...
Piece of wood the width of the curve,
attach a long piece of stout card at one end,
then push the other end to flex it into the shape,
fix and copy the curvature of the card.

On Mar 20, 8:05*am, ss wrote:
On 20/03/2012 00:09, Dave Liquorice wrote:









On Mon, 19 Mar 2012 16:16:41 -0700 (PDT), GMM wrote:

The problem is how to get the curve right. *It's essentially 'blind',
or I could offer a sheet of something to the wall and draw the shape
on it to make a template,

Can't you offer up the sheet(*) and draw on the back of it? From you
description there does appear to be a recess ATM.

(*) Not a full sheet but a bit cut roughly to cover the area required
and let you have room to get in with a short pencil. Might need a
couple of other bods to hold it in place and ensure it doesn't move.

Perhaps easier to make a rough cut say 1" bigger but about the right
shape, offer that up and then just scribe it.

If the curve is uniform, could this work...
Piece of wood the width of the curve,
attach a long piece of stout card at one end,
then push the other end to flex it into the shape,
fix and copy the curvature of the card.

That sounds like a possibility - squidge it in and cut off the bent
bit to make a template?

On Mar 20, 12:09*am, "Dave Liquorice"
wrote:
On Mon, 19 Mar 2012 16:16:41 -0700 (PDT), GMM wrote:
The problem is how to get the curve right. *It's essentially 'blind',
or I could offer a sheet of something to the wall and draw the shape
on it to make a template,

Can't you offer up the sheet(*) and draw on the back of it? From you
description there does appear to be a recess ATM.

(*) Not a full sheet but a bit cut roughly to cover the area required
and let you have room to get in with a short pencil. Might need a
couple of other bods to hold it in place and ensure it doesn't move.

Perhaps easier to make a rough cut say 1" bigger but about the right
shape, offer that up and then just scribe it.

--
Cheers
Dave.

Unfortunately it's already 'blind' and the other side is the wall
inside (probably palter over timber) so I don't want disturb that and
make even more of a job of it than it is already!

GMM wrote:

Above my new french windows (a work in progress) there is an arch in
the brickwork. Because I'm bringing the frame 'forwards' by a brick's
thickness, I need to fill this space flush with the wall. The plan is
to put an appropriate arc of wbp ply into the gap on studs to be
finished etc.

The problem is how to get the curve right. It's essentially 'blind',
or I could offer a sheet of something to the wall and draw the shape
on it to make a template, so I need a cunning plan. Possible
solutions to date include:

1 Mould something around the opening that will set in the right shape
then use that as a template.
2 Paint something on the wall that will transfer onto a sheet of
something (hardboard/mdf etc) and press said sheet against the wall to
get a print of the shape.
3 Trial and error using thin mdf until I get it right.
4 Make a series of closely-spaced vertical measurements and draw it
as a 'join the dots' exercise.
5 Calculate the radius of the arc from its width and height, then
draw it with a pencil and piece of string (might be good if the house
hadn't moved a mm over the past 150 years).

Unfortunately none of these seems likely to be easy or successful, but
hopefully someone has solved the problem before and can suggest a
feasible solution before I get the angle grinder out and cut it to a
rectangle....

Do you need to cut it in? Sounds like you might persuade a square into
the back of the arch, behind it .. before you put the french windows in?

--
Paul - xxx
Mark cavendish Danny Hart
British Cycling World Champions 2011

On 19/03/2012 23:16, GMM wrote:
Above my new french windows (a work in progress) there is an arch in
the brickwork. Because I'm bringing the frame 'forwards' by a brick's
thickness, I need to fill this space flush with the wall. The plan is
to put an appropriate arc of wbp ply into the gap on studs to be
finished etc.

The problem is how to get the curve right. It's essentially 'blind',
or I could offer a sheet of something to the wall and draw the shape
on it to make a template, so I need a cunning plan. Possible
solutions to date include:

1 Mould something around the opening that will set in the right shape
then use that as a template.
2 Paint something on the wall that will transfer onto a sheet of
something (hardboard/mdf etc) and press said sheet against the wall to
get a print of the shape.
3 Trial and error using thin mdf until I get it right.

Much easier done with a sheet of stiff card and a pair of scissors.

4 Make a series of closely-spaced vertical measurements and draw it
as a 'join the dots' exercise.
5 Calculate the radius of the arc from its width and height, then
draw it with a pencil and piece of string (might be good if the house
hadn't moved a mm over the past 150 years).

.... and assuming it was built that accurately in the first place.

Colin Bignell

On Mar 20, 9:14*am, Nightjar
wrote:
On 19/03/2012 23:16, GMM wrote:









Above my new french windows (a work in progress) there is an arch in
the brickwork. *Because I'm bringing the frame 'forwards' by a brick's
thickness, I need to fill this space flush with the wall. *The plan is
to put an appropriate arc of wbp ply into the gap on studs to be
finished etc.

The problem is how to get the curve right. *It's essentially 'blind',
or I could offer a sheet of something to the wall and draw the shape
on it to make a template, so I need a cunning plan. *Possible
solutions to date include:

1 *Mould something around the opening that will set in the right shape
then use that as a template.
2 *Paint something on the wall that will transfer onto a sheet of
something (hardboard/mdf etc) and press said sheet against the wall to
get a print of the shape.
3 *Trial and error using thin mdf until I get it right.

Much easier done with a sheet of stiff card and a pair of scissors.

4 *Make a series of closely-spaced vertical measurements and draw it
as a 'join the dots' exercise.
5 *Calculate the radius of the arc from its width and height, then
draw it with a pencil and piece of string (might be good if the house
hadn't moved a mm over the past 150 years).

... and assuming it was built that accurately in the first place.

Colin Bignell

Indeed ! Perhaps it's moved and become straight? (Wishful thinking!)

Much easier done with a sheet of stiff card and a pair of scissors.

Or corrugated cardboard

GMM wrote:
Above my new french windows (a work in progress) there is an arch in
the brickwork. Because I'm bringing the frame 'forwards' by a brick's
thickness, I need to fill this space flush with the wall. The plan is
to put an appropriate arc of wbp ply into the gap on studs to be
finished etc.

The problem is how to get the curve right. It's essentially 'blind',
or I could offer a sheet of something to the wall and draw the shape
on it to make a template, so I need a cunning plan. Possible
solutions to date include:

1 Mould something around the opening that will set in the right shape
then use that as a template.
2 Paint something on the wall that will transfer onto a sheet of
something (hardboard/mdf etc) and press said sheet against the wall to
get a print of the shape.
3 Trial and error using thin mdf until I get it right.
4 Make a series of closely-spaced vertical measurements and draw it
as a 'join the dots' exercise.
5 Calculate the radius of the arc from its width and height, then
draw it with a pencil and piece of string (might be good if the house
hadn't moved a mm over the past 150 years).

Unfortunately none of these seems likely to be easy or successful, but
hopefully someone has solved the problem before and can suggest a
feasible solution before I get the angle grinder out and cut it to a
rectangle....

if the wall is plastered tack some mesh to the arch and use bonding
plaster to build a plaster wall..


--
To people who know nothing, anything is possible.
To people who know too much, it is a sad fact
that they know how little is really possible -
and how hard it is to achieve it.

On 20/03/2012 12:28, The Natural Philosopher wrote:
GMM wrote:
Above my new french windows (a work in progress) there is an arch in
the brickwork. Because I'm bringing the frame 'forwards' by a brick's
thickness, I need to fill this space flush with the wall. The plan is
to put an appropriate arc of wbp ply into the gap on studs to be
finished etc.

The problem is how to get the curve right. It's essentially 'blind',
or I could offer a sheet of something to the wall and draw the shape
on it to make a template, so I need a cunning plan. Possible
solutions to date include:

1 Mould something around the opening that will set in the right shape
then use that as a template.
2 Paint something on the wall that will transfer onto a sheet of
something (hardboard/mdf etc) and press said sheet against the wall to
get a print of the shape.
3 Trial and error using thin mdf until I get it right.
4 Make a series of closely-spaced vertical measurements and draw it
as a 'join the dots' exercise.
5 Calculate the radius of the arc from its width and height, then
draw it with a pencil and piece of string (might be good if the house
hadn't moved a mm over the past 150 years).

Unfortunately none of these seems likely to be easy or successful, but
hopefully someone has solved the problem before and can suggest a
feasible solution before I get the angle grinder out and cut it to a
rectangle....

if the wall is plastered tack some mesh to the arch and use bonding
plaster to build a plaster wall..


Any chance of a picture? it may help to see the problem.

On Mar 20, 12:28*pm, The Natural Philosopher
wrote:
GMM wrote:
Above my new french windows (a work in progress) there is an arch in
the brickwork. *Because I'm bringing the frame 'forwards' by a brick's
thickness, I need to fill this space flush with the wall. *The plan is
to put an appropriate arc of wbp ply into the gap on studs to be
finished etc.

The problem is how to get the curve right. *It's essentially 'blind',
or I could offer a sheet of something to the wall and draw the shape
on it to make a template, so I need a cunning plan. *Possible
solutions to date include:

1 *Mould something around the opening that will set in the right shape
then use that as a template.
2 *Paint something on the wall that will transfer onto a sheet of
something (hardboard/mdf etc) and press said sheet against the wall to
get a print of the shape.
3 *Trial and error using thin mdf until I get it right.
4 *Make a series of closely-spaced vertical measurements and draw it
as a 'join the dots' exercise.
5 *Calculate the radius of the arc from its width and height, then
draw it with a pencil and piece of string (might be good if the house
hadn't moved a mm over the past 150 years).

Unfortunately none of these seems likely to be easy or successful, but
hopefully someone has solved the problem before and can suggest a
feasible solution before I get the angle grinder out *and cut it to a
rectangle....

if the wall is plastered tack some mesh to the arch and use bonding
plaster to build a plaster wall..

--
To people who know nothing, anything is possible.
To people who know too much, it is a sad fact
that they know how little is really possible -
and how hard it is to achieve it.

Well, the wall around it is brick. It's inside the conservatory and,
ultimately (once I replace the conservatory) I shall be plaster
boarding the whole wall, so this is a bit of an interim measure.
Trouble is, the existing conservatory leaks a bit so I suspect any
plaster would get pretty tatty before I get to replacing the
structure, and there's little point in getting up there to seal
everything when it's going to come down anyway.

On 20/03/12 20:51, GMM wrote:
On Mar 20, 12:28 pm, The Natural
wrote:
GMM wrote:
Above my new french windows (a work in progress) there is an arch in
the brickwork. Because I'm bringing the frame 'forwards' by a brick's
thickness, I need to fill this space flush with the wall. The plan is
to put an appropriate arc of wbp ply into the gap on studs to be
finished etc.

The problem is how to get the curve right. It's essentially 'blind',
or I could offer a sheet of something to the wall and draw the shape
on it to make a template, so I need a cunning plan. Possible
solutions to date include:

1 Mould something around the opening that will set in the right shape
then use that as a template.
2 Paint something on the wall that will transfer onto a sheet of
something (hardboard/mdf etc) and press said sheet against the wall to
get a print of the shape.
3 Trial and error using thin mdf until I get it right.
4 Make a series of closely-spaced vertical measurements and draw it
as a 'join the dots' exercise.
5 Calculate the radius of the arc from its width and height, then
draw it with a pencil and piece of string (might be good if the house
hadn't moved a mm over the past 150 years).

Unfortunately none of these seems likely to be easy or successful, but
hopefully someone has solved the problem before and can suggest a
feasible solution before I get the angle grinder out and cut it to a
rectangle....

if the wall is plastered tack some mesh to the arch and use bonding
plaster to build a plaster wall..

--
To people who know nothing, anything is possible.
To people who know too much, it is a sad fact
that they know how little is really possible -
and how hard it is to achieve it.

Well, the wall around it is brick. It's inside the conservatory and,
ultimately (once I replace the conservatory) I shall be plaster
boarding the whole wall, so this is a bit of an interim measure.
Trouble is, the existing conservatory leaks a bit so I suspect any
plaster would get pretty tatty before I get to replacing the
structure, and there's little point in getting up there to seal
everything when it's going to come down anyway.
lots of cuts in cardboard from old boxes
to get closer approximations to the curve?

Or can foam?

But if theres a chance of water leaking in you dont want to seal it in
cos that would cause rot and mould
and make the future work much harder.

so if you use cardboard not ply then if theres any water getting in
it'll leak through and not stay in there and create damage?

[g]