Bay window has rot in the bottom of the 6 boards which form the boxes. Going to cut away and piece in new timber lower 6-12" or so each one. Could cut 90deg and put a couple of dowels in, or scarf to increase the connecting end grain area. Or something else?

On 26/09/2020 18:11, Peter wrote:
Bay window has rot in the bottom of the 6 boards which form the
boxes. Going to cut away and piece in new timber lower 6-12" or so
each one. Could cut 90deg and put a couple of dowels in, or scarf to
increase the connecting end grain area. Or something else?

I quite like doing a scarf joint since you can then use screws into the
face to bring the joint together. You can use a two part resin filler in
the joint as well to form the glue and exclude any voids in the process,
and fill the screw head holes (if countersunk a little).


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Saturday, 26 September 2020 at 19:10:59 UTC+1, John Rumm wrote:
On 26/09/2020 18:11, Peter wrote:
Bay window has rot in the bottom of the 6 boards which form the
boxes. Going to cut away and piece in new timber lower 6-12" or so
each one. Could cut 90deg and put a couple of dowels in, or scarf to
increase the connecting end grain area. Or something else?
I quite like doing a scarf joint since you can then use screws into the
face to bring the joint together. You can use a two part resin filler in
the joint as well to form the glue and exclude any voids in the process,
and fill the screw head holes (if countersunk a little).


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/
Thanks for the advice John. Scarf- at about 45deg? The boards are about 225 wide

On 26/09/2020 19:44, Peter wrote:
On Saturday, 26 September 2020 at 19:10:59 UTC+1, John Rumm wrote:
On 26/09/2020 18:11, Peter wrote:
Bay window has rot in the bottom of the 6 boards which form the
boxes. Going to cut away and piece in new timber lower 6-12" or so
each one. Could cut 90deg and put a couple of dowels in, or scarf to
increase the connecting end grain area. Or something else?
I quite like doing a scarf joint since you can then use screws into the
face to bring the joint together. You can use a two part resin filler in
the joint as well to form the glue and exclude any voids in the process,
and fill the screw head holes (if countersunk a little).

Thanks for the advice John. Scarf- at about 45deg? The boards are about 225 wide

That is usually adequate. A more acute from the end gives more contact
area, but is more difficult to cut by machine.

In some cases where there is space behind a board you can also
glue/screw in a section of bridging timber to give more mechanical
stability to the joint.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 26/09/2020 19:10, John Rumm wrote:
On 26/09/2020 18:11, Peter wrote:
Bay window has rot in the bottom of the 6 boards which form the
boxes. Going to cut away and piece in new timber lower 6-12" or so
each one. Could cut 90deg and put a couple of dowels in, or scarf to
increase the connecting end grain area. Or something else?

I quite like doing a scarf joint since you can then use screws into the
face to bring the joint together. You can use a two part resin filler in
the joint as well to form the glue and exclude any voids in the process,
and fill the screw head holes (if countersunk a little).

+1

But I prefer the space filling high strength high tack PU glues for
sealing the joint since the foam is somewhat more flexible to allow for
the wood dimensions varying with humidity. Two part resin filler looks
neater at first but invariably cracks after a year or two.

Two part is fine over the screw heads but I have always found that it
cracks sooner or later if used in a joint.

--
Regards,
Martin Brown

On 26 Sep 2020 at 19:44:01 BST, "Peter" wrote:

On Saturday, 26 September 2020 at 19:10:59 UTC+1, John Rumm wrote:
On 26/09/2020 18:11, Peter wrote:
Bay window has rot in the bottom of the 6 boards which form the
boxes. Going to cut away and piece in new timber lower 6-12" or so
each one. Could cut 90deg and put a couple of dowels in, or scarf to
increase the connecting end grain area. Or something else?
I quite like doing a scarf joint since you can then use screws into the
face to bring the joint together. You can use a two part resin filler in
the joint as well to form the glue and exclude any voids in the process,
and fill the screw head holes (if countersunk a little).


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/
Thanks for the advice John. Scarf- at about 45deg? The boards are about 225
wide

Is this joining at a piece of the original timber? If so, what's the best way
to cut away the joint face?

--
Cheers, Rob

On 27/09/2020 09:01, RJH wrote:
On 26 Sep 2020 at 19:44:01 BST, "Peter" wrote:

On Saturday, 26 September 2020 at 19:10:59 UTC+1, John Rumm wrote:
On 26/09/2020 18:11, Peter wrote:
Bay window has rot in the bottom of the 6 boards which form the
boxes. Going to cut away and piece in new timber lower 6-12" or so
each one. Could cut 90deg and put a couple of dowels in, or scarf to
increase the connecting end grain area. Or something else?
I quite like doing a scarf joint since you can then use screws into the
face to bring the joint together. You can use a two part resin filler in
the joint as well to form the glue and exclude any voids in the process,
and fill the screw head holes (if countersunk a little).


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/
Thanks for the advice John. Scarf- at about 45deg? The boards are about 225
wide

Is this joining at a piece of the original timber? If so, what's the best way
to cut away the joint face?

Multi-tool, carefully hand held. Maybe temporarily screw the new timber
onto the old with an overlap and make the 45 degree cut through both new
and old so the cuts match up. Naturally you must allow for the extra
x mm that will form the scarf joint.

On 27/09/2020 09:01, RJH wrote:
On 26 Sep 2020 at 19:44:01 BST, "Peter" wrote:

On Saturday, 26 September 2020 at 19:10:59 UTC+1, John Rumm wrote:
On 26/09/2020 18:11, Peter wrote:
Bay window has rot in the bottom of the 6 boards which form the
boxes. Going to cut away and piece in new timber lower 6-12" or so
each one. Could cut 90deg and put a couple of dowels in, or scarf to
increase the connecting end grain area. Or something else?
I quite like doing a scarf joint since you can then use screws into the
face to bring the joint together. You can use a two part resin filler in
the joint as well to form the glue and exclude any voids in the process,
and fill the screw head holes (if countersunk a little).

Thanks for the advice John. Scarf- at about 45deg? The boards are about 225
wide

Is this joining at a piece of the original timber? If so, what's the best way
to cut away the joint face?

On wider boards, then you can get a circular saw in there with the blade
set to bevel cut. Then complete with a multimaster of fine tooth handsaw
using the machine cut as an angle guide.

If space is more restrictive, then a reciprocating saw will get into
most places, but you will need more manual cleanup after. (those
Japanese saw rasps are fantastic for fettling things like that [1])

If doing it all freehand, then you could fix a 45 degree block to the
face to use as a guide, or just freehand and eyeball. (part of the
reason for using something gap filling as a glue!)

(there is a handy trick for cutting mitres by hand. You need a shiny
saw, and you watch the reflection of the wood you are cutting in the
saw. When the reflection shows you a nice right angle (which is quite
easy to judge by eye), you know you are cutting a good 45)


[1] https://www.axminstertools.com/japanese-saw-rasp-384015


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 27/09/2020 08:51, Martin Brown wrote:
On 26/09/2020 19:10, John Rumm wrote:
On 26/09/2020 18:11, Peter wrote:
Bay window has rot in the bottom of the 6 boards which form the
boxes. Going to cut away and piece in new timber lower 6-12" or so
each one. Could cut 90deg and put a couple of dowels in, or scarf to
increase the connecting end grain area. Or something else?

I quite like doing a scarf joint since you can then use screws into
the face to bring the joint together. You can use a two part resin
filler in the joint as well to form the glue and exclude any voids in
the process, and fill the screw head holes (if countersunk a little).

+1

But I prefer the space filling high strength high tack PU glues for
sealing the joint since the foam is somewhat more flexible to allow for
the wood dimensions varying with humidity. Two part resin filler looks
neater at first but invariably cracks after a year or two.

Two part is fine over the screw heads but I have always found that it
cracks sooner or later if used in a joint.

In reality any glue can fail if there is differential movement between
the parts. The foam of a PU glue does not have much strength though.
Something like gripfil may retain some flexibility for longer.
Ultimately trying to use a similar wood that will expand and contract at
a similar rate, and also painting everything really well to keep the
water out for as long as possible. (and ensuring things like drips,
seals, and flashings are in place and working)


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Andrew Wrote in message:
On 27/09/2020 09:01, RJH wrote:
On 26 Sep 2020 at 19:44:01 BST, "Peter" wrote:

On Saturday, 26 September 2020 at 19:10:59 UTC+1, John Rumm wrote:
On 26/09/2020 18:11, Peter wrote:
Bay window has rot in the bottom of the 6 boards which form the
boxes. Going to cut away and piece in new timber lower 6-12" or so
each one. Could cut 90deg and put a couple of dowels in, or scarf to
increase the connecting end grain area. Or something else?
I quite like doing a scarf joint since you can then use screws into the
face to bring the joint together. You can use a two part resin filler in
the joint as well to form the glue and exclude any voids in the process,
and fill the screw head holes (if countersunk a little).


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/
Thanks for the advice John. Scarf- at about 45deg? The boards are about 225
wide

Is this joining at a piece of the original timber? If so, what's the best way
to cut away the joint face?

Multi-tool, carefully hand held. Maybe temporarily screw the new timber
onto the old with an overlap and make the 45 degree cut through both new
and old so the cuts match up. Naturally you must allow for the extra
x mm that will form the scarf joint.


You ever done it?
--
Jimk


----Android NewsGroup Reader----
http://usenet.sinaapp.com/

On Sunday, 27 September 2020 at 17:08:38 UTC+1, John Rumm wrote:
On 27/09/2020 08:51, Martin Brown wrote:
On 26/09/2020 19:10, John Rumm wrote:
On 26/09/2020 18:11, Peter wrote:
Bay window has rot in the bottom of the 6 boards which form the
boxes. Going to cut away and piece in new timber lower 6-12" or so
each one. Could cut 90deg and put a couple of dowels in, or scarf to
increase the connecting end grain area. Or something else?

I quite like doing a scarf joint since you can then use screws into
the face to bring the joint together. You can use a two part resin
filler in the joint as well to form the glue and exclude any voids in
the process, and fill the screw head holes (if countersunk a little).

+1

But I prefer the space filling high strength high tack PU glues for
sealing the joint since the foam is somewhat more flexible to allow for
the wood dimensions varying with humidity. Two part resin filler looks
neater at first but invariably cracks after a year or two.

Two part is fine over the screw heads but I have always found that it
cracks sooner or later if used in a joint.
In reality any glue can fail if there is differential movement between
the parts. The foam of a PU glue does not have much strength though.
Something like gripfil may retain some flexibility for longer.
Ultimately trying to use a similar wood that will expand and contract at
a similar rate, and also painting everything really well to keep the
water out for as long as possible. (and ensuring things like drips,
seals, and flashings are in place and working)
--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/
Thanks everyone, lots of useful information there. If I screw a guide board at about 45deg to the existing, cut through with a handsaw/multitool then use the cut-away piece as template for new that should do it? Thinking Gripfill as glue, maybe drill shallow holes in each cut end to form sort of chemical dowels. I do have a circular saw and today bought my first multitool - for the bits of sill I need to cut out and will be needed for the boards forming a box corner - but generally feel more comfortable with hand tools. Please let me know if I've made any silly mistakes with the plan!
Cheers,
Peter

On 27 Sep 2020 at 17:04:47 BST, "John Rumm"
wrote:

On 27/09/2020 09:01, RJH wrote:
On 26 Sep 2020 at 19:44:01 BST, "Peter" wrote:

On Saturday, 26 September 2020 at 19:10:59 UTC+1, John Rumm wrote:
On 26/09/2020 18:11, Peter wrote:
Bay window has rot in the bottom of the 6 boards which form the
boxes. Going to cut away and piece in new timber lower 6-12" or so
each one. Could cut 90deg and put a couple of dowels in, or scarf to
increase the connecting end grain area. Or something else?
I quite like doing a scarf joint since you can then use screws into the
face to bring the joint together. You can use a two part resin filler in
the joint as well to form the glue and exclude any voids in the process,
and fill the screw head holes (if countersunk a little).

Thanks for the advice John. Scarf- at about 45deg? The boards are about 225
wide

Is this joining at a piece of the original timber? If so, what's the best
way
to cut away the joint face?

On wider boards, then you can get a circular saw in there with the blade
set to bevel cut. Then complete with a multimaster of fine tooth handsaw
using the machine cut as an angle guide.

If space is more restrictive, then a reciprocating saw will get into
most places, but you will need more manual cleanup after. (those
Japanese saw rasps are fantastic for fettling things like that [1])

If doing it all freehand, then you could fix a 45 degree block to the
face to use as a guide, or just freehand and eyeball. (part of the
reason for using something gap filling as a glue!)

(there is a handy trick for cutting mitres by hand. You need a shiny
saw, and you watch the reflection of the wood you are cutting in the
saw. When the reflection shows you a nice right angle (which is quite
easy to judge by eye), you know you are cutting a good 45)


[1] https://www.axminstertools.com/japanese-saw-rasp-384015

Thanks for that (and Paul), interesting - if unlikely in my case!
--
Cheers, Rob

On 27/09/2020 12:46, Jimk wrote:
Andrew Wrote in message:
On 27/09/2020 09:01, RJH wrote:
On 26 Sep 2020 at 19:44:01 BST, "Peter" wrote:

On Saturday, 26 September 2020 at 19:10:59 UTC+1, John Rumm wrote:
On 26/09/2020 18:11, Peter wrote:
Bay window has rot in the bottom of the 6 boards which form the
boxes. Going to cut away and piece in new timber lower 6-12" or so
each one. Could cut 90deg and put a couple of dowels in, or scarf to
increase the connecting end grain area. Or something else?
I quite like doing a scarf joint since you can then use screws into the
face to bring the joint together. You can use a two part resin filler in
the joint as well to form the glue and exclude any voids in the process,
and fill the screw head holes (if countersunk a little).


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/
Thanks for the advice John. Scarf- at about 45deg? The boards are about 225
wide

Is this joining at a piece of the original timber? If so, what's the best way
to cut away the joint face?

Multi-tool, carefully hand held. Maybe temporarily screw the new timber
onto the old with an overlap and make the 45 degree cut through both new
and old so the cuts match up. Naturally you must allow for the extra
x mm that will form the scarf joint.


You ever done it?

Yes. Successfully