How are pieces of wood joined together?
 

When I see large pieces of finished lumber, say a piece of 1" thick
oak thats a foot by 4 feet, it seems to be made of several pieces
joined together. Is this done because smaller pieces are cheaper or is
there some other reason? How are these joined together, is it by
bisuit joiner method or something more exotic? Will bisucit joined
lumber be as strong as lumber joined together in other ways?

The wood is glued together (called edge gluing). Biscuits, dowels,
splines etc. provide assistance in aligning the pieces and add some
strength, but its the glue that does the job. A biscuit is one of the
fastest and more reliable ways to add this alignment assistance.

Wider pieces of lumber are expensive and less available. Also, if you
use power tools for milling the lumber, width capacity translates to
more expense in the tool (initial cost plus ongoing blade replacement).
The primary culprit here is the power jointer. blade prices go up
exponentially with increases in width.

For furniture purposes, a glued board is as strong as a single piece of
wood. In fact the glued joint is usually considered stronger the wood.
Bob

glued up pieces are also less likely to split, or so says Norm.

"Bob" wrote in message
oups.com...
The wood is glued together (called edge gluing). Biscuits, dowels,
splines etc. provide assistance in aligning the pieces and add some
strength, but its the glue that does the job. A biscuit is one of the
fastest and more reliable ways to add this alignment assistance.

Wider pieces of lumber are expensive and less available. Also, if you
use power tools for milling the lumber, width capacity translates to
more expense in the tool (initial cost plus ongoing blade replacement).
The primary culprit here is the power jointer. blade prices go up
exponentially with increases in width.

For furniture purposes, a glued board is as strong as a single piece of
wood. In fact the glued joint is usually considered stronger the wood.
Bob

"ississauga" wrote in message
om...
When I see large pieces of finished lumber, say a piece of 1" thick
oak thats a foot by 4 feet, it seems to be made of several pieces
joined together. Is this done because smaller pieces are cheaper or is
there some other reason?

Narrow wood is easier to come by. There are few trees still to be harvested
that will yield very wide boards. Wide boards seem to warp easier but I
don't know what the optimum size is.

On Sat, 02 Oct 2004 02:39:47 GMT, "Edwin Pawlowski"
wrote:


"ississauga" wrote in message
. com...
When I see large pieces of finished lumber, say a piece of 1" thick
oak thats a foot by 4 feet, it seems to be made of several pieces
joined together. Is this done because smaller pieces are cheaper or is
there some other reason?

Narrow wood is easier to come by. There are few trees still to be harvested
that will yield very wide boards. Wide boards seem to warp easier but I
don't know what the optimum size is.

Some folks rip wider boards into smaller widths to minimize movement.
The grain is flipped with each alternating board so that if the wood
cups, it is less likely to cause the entire table to cup. The optimum
width I've heard for this is 4", but that may vary from person to
person.

On 1 Oct 2004 18:30:51 -0700, (ississauga)
wrote:

When I see large pieces of finished lumber, say a piece of 1" thick
oak thats a foot by 4 feet, it seems to be made of several pieces
joined together.

This is very common, although I'd be a little surprised to see oak
treated like that, in those sort of sizes. There are several reasons
to do it.

It's done for several reasons. Go to Ikea and look at their "solid
timber" products. These are nearly all thin strips of rubberwood
glued together, no more than an inch or two wide. Rubberwood is a
popular timber these days because it's sustainable (and not a bad
timber). When trees on a rubber plantation are worn out, they're now
felled for timber. They're only small though, so they must be joined
together to make a useful board.

In foot-wide oak, then you don't need to do this. Oaks are quite large
trees and sawn boards will already be this sort of size. You can buy
solid one-piece oak quite easily.

The problem with oak is that of timber movement. If you cut any
flat-sawn board, it tends to curve on drying - the rings in the tree
tend to go straighter.

One solution is to only use radial boards, which don't curve. In
medieval times this was done by splitting the tree rather than sawing
it (also easier work) to give very stable "riven" boards,
unfortunately wedge-shaped. Around 1900, the fashion was for
quarter-sawn oak timber, where consistent flat boards were sawn as a
good approximation of being radial. This is expensive sawing work,
because you need to keep turning the log round for each new cut, and
also because there's more timber lost as waste.

So if you're looking to build non-warping furniture from flat-sawn
oak, the usual solution is to saw the board narrower, then put it back
together. This would usually be done in the workshop though, not at
the timber yard. Boards are re-assembled either in the same order, or
more usually alternated up and down, so that any small warp that does
form becomes an even smaller "wiggle" instead. The width of the
boards used depends on the application, the thickness and the quality
of the timber. Boards flat-sawn from near the centre of a log are
comparatively stable (they're almost quarter sawn anyway), those near
the surface are less so.


For joining them, then it's done with glue. It's a long joint of the
long-grain face of the timber, so it's a strong join. Commercially
(Ikea) it's done by a huge machine. Commercially (small furniture
workshop) it's done by a manual clamping jig called a "panel press"
(search for "Plano", as the best-known maker). If you wish you can
also do it with biscuits. Biscuits add little to the strength, but
they make alignment easier if you only have bar clamps to hold it
together and not the alignment abilities of a press.


If you want to know more, any cabinetry book will tell you, or I
recommend Hoadley's "Understanding Wood" or the US Government Forest
Products handbook (paper copies available from Lee valley, or read it
as free PDFs on-line)
--
Smert' spamionam

Andy Dingley writes:


[...]

One solution is to only use radial boards, which don't curve. In
medieval times this was done by splitting the tree rather than sawing
it (also easier work) to give very stable "riven" boards,
unfortunately wedge-shaped. Around 1900, the fashion was for

Which gives rise to the question why you never see boards made from
two suck wedge-shaped ones glues together to form a rectangular slab?

--
Dr. Juergen Hannappel http://lisa2.physik.uni-bonn.de/~hannappe
Phone: +49 228 73 2447 FAX ... 7869
Physikalisches Institut der Uni Bonn Nussallee 12, D-53115 Bonn, Germany
CERN: Phone: +412276 76461 Fax: ..77930 Bat. 892-R-A13 CH-1211 Geneve 23

writes:

[...]


if you have the technology to get riven boards flat enough to glue
them together you almost certainly have the technology to saw the
board you want out of the log.

Ok, riven boards are to "wavy". But if you saw the trunk into
wedge-shaped boards you would have only true "quartersawn" surfaces,
and could then glue them up to rectangular-sectioned boards, with
minimal losses.

--
Dr. Juergen Hannappel http://lisa2.physik.uni-bonn.de/~hannappe
Phone: +49 228 73 2447 FAX ... 7869
Physikalisches Institut der Uni Bonn Nussallee 12, D-53115 Bonn, Germany
CERN: Phone: +412276 76461 Fax: ..77930 Bat. 892-R-A13 CH-1211 Geneve 23

On Sat, 02 Oct 2004 16:44:55 +0200, Juergen Hannappel
wrote:

Andy Dingley writes:


[...]

One solution is to only use radial boards, which don't curve. In
medieval times this was done by splitting the tree rather than sawing
it (also easier work) to give very stable "riven" boards,
unfortunately wedge-shaped. Around 1900, the fashion was for

Which gives rise to the question why you never see boards made from
two suck wedge-shaped ones glues together to form a rectangular slab?


if you have the technology to get riven boards flat enough to glue
them together you almost certainly have the technology to saw the
board you want out of the log.

On Sat, 02 Oct 2004 16:44:55 +0200, Juergen Hannappel
wrote:

Which gives rise to the question why you never see boards made from
two suck wedge-shaped ones glues together to form a rectangular slab?

That is a _very_ good idea....

On Sat, 02 Oct 2004 18:37:29 +0100, Andy Dingley
wrote:

On Sat, 02 Oct 2004 16:44:55 +0200, Juergen Hannappel
wrote:

Which gives rise to the question why you never see boards made from
two suck wedge-shaped ones glues together to form a rectangular slab?

That is a _very_ good idea....


why?

On Sat, 02 Oct 2004 11:30:31 -0700, wrote:

why?

Because I have a froe, a lot of logs too narrow to quartersaw, and an
idea...

On Sat, 02 Oct 2004 11:30:31 -0700, scribbled:

On Sat, 02 Oct 2004 18:37:29 +0100, Andy Dingley
wrote:

On Sat, 02 Oct 2004 16:44:55 +0200, Juergen Hannappel
wrote:

Which gives rise to the question why you never see boards made from
two suck wedge-shaped ones glues together to form a rectangular slab?

That is a _very_ good idea....


why?

More QS wood from the same tree (less waste), wider QS planks from the
same tree. The only disadvantage I can think of now is that the edges
of the plank would have a glue line.

Are we missing something? Why hasn't it been done? Is it a question of
cost, i.e the effort is not worth the additional wood? Or did Juergen
have a true inspirational moment?

Luigi
Replace "nonet" with "yukonomics" for real email address
www.yukonomics.ca/wooddorking/antifaq.html
www.yukonomics.ca/wooddorking/humour.html

Luigi Zanasi said:

On Sat, 02 Oct 2004 11:30:31 -0700, scribbled:

On Sat, 02 Oct 2004 18:37:29 +0100, Andy Dingley
wrote:

On Sat, 02 Oct 2004 16:44:55 +0200, Juergen Hannappel
wrote:

Which gives rise to the question why you never see boards made from
two suck wedge-shaped ones glues together to form a rectangular slab?

That is a _very_ good idea....


why?

More QS wood from the same tree (less waste), wider QS planks from the
same tree. The only disadvantage I can think of now is that the edges
of the plank would have a glue line.

Are we missing something? Why hasn't it been done? Is it a question of
cost, i.e the effort is not worth the additional wood? Or did Juergen
have a true inspirational moment?

While cutting up some pin oak the other yesterday, I wondered the same
thing. I had all these wedge shaped pieces left over - what could I
do with them, rather than the fireplace?

FWIW,

Greg G.

On 1 Oct 2004 18:30:51 -0700, (ississauga)
wrote:

When I see large pieces of finished lumber, say a piece of 1" thick
oak thats a foot by 4 feet, it seems to be made of several pieces
joined together. Is this done because smaller pieces are cheaper or is
there some other reason? How are these joined together, is it by
bisuit joiner method or something more exotic? Will bisucit joined
lumber be as strong as lumber joined together in other ways?

It is more difficult to obtain wider boards than 100 years ago
narrower boards are glued together. There are various ways to join
wood but woodworking glue is usually strong enough. Biscuits do not
add much strength but they are good for alignment.

Luigi Zanasi writes:


[...]

Are we missing something? Why hasn't it been done? Is it a question of
cost, i.e the effort is not worth the additional wood? Or did Juergen
have a true inspirational moment?

I definitely did not have a true inspirational moment, because the
idea is not mine but rather comes from an aegyptologist whom i happen
to know , so maybe it's a *very* old idea indeed...

--
Dr. Juergen Hannappel http://lisa2.physik.uni-bonn.de/~hannappe
Phone: +49 228 73 2447 FAX ... 7869
Physikalisches Institut der Uni Bonn Nussallee 12, D-53115 Bonn, Germany
CERN: Phone: +412276 76461 Fax: ..77930 Bat. 892-R-A13 CH-1211 Geneve 23