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"toller"

15/01/2005 5:26 AM

Yet another wood movement question

If I was building this for myself, I would just go ahead and do it. But it
is for someone else, and it will be real embaressing if it falls apart.

I am building a butternut table/cabinet. I would like to use red oak as a
secondary wood; partly to save money (oak is half the price of butternut
here) and partly to add some strength in certain places. My handy dandy
movement chart says that butternut moves 0.10"/ft and oak moves 0.13"/ft
with a 7% moisture change. (I am only concerned with length; width will not
matter). Is this enough of a different to matter where 4' pieces are
screwed together? How about glued?

No other wood (except for cherry, which would be an obviously bad choice) is
as close to butternut as oak. But is it close enough?

Another wood movement question...
Everyone says plywood is stable. Does that mean it doesn't move at all (in
which case edge gluing should be a problem), or that it only moves like
other woods do with the grain?


This topic has 3 replies

JG

"Jeff Gorman"

in reply to "toller" on 15/01/2005 5:26 AM

15/01/2005 7:50 AM


"toller" <[email protected]> wrote in message

> Everyone says plywood is stable. Does that mean it doesn't move at all
> (in which case edge gluing should be a problem), or that it only moves
> like other woods do with the grain?

It certainly moves in thickness, usually to shrink over a period of time.

--
Jeff Gorman, West Yorkshire, UK
email : Username is amgron
ISP is clara.co.uk
www.amgron.clara.net

sD

[email protected] (Doug Miller)

in reply to "toller" on 15/01/2005 5:26 AM

15/01/2005 12:02 PM

In article <[email protected]>, "toller" <[email protected]> wrote:
>If I was building this for myself, I would just go ahead and do it. But it
>is for someone else, and it will be real embaressing if it falls apart.
>
>I am building a butternut table/cabinet. I would like to use red oak as a
>secondary wood; partly to save money (oak is half the price of butternut
>here) and partly to add some strength in certain places. My handy dandy
>movement chart says that butternut moves 0.10"/ft and oak moves 0.13"/ft
>with a 7% moisture change. (I am only concerned with length; width will not
>matter). Is this enough of a different to matter where 4' pieces are
>screwed together? How about glued?

Lengthwise movement is not an issue, regardless of the species. Changes in
moisture content produce negligible changes in length.

Why do you say width will not matter?
>
>No other wood (except for cherry, which would be an obviously bad choice) is
>as close to butternut as oak. But is it close enough?

If width really doesn't matter, and you're concerned only about movement along
the length of the boards, well.... length doesn't matter.
>
>Another wood movement question...
>Everyone says plywood is stable. Does that mean it doesn't move at all (in
>which case edge gluing should be a problem), or that it only moves like
>other woods do with the grain?

It isn't completely stable. It will change in thickness with changes in
moisture content, and it can warp as well.

--
Regards,
Doug Miller (alphageek-at-milmac-dot-com)

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Sk

"Swingman"

in reply to "toller" on 15/01/2005 5:26 AM

15/01/2005 8:38 AM

"toller" wrote in message ...
> If I was building this for myself, I would just go ahead and do it. But
it
> is for someone else, and it will be real embaressing if it falls apart.
>
> I am building a butternut table/cabinet. I would like to use red oak as a
> secondary wood; partly to save money (oak is half the price of butternut
> here) and partly to add some strength in certain places. My handy dandy
> movement chart says that butternut moves 0.10"/ft and oak moves 0.13"/ft
> with a 7% moisture change. (I am only concerned with length; width will
not
> matter). Is this enough of a different to matter where 4' pieces are
> screwed together? How about glued?

Width is actually what "matters" ... dimensional instability of wood in
"length" is generally negligible and can ususally be ignored in most
woodworking applications.

> No other wood (except for cherry, which would be an obviously bad choice)
is
> as close to butternut as oak. But is it close enough?

I would say that you are smart in choosing woods with similar stability
characteristics, as long as you understand how said wood reacts to factors
like relative humidity.

> Another wood movement question...
> Everyone says plywood is stable. Does that mean it doesn't move at all
(in
> which case edge gluing should be a problem), or that it only moves like
> other woods do with the grain?

Plywood does "move", so does MDF for that matter ... ANY wood, or wood
product is subject to dimensional instability with changes in relative
humidity and temperature.

However, the relative movement in sheet goods is generally so slight that it
can be effectively ignored for most woodworking projects, particularly with
the higher grade products.

--
www.e-woodshop.net
Last update: 11/06/04


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