I’ve seen plans for cases to be constructed using a less expensive wood, such as tulip/yellow poplar, in areas that won’t be seen like the case bottom. The two cases I refer to had cherry and walnut repectively as the primary woods paired with a yellow poplar bottom and subtop edged with a glued on strip of the primary wood. Are different expansion rates between the species ever a problem if joined with half blind dovetails?
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Replies
"Are different expansion
"Are different expansion rates between the species ever a problem if joined with half blind dovetails?"
In my experience, the answer is seldom. However, I'd be a little more concerned if the chosen woods exhibit markedly different shrinkage factors in what I call the "Shrinkage Zone", ie, 30%-0% MC. For instance, if you used radially sawn mahogany (a very small mover) and tangentially sawn European beech (a large mover) as the pairing it's possible there could be differential movement problems that might show up as splits in either species.
The likelihood of splits or failures showing up in service would increase the greater the the change in the moisture content of the wood over the seasons. And those numbers are controlled primarily by the range of relative humidity in the final location of the item. In most houses RH values usually range between about 20 and 35 percentage points, eg, winter average about 30% and summer about 60% RH equating to wood MC numbers of roughly 6% and 11.5%. Therefore, typically most furniture needs to be able to cope with changes in size caused by about 5%- 6% change in MC.
I always like to allow for more than this, closer to 8% or 10% change in MC because you just never know where the furniture you make may end up, eg, long term storage in a facility with no climate control. Slainte.
Richard.. Good points..
And I have seen some ancient and very old furniture with dovetail drawers that looked like the 'joints' were filled with mud and left to dry!
They seem to survive 'time'....
"with dovetail drawers that
"with dovetail drawers that looked like the 'joints' were filled with mud and left to dry!"
WG, it's remarkable sometimes how successfully not so well executed joinery manages to hang together over decades, or even centuries. I've pulled apart very old chairs that, upon subsequent examination, had hung in there reasonably well for all that time despite some pretty sloppy M&Ts. Slainte.
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