Stephen M wrote:
> The reason the equal parts appraoch does not optimise joint
> because the bending strength of wood is not linear with thickness.
> that is a function of the square of thickness. If
> Hopefully someone with a mechanical engineering background can back
> or shoot me down :-) on this one.
Close, but no cigar, the equal parts approach does produce the best
Think you may be thinking of the moment of inertia calculation used
when computing the stress of a beam as an example.
Picture a rectangle with a base dimension of "B" and a height of "H".
The moment of inertia (A mathematical statement about a shape) for the
rectangular section is as follows:
"I", The Moment Of Inertia, is defined as I = (B*H^3)/12
Section Modulus, "Z", is defined as I/(H/2)
Stress, "S", is defined as M/Z.
Based on the above, the strength of of a section varies as the cube of
the height of the section.
To make this as simple as possible, tall skinny pieces are stronger
than short fat ones when subjected to a bending load.
The fact that the mortise has two (2) walls that are each 3/16, thus a
3/8 total which equals the 3/8 tenon will produce a "balanced" joint.
HTH, didn't want to bore you with the dull stuff, but you asked<G>.
Thanks to all who gave advise. A mortising I will go.