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'
"Mike Marlow" wrote in message
...

"J" wrote in message
...

And is much wider. The cross section of the typical biscuit is much
larger
than the cross section of the dowel.
A #20 biscuit has a cross sectional area of 0.35 sq in. You would need a
dowel 2/3 inches in diameter to match that cross section.
Not easy to use that size of dowel in 4/4 stock. :-) This is why the
loose
tenon was invented.


What about the cross section of two dowels in the same space a biscuit
would
occupy?

Do the math.
Cross section of dowel = PI x r^2
Cross section of biscuit = length x thickness (#20 is 2.375 x 0.147)
So it would take three 3/8" diameter dowels to match the shear strength of
a #20 biscuit or two 1/2" dowels.
Assuming the same strength of materials.

-j