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JohnC writes:
In recent Groopmail I've read about dowels being used to
reinforce, pin, whatever. I assiduously avoid this remedy.
Long breaks as shown need no pinning.
Good gluing technique will be more than adequate.
Bad breaks where there is substantial wood broken across
the grain need splices. One method I show effectively repairs
those breaks which have traditionally been doweled.
I've repaired hundreds of previously repaired dowel reinforcements.
They don't work. There is no continuity of grain at the ends of
the dowel. There the strength of previously good wood is now
reduced by the percentage of surface area of the cross-section
of the dowel to the surface area of the cross-section of the
structural member. See diagram.
On clean breaks 90 degrees to the grain, the only effective repair
that I have come up with is to turn a double-cone reinforcement
and bore the leg or whatever with a small diameter drill and then
ream the cone shape. I usually adjust the opening to the turning
as it is hard to chuck up the turning afterwards.
Glue is West System Epoxy with 405 Filler (great glue!)
This theoretically spreads the transition over a long distance just
as any scarf joint does. The pics are not of the double-ended
cone as one end was tenoned into the bottom of a case.
John Coffey
Locust Valley, NY
