Mitch explains:

<You are correct in recognizing that a wane edge (outermost growth ring) of
the
timber being dendrochronoligized must be present.  The dendro work done here
in
North Carolina - largely in the eastern part of the state- was performed by
Jack
Heikkenen of Blacksburg VA.  He developed a statistical methodology - which
he
patented - for comparing the width of one growth ring with the width of the
subsequent ring. As I recall he required a minimum of eight samples per
structure .  Joists, rafters and other timbers with a wane edge were needed
to
be statistically accurate.  He would then identify a series of key years and
compare these to a known dated sample to determine when the tree was
felled.>

This actually is not problematic in most old frames I have surveyed or
worked on. Trees are heavy and the closer you can get to the timber just
fitting in the log the better for handling during the hewing process. Plus
hewing is hard work, so the less you gotta take off the better. It's common
to find wane on an edge of a timber and not uncommon to find it on two edges
or more. Another factor that will give you a waney edge or two is how much
sweep is in the log. It might have four square corners on one or both ends,
but will show wane somewhere near the middle. Sometimes LOTS of wane.

Running it through the time machine helps a little but not always.

Rudy