I don't see this documented anywhere, so I'll contribute this to our knowledge pool.
I have had a pair of Berthet pedals languishing in a dark corner for some years now because they had 1/2" spindles that were useless to me. Last weekend at the Cronometro swap I spotted a set of 9/16" x 20TPI Lyotard 45CAs for dirt cheap. The construction of both pedals is remarkably similar:
http://os2.dhs.org/
and it occurred to me that they might provide donor axles for my hitherto useless to me Berthets. Indeed, on removal the axles proved to be similar in all the important areas:
http://os2.dhs.org/
and the transplant was completely successful (the 1/2" Berthet axle is the bottom one in the picture; the donor 45CA axle is above it)!
Given that 45CAs are much more plentiful and cheap than Berthets these days (and a surprising number of NOS Berthets with 1/2" axles seem to appear on a regular basis) I thought I'd share this piece of information.
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-John Thompson (john@os2.dhs.org)
Appleton WI USA