After postponing repair of a melodeon dating from perhaps the middle of
the 19th century, since I acquired it in about 1978, it has become of
interest.  I have two of these lovely little pump organs.  I returned
the more easily repaired one to serviceability about 30 years ago, but
the others repair very quickly ran aground because of the failure of
the connections of the removable legs.

The lyre-styled legs are located by pegs and affixed with ferrous
thumbscrews which thread into brass inserts in the case.  The threads
are quite worn and one of the inserts has broken into five or six
pieces.

I have tried various modern nuts on the thumbscrews and I've measured
the threads.  The diameter is about 5/16-inch, the thread pitch is
about 16 threads per inch, but the lead (advance per turn) is more
than a modern 5/16 x 18 NC thread.  My intent would be to replace the
brass inserts.  I suppose I could make new or modify the thumbscrews
using modern taps and dies.  Better ideas?

The other little difficulty with this melodeon is that the pump 
and reservoir are missing, as well as whatever sort of pedals it had.
I have seen a number of these organs and have collected lots of
photographs.  None I've seen adequately describe what the organ is
missing (but I'm sure I  can invent something).

Earlier organs of this type had suspended stirrups for the player's
feet; later, and more commonly, these things had pedals mounted on a
removable cross-member between folding legs.  The left pedal or stirrup
operated a swell and the right pumped negative pressure.

Douglas Heckrotte
Philadelphia, Pennsylvania
dheckrotte@gmail.com.geentroep [delete ".geentroep" to reply]

 [ The thread is possibly ASME 20-16, 0.32" diam.; ref.
 [ http://pages.cs.wisc.edu/~bolo/workshop/thread.html 
 [ See also https://en.wikipedia.org/wiki/Pump_organ#Melodeon 
 [ -- Robbie