Scotty Green asks about the addition of thin leather along the outer
edges of bellows stiffeners, on the inside face, which extend into the
glued joint.  He should certainly copy this design in his rebuilding.
In fact, this is the correct way of installing stiffeners in bellows,
if you are going to fit stiffeners.

Suction bellows may not need stiffeners but bellows that are supplying
pressure as well as suction must be fitted with stiffeners.  All edges
of the stiffeners must be so treated as this will prevent the stiffeners
un-peeling from the bellows cloth.  It is also acceptable to use cotton
tape along these edges such that the tape covers the hinge line on the
inside and is thus glued as a sandwich between the bellows board and
the bellows cloth.

Make sure you don't glue the stiffener too close to the bellows board
as this will prevent adequate movement as it folds in and out.  The
short edge of the stiffener should also be covered with thin leather
and often this leather covers the entire flexible gusset corner.  This
will also give additional life to the bellows as when the rubber cloth
inevitably fails at the corner, you will still have the security of the
inner leather membrane to make the seal.

As with all work of this type it is essential that only hot glue be
used.

I recently rebuilt the bellows of a Hupfeld orchestrion, which supplies
suction and pressure from a single set of four feeders, and this is the
design I found inside the original assembly.

Best wishes,
Nicholas Simons - GB