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MMD > Archives > March 2006 > 2006.03.07 > 10Prev  Next

Replicating Duo-Art Accordion Pneumatics
By Paddy Handscombe

Duo-Art accordion sections 1, 2, 4 and 8 do move of course 1/16, 1/8,
1/4 and 1/2" respectively, but it is quite incorrect -- and impossible
-- simply to make the cloth spans these actual dimensions: allowance
must of course be made for the height of the adjusters.

The following exact dimensions for a normal four-section Duo-Art
accordion were taken from an original Aeolian UK drawing at the Musical
Museum in London:

  Top moving board/cloth thickness        1/4"
  Dynamic 1 cloth span                    1/4"
  2nd moving board/cloth thickness        3/8"
  Dynamic 2 cloth span                    5/16"
  3rd moving board/cloth thickness        3/8"
  Dynamic 4 cloth span                    7/16"
  4th moving board/cloth thickness        3/8"
  Dynamic 8 cloth span                    5/8"
  Fixed board/cloth thickness             1/2"
  Total cloth width/accordion height    3-1/2"

Striker pneumatic rubbercloth was mostly used to cover UK-made
accordions and in my experience gives better service and accuracy
than leather.  Mark out the cotton side of the cloth with these
dimensions and the board corner positions; stick the boards on neatly
with PVA adhesive one side at a time and allow them a few minutes to
relax and set, placing a book on the top edges of the boards to keep
them upright and regular.  This way accordions can be made accurately
without any twist or skew and without the need for spacers or a jig.
Once the adhesive is set, trim the cloth edges and cut the holes for
the nipples with a small scalpel blade.  Push the nipples in with
a tiny smear of PVA to make a sealing donut.

Then refit the adjusters and set the correct travel.  Make a jig with
a spring to extend the accordion, and a rule to measure the actual
travel at the top stirrup when sucking the sections firmly closed.
This is the only way to mimic the real behaviour of the accordion.
All three adjustments on each board should be even and spot on.  Later,
if water-gauge readings reveal a minor cyclical aberration of the
dynamic curve, the guilty accordion section may be tweaked slightly
to get the build-up perfect.  Needless to say, both Theme and
Accompaniment accordions should be identical.

The webbing straps which were sometimes fitted between the top and
bottom boards to limit the overall stretch of leather-covered
accordions were simply an ignorant mistake and are incompatible with
correct operation, as the intermediate boards invariably loll around
and cannot apply their full motion: omit them!

Patrick Handscombe
Wivenhoe, Essex, UK

(Message sent Tue 7 Mar 2006, 21:05:11 GMT, from time zone GMT.)

Key Words in Subject:  Accordion, Duo-Art, Pneumatics, Replicating

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