Wednesday, August 22, 2012

The Boston Wall

Close-up on headjoint wal
Our fourth installment in Steven Wasser's series on headjoints addresses the wall -- or riser, or chimney.  Many names for an integral part of the headjoint.  What are some of the characteristics of this piece?  How is it attached to the headjoint?  Find out below...

The wall of the headjoint is also referred to as the riser or chimney, and is primarily responsible for the shape of the embouchure hole.  The wall is multi-dimensional and extremely difficult to measure.  This difficulty keeps headjoint makers in business.  If the embouchure hole were easy to measure, it could be made entirely by machine. 

To the extent that a wall can be measured there are several critical dimensions:

  • Height which may be different at the front and the back of the wall
  • Side to side diameter
  • Front to back diameter
  • Diagonal
  • Interior angles which again may be different front and back and which are also compounded from multiple angles

The way a wall is attached to the tube and lip plate also affects acoustics as well as durability.  Most headjoint makers silver braze the lip plate to the wall then soft solder the lip/wall assembly to the tube.  A silver brazed joint acts as if the joined pieces were one metal and has a strength of 40,000 psi; a soft soldered joint typically behaves more like a metal glue and normally has a tensile strength of 4,500 psi.  Powell has developed technology that allows the lip/wall assembly to be silver brazed to the tube.
Lip plates and walls

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