Author: Chris P
Date: 2007-10-06 23:37
You've got it in a nutshell!
Only two springs in this part of the 8ve mechanism (on the right side of the picture) - the rocker carrier and lower (1st) 8ve key are both sprung closed - the upper (2nd) 8ve key isn't spring at all so when the rocker carrier is raised (by the thumb touch) the upper 8ve vent opens.
I originally designed it with the 2nd 8ve sprung open, but making a prototype showed it didn't exert enough pressure on the lower 8ve to keep it sufficiently closed, so I had the lower 8ve sprung closed.
Then when LH 3 is closed, the overlever (sprung lightly in an open position) from the main action presses onto the upper 8ve to close it (regulated by the adjusting screw), and this pressure is transmitted to the rocker which opens the lower 8ve only while the thumb is on the 8ve touch.
The rocker has nylon pins on either end (from Buffet clarinets) which fit into holes in the 8ve key arms so the rocker is permanently engaged in both 8ve keys. As the operational force is low, the nylon pins have very little risk of breaking, and also due to the low profile of this design it sits low in the case so there's minimal risk of crush damage from the case lid cushion. Stainless steel pins (made from adjusting screws with the heads rounded) can be fitted if desired.
Former oboe finisher
Howarth of London
1998 - 2010
Independent Woodwind Repairer
Single and Double Reed Specialist
Oboes, Clarinets and Saxes
NOT A MEMBER OF N.A.M.I.R.
The opinions I express are my own.
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