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Stringing a Rotary Valve

 

Take a length of strong nylon or Dacron cord and form a double knot at one end. Using a razor blade slice the string 45 degrees making a fine point on the end, This process is similar to threading a needle. Thread the cord through the hole.

Figure #1

Bring the free end partly around the stop-arm, counter-clockwise, having first loosened the string tightening screw on the stop arm.

Figure #2

Pass the cord clockwise under the screw head and adjust the lever so that it is approximately perpendicular to the rotor shaft when the stop arm is halfway through its stroke. Tighten the string screw.

Figure #3

Continue the cord counter-clockwise around the stop arm, under the first part, and thread it through the hole at the end of the lever.

Figure #4

With the lever being held in the open (up) position, wrap the cord clockwise around the string screw and tighten. The cord should be just loose enough to be deflected about 1/8 in. up the side of the stop arm. If the rotor binds, you might have to loosen this a slight amount. Cut off the excess cord, leaving about 1-½ inches of excess. Adjust the keys to level by loosening the string screw on the stop arm and adjust them each until they are level and about 1-¼ inch above the bell stem tubing. Re-snug the string screw, and test. Repeat if needed.

Figure #5

 

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