Wednesday, July 18, 2012

Sneaky Leaks


Windworks Studio of Philadelphia

Bev and Linz (“The Girls in Philly”)

Any leak, no matter how small, affects the sound and speed of flutes - not to mention the extra work required to have the flute perform.  What’s important to remember is that leaks are not limited to pads, their installation or to tenon fit.  Insidious leaks can hide in the headjoint!  These types of leaks are tricky to locate and are only solved by accurate diagnosis.

Obviously, head cork leaks are more common than leaks from other parts of the headjoint. So, here are some tips, as well as a foolproof step-by-step approach to find the problem.

Always and often:

Step 1) Pressure test the headjoint on the Magnehelic with the head cork in place.  You want a perfect zero.  If it zeros out, the headjoint is “OK.”

Fig 1: Correct Pressure Test reading at “Zero.”


If it fails to zero out, before you replace the cork, do the next test in Step 2;

Fig. 2: Initial Pressure Test Failure with head cork in place


Step 2) Remove the head cork assembly.  Put in a rubber stopper.  Pressure test the lip plate assembly and tube joints.  Does it zero out?  If not, try the next test;

Fig 3: Pressure test with rubber stopper  (head cork assembly removed)


Step 3) Submerge the headjoint in water while pressure testing.  Bubbles will lead you to the leak location.  What to do now?

Fig 4: Movie of Solder Failure Lip Plate assembly water test under pressure

video

Step 4) Unless, you are a headjoint maker, it’s best to send the head joint back to the maker for the leak to be addressed.  It may be helpful to review an earlier post written by Steven Wasser on different types of solder techniques, titled “Why Solder Matters” a June 6, 2012 entry on the Flute Builder Blog. 

Enjoy your work and remember when you want to be a “perfect zero”!

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