Just took possession of one of these new-fangled Magnehelic flute leak detectors, becoming increasingly popular with top end Boehm flute maintenance technicians. I’d heard that they were very sensitive to the slightest leak, but I have to admit to being a little surprised just how sensitive. Plugged into a keyless flute body, it could still detect a slight leakage. When I wet my fingers first, the leakage went away. The thing was detecting the air leaking through the maze of my fingerprints!
I tried it on a Nicholson single-piece body which I knew was leaking at the G# and long F keys. Sure enough, vey bad leakage unless I squeezed both pads home. And an 1851 Patent Rudall Carte that had been repadded recently but not well enough to play the low notes reported as being an open tube!
A nice aspect of the machine is that it tests at positive pressure, not suction, so it doesn’t risk sucking the surface of the pad onto the hole, which can fool you if you only do a suction test. I can see it will be useful for tracking down “intermittent” problems such as keys with more than one stable rest position - they work fine most of the time but kill the low notes if you bump them.
Now at US $350, I’m not suggesting that the every home should have at least one. But if you have a flute with a pesky leak you’re having trouble pinning down, it could be worth finding out if any of your local flute repairers has one.
Isn’t that interesting! I now have yet another excuse . . .
“I’m so sorry this bites, but I believe I may be experiencing a higher than usual rate of dermal leakage.”
I wonder if this explains why I do better with clean, but creamed, hands, rather than freshly washed, dry-as-dust hands. My original thinking was that the hand cream gave a little traction to enhance hole coverage, but perhaps it aids in sealing the hole, too.
I think you could configure a manometer to do this. A manometer reads pressure difference between the two columns of air, whereas we want to read flow. But if you connected a supply of air at a suitable (low) pressure to one side of the manometer, the flute to the other and a needle valve or some other adjustable resistance between them the manometer would then register pressure dorp across, and therefore flow through the needle valve.
On the leaky fingers situation, the leakage seems to be below the level the leakage meter manufacturer reckons is significant. When I get a chance though, I’ll have a play with different hole profiles to see if a better profile could be found, and if such a profile would be practical in a flute.
I would be interested in how hole shape effects the seal.
Do rounded or sharp edges seal better? I assume that the smaller holes would have less of a tendency to leak than the larger holes. Some fifes have a couture on the pinkie, this depression makes it so there is more contact and extra room for the tenth hole. I wonder how the depression effects the seal.
Probably all minor and not worth worrying about except for that one time your finger dosen’t land quiet right
