The Flute Maker
Traditional keywork has changed little since Boehm's day, except in a very restricted stylistic way (e.g. French arms etc.), but it has become more massive, possibly to help it last longer. For too long its role in determining the acoustic character of the flute has, in mv view, been neglected.
I have used stainless steel for keywork right from the beginning, for the fight against weight. It has about 3/4 the density of silver, yet roughlv three times the stiffness (i.e. resistance to getting bent). This means you need less of it for comparable strength, thereby getting the weight of keywork down to about half that of silver. Of course it is much harder too and does not tarnish. There is no doubt that this weight difference has a huge effect on the way the flute plays, yet seems to be a factor largely ignored by most makers. If the tube is considered to be the acoustic heart of the instrument. sensitively and accurately made, I should have thought it vital not to encumber it too much with dense and complex kevwork. If a comparison is drawn between the major woodwind instruments in terms of the ratio: total key weight (including strapping) to tube weight, the tvpical modern flute is at the high end of the scale with the bassoon at the bottom. I suggest that the flute is therefore more sensitive to changes in kev weight than the others. Sticking on an extra trill key here or a gizmo there may well result in a subtle change in response which could go unnoticed on the heavier wooden instruments. I am talking here about overall key weight. The weight, or more strictly inertia, of an individual key is also important for playability, or feel, of the instrument and should be distinguished from spring tension that can of course be adjusted. The speed at which a key can open depends on both factors.
Working in stainless steel requires different techniques to those used for precious metals. As it cannot easily be forged or cast, cutting then filing is really the only way. Many of the parts are roughed out of standard plate using a computer controlled laser or water jet cutter, then laboriously finished by hand with a variety of needle files and miniature sanding drums. The actual cups are turned from solid bar rather than pressed from sheet. This means that the pad seatings can be made absolutely flat, instead of the usual dish shape, making subsequent padding much easier and longer lasting. One of our original weight-saving ideas was to cut away the top surface of all the keys and to inlay a hard black plastic; this results in an unusual appearance (almost the reverse of a blackwood flute with silver keywork) and a very comfortable slightly warm touch. This has now become my visual trademark.