I have been experimenting with making keys for some of the flutes I’ve made from copper and PVC pipe plastic pieces (the copper one isn’t as functional). Currently I am using rubber bands to keep them closed but I’d like to try traditional flat springs. Perhaps even 3d print a key and integrate a flat spring mounting slot into it.
I am wondering if any flutemakers on here have found standard spring sizes and thicknesses from more common instruments (clarinet, sax) that can be easily modified for use on these closed-standing keys. Thanks for any input!
Ah, are they steel springs, Andy? I tried 0.5mm thick phosphor bronze springs and found them far too weak for flute keys!
I decided I prefer phosphor bronze keys as they are easier to work and won’t rust.
I ended up using 40mm long 0.7mm thick springs for the shorter keys. They come about 2.8mm wide at the end with the rivet hole in, tapering to about 1.8mm at the pointy end. They are still far too long but can be cut off and reshaped easily. I use a little 1” wide belt sander for reshaping.
I also found the ones I bought were too hard and could actually snap when trying to bend them. I partly anneal them, then hammer them lightly on the anvil to produce the degree of hardness I’m happy with.
For the long keys, I couldn’t find my ideal thickness, so just ended up using some 1mm thick sheet phosphor bronze. I cut 26mm wide strips of it on the bench shears.
Then I cut off strips of that 26mm long and about 3mm wide. Then use the belt sander to make them no wider than the key shaft at one end and more or less pointy at the other. I end up snipping a bit off when actually fitting the springs.
Getting leaf keys to work in a nice light and snappy way is quite an art (and some science!). If you don’t get it right the keys can be sluggish and heavy. Happy to talk about that further if it will help.