I’ve been having an e-correspondence with a young lady (secondary school pupil) from the US who is doing tooty things with plastic tubes for some kind of school project. Naturally I directed her to the obvious places - Doug Tipple’s and Guido Gonzato’s websites, the various flutomat type software, etc. I’ve also suggested she use this forum…
Anyway, she wrote something which made me mention the need for keys - must have been for outsize instruments where tone-holes go out of reach of hands and or finger-stoppable size - and then asked me what I meant by that. So… I’ve had various ideas lurking but had never actually experimented with them. Making keys to cover distant/large holes inevitably involves some kind of mechanism. My ideas were for not-too-long open-standing keys more-or-less just using the PVC of the tube and avoiding the need for hinges and springs - cut strips from it and use its inherent springiness, keep things as simple as possible. Rather than try to describe them in writing or even by drawing sketches, one afternoon last week I took to the shed and attacked some innocent PVC (mostly from my scraps box). They were crudely done in a hurry (should have been doing other stuff!) and not perfectly finished off or even properly adjusted, but they do actually work tolerably well. They would readily do so better made with refined design, experience, greater care all round and proper final adjustment. They’re not the best possible solution - proper pivotted or rod-axle keys like on flutes, or even Susato’s flap keys are better for sure, but require more complex building and probably greater skill to make.
I’m happy enough with them as prototype examples to share them. I think some folk here (DrPhill, Daniel B et al…) who play games with whistles below low C may be interested, and of course there are applications on higher whistles for folk with span problems or medical issues affecting their hands. I tried a few different ways of making open-standing keys. I haven’t tried to do closed-standing ones. Here are some pictures and short video clips of what I came up with.
The kind of scraps I was using - these have been heat-moulded to the outer surface of the tube
More scraps
Parts for assembly
Key “cup” with foam pad
The assembled key - mounting block to L, pad to R
Gluing the key into place on a scrap body tube
3 views of the assembled and mounted first experiment - an end-of-arm pad actuated by pressing on the arm near the fixed, mounted end (The taped over hole was already in the tube, so needed to be sealed to test the key)
2 views trying to show operation of the key with my hand positioned as if covering two neighbouring holes in playing position
Video of test-playing of the single end-of-arm type key - it works, but not brilliantly - the arm is a bit soft so does not readily press the pad down firmly with the relatively weak leverage applied by the finger near the mount without bending too much, and it is long and flexible enough to tend to go off true lateral alignment - but it does work and could be improved.
2 different versions of mid-arm pad keys, to be actuated by pressing on the free end of the arm once mounted
Direct arm-to-tube type mounted
Block-mounted type mounted
Operating the two mid-arm pad keys mounted onto a dummy tube with 3 tone-holes (not tuned or anything), with middle finger covering an open tone-hole in between the two keyed ones (which would not be reachable by fingers)
View of the mock-up 3-hole/2-key whistle segment
Mock-up fitted with whistle head to see if keys will actually work for “music” production!
Video of mock-up whistle tube segment with mid-arm keys. These work rather better, though stiffer outer parts of the arms could help, and I didn’t spend enough time/effort on getting the cups to close completely true onto the tube.
All parts are made from offcut scraps and strips of the same PVC conduit tube, sawn and filed to shape and bent as necessary to fit by softening with a hot air gun. They are just glued together/in place with superglue, and I doubt how well this will last, especially at the mounting points, with the stresses there. I think drilling a small hole right through the mount and inserting a small screw or pop-rivet (and making sure it was airtight by running in superglue) would be wise. FWIW, the design without a mounting block and the central pad seems to work best. One could of course use similar ideas to design closed-standing keys and ones with an axle/pivot, and very long ones would need guide lugs to keep them in line and protect them from knocks. Even these short ones are probably rather easy to damage. The “pads” are closed-cell neoprene foam (sheets easily available from craft sources), but I reckon scraps of old bicycle inner-tube rubber might work as well or better. For the second video and later photos I drilled 3 holes too far apart to finger (not tuned in any way - just holes…) in a scrap of tube and then mounted the two types of key (block and direct mounted), both with mid-positioned pads. The first attempt with an end-of-arm-positioned pad could do with a rather stiffer arm - was less easy to operate and not so reliable at closing properly, though as you see it did work tolerably. I’m not really sure how well even much more carefully made and adjusted ones would work for real music-making, but if others want to experiment with and refine the ideas, go for it!