A flute of my acquaintance has a short F key with a less-that-perfect feel. Whereas some flutes I’ve played have a key which depresses smoothly then snaps back into place, this one is tough to get moving, but seems to lose its oomph on the way back down to close up again. Upon further inspection, the spring on the errant key is bent in a simple curve, like a parenthesis; the ones I like the feel of have a spring that’s bent more into a J-curve, with the straighter part going to the rivet.
Any of you flutemakers have an opinion as to whether this might be the critical difference?
Normally on a Short F you do see more like the J shape you describe, because of the need for the spring to avoid touching anywhere along its length except its tip. Because the key shaft is curved (while all the other keys are straight), that usually requires the spring to be more curved especially near the tip end.
First thing to try is just a spot of grease on the tip of the spring - it could be friction with the striker plate that is causing the poor spring response. Check that the striker plate is clean and is not showing excess wear - if the spring has dug itself a hole that can cause problems.
As Jon has mentioned, check that the spring hasn’t cracked. It can be hard to see a crack around the rivet, expecially if it’s under buffer cork.
It could also be that the spring is touching somewhere other than the tip, or that the spring is too short. Both will result in heavy action and sluggish response. Any of these last problems will require the spring to be replaced.
Thanks for the responses, guys. After a thorough check, I can report that the spring is not cracked, nor is it touching the sides of the keyway. It is, however, made of phosphor bronze, rather than brass as in the two I like the feel of. At one point, it had indeed dug a hole, but I installed a striker plate of spring steel, so that problem is more or less solved. Still don’t like the feel. Might a brass spring help? This also happens to be the key I considered double-springing in another thread. Cheers,
You may just need to smooth off the contact tip of the spring, Rob - either by bending just the last mm up in a slight recurve with pliers (may require subsequent adjustment of spring weight by altering the curve elsewhere, and some commercial springs have the recurve ready made) or by filing it to a smooth roundness with a very fine engineering needle file and buffing with fine abrasive paper to ensure a smooth contact surface. Try the latter and a dab of grease before any more serious surgery. The actual material of the spring should not affect its performance, though it may be that a ready-made phosphor bronze spring is too light because too thin for this application, regardless of how adjusted. If you make a brass or cupro-nickel one yourself you can at least have more control over its precise final dimensions/action.
When I did a new spring for the short F of the Keith Prowse I overhauled recently, it was initially sluggish just as you describe. That proved partly due to it working across until it rubbed the side of the key slot (because of the poor alignment of the key/block-channel/tonehole), which I solved, but it was still sluggish. I felt it was too heavy, but could not reduce the spring’s curve without the spring tip loosing contact with the strike plate and ceasing to work at all… the solution proved to be to retain the same curvature and to file the spring thinner and lighter which both reduced the finger pressure required to operate it and eased the action. But in the past I’ve noticed the same effect from too light a spring.
This isn’t really relevant to your case, Rob, but is another possible cause for similar symptoms (while we’re on the subject). A while back the short F spring on my R&R went sluggish and the cause proved to be that the tip of the main brass spring had worn away except at one side where it had formed a little tongue where it was lapping over the edge of the steel counter-spring - to the point where it was starting to jam between the counter-spring and the slot wall! That could happen with a poorly fitted strike plate too, though not very quickly - and you’ve only just fitted yours.
Ah, but carefully! It is well centered, and large enough to preclude that particular problem. Meanwhile, the spring tip is polished smooth, and I’ve greased the striker pate already; I think we’re left with the feel of the spring itself. I might go for a brass spring, in which case I’d like to know what sort of brass is correct. Cheers,
Dunno about “correct” - I believe you can get sheet brass (from engineering supplies, or try your local school’s CDT staff if you know them) from which to clip key-blanks, or you could hammer some brass rod (as easily available from DIY or modelling stores) flat with suitable annealing along the way. You could possibly even cannibalise brass parts out of old electrical goods… I’m not sure how much variation there is in brass alloys or how discernible a difference it would make in any spring you might make. However, I and others have had good success in using the tines or shafts of old EPNS forks as source material for replacement tempered leaf springs (as well as using old nickel-silver cutlery for replacement parts for broken or missing German Silver keys). It’s not true brass, but it will do the job just as well.
See pictures in sequence after this one - hope that helps a bit.