Dear Colleagues,
I don't know if this will solve David's problem, the one that started this whole thread. Since David hasn't seen the piano yet, we don't know any of the particulars; with any luck, David, you might be able to make enough improvements to get the piano to repeat adequately. All the best to you tomorrow! I hope it's something easily reproducible and fixable, like sluggish jacks or cheating jacks...
If I understand Scott Thile's description of his problem, it sounds like the hammer is sinking below the normal hammer line. I encountered this problem about 25 or 30 years ago on new Steinways, model B mostly. It was always in the low tenor, from about F3 on down, perhaps once in a while at the top of the bass section. To replicate the problem, you play the note to put it into check, and then release it very slowly. Hammer shank goes all the way down to the rest felt, below the level of the other hammers. You can't play the note again without first sort of bumping the key around to get the jack under the knuckle. Does this sound familiar, Scott?
If all the friction points are within spec, esp. jacks not pinned too tightly and adequate friction (5 to 6 grams) on the rep lever, plus no binding at the bushings or balance rail hole, do the following:
Check the condition of the slot for the repetition spring. If it is grooved or dented, the spring could be getting stuck in there, unable to slide freely. To fix it, burnish the heck out of it with a piece of maple, such as a sharpened hammer shank. Also review the shape of the curve on the end of the rep spring contacting the slot. I had a different, non-Steinway piano with this problem, and the rep springs had a really tight little radius on them. There was only a tiny part of the spring in contact with the slot; hence the spring dug a hole. I took a round-nosed plier and widened the radius to prevent it from digging another hole in the slot. Then lubed it with graphite from a pencil.
If the slots are fine and/or this doesn't seem to fix the problem, it could be that a smaller diameter rep spring will work better. Sounds counterintuitive, no? When we check this aspect of the regulation, we watch the hammer rise on release. But this doesn't tell us the most important thing, which is whether the jack has reseated itself under the knuckle. It's completely possible that by weakening the spring in order to satisfy the requirement of a slow rise on release to avoid that bump at the front of the key, there won't be enough tension in the spring to move the jack under the knuckle. The slower you need to make the rise on release, the weaker you have to make the spring. Et voila, hammer sinks below the rest of the hammer line and the key will not repeat. A smaller diameter spring allows you to ratchet up the tension to reseat the jack, without getting the annoying side-effects of a hiccup at the key and a bouncing hammer.
The test for the mismatch problem is easy: assuming this is a problem in the low tenor, take a wippen from higher up in the action that will have a smaller diameter spring. Regulate it and then test it by releasing the key very slowly to see if the hammer sinks down. Torture it a few times. If that fixes it, then you'll need to get some smaller diameter wire rep springs and pin them in. (Or use silk cord, whichever is appropriate.) This can be one of the more tedious tasks we're required to do, but you shouldn't have to do more than an octave's worth.
Margie Williams
pnotuner@pacbell.net"We, the willing, led by the unknowing, are doing the impossible for the ungrateful. We have done so much for so long, with so little, we are now qualified to do anything with nothing." (Unknown)
Original Message------
I've got a four year old B with a very similar sounding problem that has been really tricky to nail down. The only way I've been able to replicate the problem is using very fast repetition with hard blows. The affected notes will eventually fail with the shank resting on the rest felt while the repetition lever is completely compressed and unable to lift the shank to reset the jack. Just sort of binds up there, although everything looks perfectly free to move with all the usual regulation points optimized.
I'm pretty sure this has to do with the rest felt being too low in relation to shanks with the blow distance that seems to make sense for the rest of the regulation. I have yet to completely solve the problem, which I think will involve thicker rest felt. I improved it by increasing the blow distance (lowering the hammers) until I had barley enough after touch, but it makes me nervous! The key dip is right where I'd like it to stay. I've heard of this happening, but never had to deal with it before...
Good luck! Would love to hear what others have done to fix this!!!
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Scott E. Thile
Piano - Instrument Technician
Murray State University