Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum Key presses “bottoming out” on percussive playing

tl:dr: Key presses “bottoming out” on percussive playing - replace front rail punching(s)?

I am not a tuner or repair person (apologies), though I do occasional work on my instrument and vigilantly maintain the Dampp-Chaser system, but have a technical question I can’t answer, so am posting here.

My Yamaha C6 was manufactured 2002 and I’ve played it vigorously for nearly 20 years now, but recently it developed a problem and I’m stumped. When I hit a key hard it feels like it’s “bottoming out”—as if you had a water bed with too shallow a frame, and elbows hit the frame floor, that kind of thing. I have never experienced this with any piano (I’ve been playing almost 60 years), but I do know my C6 intimately, so when a few keys started doing this a month ago, I freaked and was puzzled. It doesn’t happen on every key (yet?). So is it just the front rail punchings wearing out over time? Is that the sort of thing that would cause the normal "cushioned landing" sensation that every key press is supposed to have to start to vanish on certain keys? Or something more complicated involving the hammers and/or action?

I will probably pull the action tomorrow and swap a few punchings from the top or bottom (keys I never hit hard) into the middle to see if that fixes the worst keys (a few right above Middle C, especially E and E-flat). If that immediately solves the problem, then I just order a new set of punchings, right? I’m thinking Wurzen, or the ones that Howard Piano sells, or perhaps even Yamaha if I can afford it. (There's one kind that's only round on one side, with a straight edge on the other side; that's too spooky.) Runs about $1500, right? I’m not trying to stiff my tuner or anything; I would probably bring him in afterward to regulate everything. But he had a death in his circle recently and I don’t want to contact him just yet.

I am pretty sure it’s not a problem with the user’s brain, that being me (neurological or arthritic), as I went to a Yamaha dealer today, played almost everything they had, and didn’t experience the problem with any instrument there.

But I'm going nuts and have to get this fixed asap. Playing is not enjoyable anymore.

Thanks for any help!

Yamaha C6
Manufactured 2002
Dampp-Chaser installed
One main owner
Owner (me) has played 60 years

It could be that the keyframe has warped and needs to be fitted to the keybed. But first, make sure that the cheek blocks are screwed in tight.

The Wurzen punchings tend to be more firm...

Let's back up a moment. On a note that feels "fine" can you depress the key very slowly while watching the hammer rise and notice how close it gets to the string before the jack trips and the hammer falls a bit? Then repeat on a note that doesn't feel right anymore and see if there is a difference?

Just trying to get a bit more diagnostic information for us to consider options...

Ron Koval

It struck me that there is another cause of this feeling which is common in older Yamaha grands, and that is the damper stop rail getting pushed up. Press and hold some keys, and then lift the dampers on the keys that you are holding. If they lift more than a 1/16" or 1.5 mm., the rail needs to be adjusted.

Check the easy things before the difficult things!

Another option under the "easier" column is something getting under the keys and providing a stop before the punchings... I recently vacuumed up pounds of cat or dog kibble that a busy rodent had stashed under the keys!

Ron Koval

Greetings,
This may be a regulation problem, and I don't think swapping punchings around is going to do much. You have played it for 20 years and when was the last time it was regulated? If felt compression has allowed any lost motion, you could be grabbing the hammer tail with the back-check on a percussive blow. This will feel like the key's motion has been stopped, (it has), and eventually, something will break. It is common that a DIY attempt in a piano action increases the cost of remedial efforts by a trained tech.
Regards,

I did once run into a case where a mouse had chewed away the front rail punching since the last annual tuning. A coin dropped between the keys has also produced interesting tactile sensations.