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I've tuned this small grand 5 times since it was new in 2009. Each tuning has been a fight for stability and all but one has been a pitch raise. Yesterday was no exception, so I pulled the action and was able to pass a soundboard cleaning steel between the pinblock and plate flange nearly the whole length.

No wonder it's unstable, the block is held by the screws only, having no plate flange contact to help support the string tension. The block is rocking during tuning. This is not the first time I've seen this in this maker's pianos.

I would suggest to piano makers that having good contact between the block and plate flange is a good thing, and is a must have when you build a piano. In this day and age, fitting a block to the flange in a mass produced environment should be very easy. There is no excuse for a rocking block.

I'm finding the quality of tuning pins as more of an issue. A soft tuning pin in a tight block does not work. I'm guessing its poor quality control from the tuning pin manufacturer.

They aren't called "PSO's" for nothing.

Or "POS's". :-)

Most of us work in people's homes, so we call em PSO's. We do that so we won't make an embarrassing verbal slip-up.

The maker recommends shimming the gap between the pin block and plate flange.

Did you ask the maker why that wasn't done at the factory. Was the "shim guy" off that day?

Bob, you have not identified the make of piano. The question I have here is whether or not it has plate bushings for the tuning pins. Pianos like Yamaha and Kawai (like many pianos)have plate bushings, and they argue that a pinblock does not needed to be mated to the flange because the bushings along with the plate screws offer sufficient support to the pinblock to create stability. I'm not convinced that this is the case, but that is the argument.

Hi William, This piano does have plate bushings, and I saw that mentioned in a PTG thread recently. I don't subscribe to that theory that plate bushings are enough to stabilize the pin block when there is no flange contact. I can crush a bushing pretty easily, as can a tuning pin under pressure. I also don't agree with the assertion that mating just the top of the pin block to the flange is enough support. When that is done, the block can pivot.

Given the tension of strings that pin block has to be as secure to the plate as possible. I'm not an engineer, but to me it's simply common sense.

5 tunings in 6 years mean the strings are no longer stretching - so the only plausable reason for the instability is pin block movement. The instability is as bad today, as it was years ago. I can get a tuning out of the piano, but the instability is obvious to me as I tune it.

No doubt it's better for the pin block to mate with the flange but isn't the main thing for tone as well as tuning that the 30 odd screws going holding the pin block to the plate are tight?

Mind you, the piano I have in mind is 105 years older than the offending 2009 baby grand in question.

Anybody want to propose a test alternative to tuning instability to prove that the block fit (or lack of) to the plate flange is the problem? Is tuning instability proof positive in your opinion?

Kawai, at least in the past if not still, uses hardwood "Plugs" not plate bushings on their grands. The fitting to the flange has a rather noticeable gap but the piano holds tuning just fine. The standard plate bushings from the supply houses would not accomplish this level of support. I have replaced a few Kawai blocks in the past but always do a careful fitting to the flange since I have no problem doing so, and I really don't want to re-invent the factory method of making hardwood plugs and drilling the new block with the plate installed.

Since the brand of piano is not mentioned, I am 'assuming ' it is NOT a Kawai.

5 tunings on a piano new in 2009 is not a lot of tuning. I would expect the tuning stability to still be somewhat of an issue. My curmudgeonly thoughts.

I always wonder why piano makers who insist that having the block contact the plate flange is not needed feel the need to HAVE a plate flange. If there is no need for the block to fit the flange there is no need for a flange.

The plugs I buy are somehow hard, beech, may be. Could be harder if that is the intent but still they seem to shim the pins correctly (which I do not like so much)

Ed,

it's probably at the direction of the marketing department. Can you imagine the rhetoric from the competition, "Brand XXXXX is so cheap they don't even have a plate flange."

No....It's not a Kawai.....I would imagine a plate flange adds stability to the plate, helping prevent the plate bowing higher or lower in the middle. A rocking pin block has a different type of instability than stretching strings of a newer piano. The initial stretching of strings masked this issue on the first two tunings. My suspicions on the rocking block began with the third tuning. This is a rocking pin block.

I've just realized = The tuning pins on this brand of piano tune much like many Kawai - the pins are small, flexible, very tight, and can be sticky. So if the strings are forcing the pins against the bushing.... 30,000 pounds total tension divided by 230 or so tuning pins = 130 pounds of tension per pin against the bushing if the plate screws fail to hold the pin block, and the block doesn't contact the plate flange.

No wonder I have to flex the pin away from the string (towards me in a grand) to turn the pin in the small increments I need. All of this makes sense. No wonder the tuning pins on some brands are difficult to manipulate - the tuning pins are pressing against the plate bushings with 100 + pounds of force


Am I off base here?

I've fitted every block I've done, and drilled the holes at 7 degrees angle, so the pin will contact the bottom of the plate hole only when under tension. Friction against the plate is minimal, and the block is secure and unmoving.

These Asian blocks are moving, creating addition friction at the tuning pin due to string pressure at the bushing.

Bob,

I think the tuning pins are not meant to hold the pinblock.

I think this would not be a good idea.

If the screws are not enough to maintain the pinblock in position then let it rest on the plate's flange.

No, the pins should not hold the pinblock - The plate flange should hold the pin block.

Sorry, I'm afraid I did not understand what you said in your previous post:



Doesn't that means the tuning pins are holding the pinblock via the tuning pin bushings?