Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum Pin block not contacting plate flange

Bob, to me contact with the plate is to be avoided. (I hear you it is very small there) It can be seen on some Steinway repaired with stronger pins, when the plate hole have not been "reamed", often there are pins that touch the plate, and they are not as stable s the others, not as much set.

It can create noises, also I was said.

SO the hole is usually enlarged, some even create a pronounced conical aperture in the upper portion of the plate hole...

Then less risk of contact.

regards

PS pins "small and flexible" can be an advantage but small and soft, no, flexible mean "resilient" in my reading of your words, if they flex without much springy behavior, they are a hassle. (lets see Boston verticals in that category !)

BTW I have a box of "Japanese" pins that are shining, without being nickle plated.
I cut one in 2, and it looks like stainless steel , not frankly a springy metal.
That may be the cause of those trouble.

Klinke or Biene are in a somewhat soft steel (non tempered) but they get springy when tension is applied.

On sale : a box of shiny tuning pins !!!

Ok! I've got it now. Sorry for the confusion.

The pins are resting in the bushings, which in turn push on the plate and part of the strings's pull is going also to the pinblock which is held by the plate by the surface in contact with the plate.

Anyway, I think it can produce some tuning unstability. I have always believed the pins should never touch the plate when there are not bushings.

I thought the bushings were there to center the bit when piercing the tuning pin holes in the pinblock and were not meant to hold the pins.

the underside of the bushings are firmly in contact with the block, that creates a precise fit , and it may lock the plate in position at last in that direction.

I hae seen Steinway fitte with pin bushings, which is not a good idea, part of the friction is lightened by the bushing, and the pin cannot be stressed as tightly/securedly as when there are none.
The official theory said t-hat they are there to help supporting the pins, avoiding flag polling, , less stress on the block, but this is not really interesting, once one knows how to leave the pin stressed the same than the wire, without busching the tuning is easier, an the pins are more active,acoustically, not 'damped" by the bushing.
The block then can also be "active" hence the case.
(hence a more sonorous piano)


Looks like the "circle of sound" from Steinway many techs like to laught about on forums as they know so much better !!!!

once experimented the rise in tone that happen on any piano with corretcly straightened and stressed pins, that "marketing gimmick" can be appreciated differently.

Same happens with the ability of the keybed to radiate sound.
Some makers do not think about that (Fazioli) and the keys are less tinkling, the pianist hear the tone created a litte far from him, which is less pleasing, a piano is not a typewriter, but an acoustical instrument, even if the walls of the case are there to be massive and avoid losses, the tone is warmer when allowed to circulate elsewhere and not only returning into the soundboard, as I suspect it can saturate it sooner (the circuitry is up to the plate in some pianos)

the absence of cutoff bar on the left part of the soundboard creates also an escape circuit for the tone that make it more forgiving for the pianist, at the expense of a slightly more barrel toning output. there are too much other problems create by that one so it may be better to avoid that, but leaving some path for the tone is certainly a good idea.

Part of that may be in the resonator of M&H and that certainly filter and modify a little the output too.

I installed a treble tension resonator once, an could hear it in the tone, a metal composite due to the tensed metalic part resonating.

Sound waves are passing everywhere, it is why an isolate room to play without making noise outside loose much of its efficiency with the slightest aperture, as a heavy door that is not jointing anymore, or a hole for climate control, if no specific goodie is installed there.

I think the "cross" of the plate upon the pinblock and inner wall is sening much waves into the plate, hence the easily metallic sounding of Yamahas with their lighter plates (spherical iron, less damping) This is giving the tone a colorataion (more or less present)

Olek, those Japanese pins you have, are the threads blued (coated with a blueing agent) ? The reason I ask, is I use blued thread pins when stringing, and never have sticking issues or spongy issues.

no , the threads are shining, not blued.
I will post a pic eventually.

They feel soft when tuning (spongy)

I suspected that.

I tuned another of the same brand this morning different model (the next model up in quality) - new in 2009, raised pitch 25 cents in 2010, and raised pitch 25 cents today. This one came up normally for this brand and model. It was more stable than last weeks subject of this thread. There was 40% pin block contact with the plate flange - low bass and high treble had contact and there was a bit of contact at the bass break. So in this instrument, some contact seemed to be enough to prevent the block from rocking.

There was evidence of bushings crushed towards the rear of the piano, as if the block had moved with the string tension a bit, but a few bushings were narrow to the right of left side, which indicates off center holes during drilling.

The pins on this piano felt really good - not too tight, not sticky, not spongy - very nice feeling.

If you make an accurate cross-section drawing of the original configuration of these pinblock/tuning pin designs you'll find that tuning pin contact at the bottom of the hole is pretty much inevitable. And, I think, intentional.

ddf

Yes, Del - I fit a block to the flange, screw it in, and use a tuning pin punch, resting on the rear of the plate hole, at a 7 degree angle to mark the center of the holes. I remove the block, and drill it on a drill press, with the base at the 7 degree angle - compressed air cooling the bit. When installed, the edge of the hole is 1/16" - 3/32" (sometimes 1/8") from the plate. Once strung and under tension, the pin seems to be very close to the bottom of the plate hole, but not with a great deal of pressure. The pin never touches the top of the plate hole due to the backwards angle.

I have to wonder if excessive pressure pin to plate though bushings is causing overly tight, sticky, lousy feeling pins. Many pins turn better when I pull the pin away from the front of the plate hole plate before turning.

I am going out today, to install shims between the block and plate flange on this piano, under warranty. I'm quite sure the shims will improve the stability.