I came across a Petrof grand yesterday ... my first experience with a Petrof. The serial number tells me it was built in 1997. It has had a Dampp Chaser since it was new, although the tank was dry and the pads tell me perhaps it is not being watered routinely.

As I was tuning, it seemed the pin block, although certainly not loose, was a little 'touchy'. As I looked closely, I saw hairline cracks all along the block. See attached photos.

[img]http://s436.beta.photobucket.com/user/do...018521709281988[/img]

[img]http://s436.beta.photobucket.com/user/do...244214012007382[/img]

This is the first time I have seen a pin block not covered by the plate. Is this the beginning of the block de-laminating or are these simply hairline surface cracking and nothing to worry about? Has anyone else seen such cracking of this nature? If it is delamination, ss the only solution to replace the pin block? Toughts would be welcome. Thanks.

Don

Probably just cracks in upper thin veneer.

The "touchy" feel may be just that it is an open face pinblock. They do feel different. I kind of like them, but I only see them in old uprights.

I also think they are surface cracks and are merely cosmetic. I cannot think of a way this would progress into delamination. It does show that humidity is not being controlled. Damage to the soundboard is the more critical matter imho.

Delamination is in the horizontal plane. These are not delamination cracks. I am also sceptical about the year of the piano. The wood veneer reminds me of a vintage pinblock and I have not heard of an open faced pin block on new construction.

Shrinkage, but that is the way pinblock cracks, on a row of tuning pins.

Petrof redesigned their models in the year 2000 so it is possible that the older ones where open, I am sorry but I cannot be more precise, other brands have an open block, and othere have no pin bushing, and I prefer them for the pin setting provided.

the pin bushing kind of lower the sensations thru the tuning lever, I also belive it damp somehow the tone, but I agree this must be debateable

Delamination occurs in the horizontal plane as Mark indicated. (Think of delaminated plywood.) It's a bit hard to diagnose unless it's really advanced. Some bulging in spots, or wildly leaning pins can be a couple of indications. I usually wait until I pull a grand action and bits of the pinblock are lying on the top of the action. Yup! It's delaminating. Sure enough. I feel very confident of making the right diagnosis at that point.

I have come across a lot of this over the years. It is the dress facing veneer on the front of the block that is deteriorating.

What it does indicate is, when at concert pitch, the tremendous downward pressure of the tuning pins against the front edge of the hole in the block. The cracking reveals that the holes are going oblong as the downward pressure on the front of the hole will be upward pressure inside at the back of the hole.

Not possible to remedy as this is the natural aging process. If tuning pins are slipping then something will have to be done to correct that.

Bösendorfer still makes pinblocks like that. I think Bechstein does, as well. Blüthner does too, although with a sheet of metal over it.

Yes and yes. I have a Blüthner with the plates, and I just looked at a 50’s Bechstein M on the Gulf Islands with an open style pin block.

Newer Petrof grands have the open face pinblock. There's one I tune that's around 7 years old that's open face. Great feel to the pins. I love the feel of open blocks.

This being a grand, the thing to do is pull the fallboard, and look at the underside of the block with a mirror, bright light, and good reading glasses.

....and this will tell you the condition of the bottom layer of the pinblock. The condition of either extreme layer of the pinblock says nothing about the state of the inner plies of wood in a modern multiply pinblock.

Only in a solid pinblock, which nobody has made for years, can examination of the topside or underside say much.

Only the condition of the block as it feels to the experienced tuner, (or maybe a torque wrench for an inexperienced tuner or one looking for ammunition to sell a repair), is a reliable guide to pinblock condition of a modern piano.

All this talk of openface pinblocks is making me hungry.