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I have this feeling when the piano is complete the bass will be heart stopping.

+1

Craig,
Did you complete the restoration of the Bluthner? If so, any thoughts/information you would like to share.

Carl,

Finished? heavens no. But we did just get the board remounted.

https://plus.google.com/photos/105412259108667869462/albums/5941003537049872049

I was never really worried about the board, beyond figuring out how to get it out. The real adventure in this piano is going to be the pinblock. The block did not fail bacause the wood around the pins cracked or anything like that, the block failed because every screw that went through the plate nad into the block failed, and the middle of the block twisted down. When we removed the tension, the body of the pinblock returned to straight(straight enough). The majority of the distortion is in the bottom board, so I am thinking of replacing only the bottom board, along with splicing in some new maple pinfield cap where it was smooshed against the plate. this should clear up any clearance problems with the action. Beyond that I am contemplating replacing all of the failed screws with machine screws and t-nuts set flush in the bottom. Its not original, but it is the least intrusive means to add stability to the system. Any thoughts? Anyone?

https://plus.google.com/photos/105412259108667869462/albums/5941064749641705585

Be well

I don't envy your task Craig. Is it possible to get a casting of some sort to replace the board under the pinblock with, and bolt through both the strut and pin-block into machine screw threads? Sort of a cast plate for under the pin-block to stiffen the whole structure against the rotational vectors.

Craig,

Not that I'd ever try to give any advice... But I am fascinated by the whole thread, and I'd like to understand the original design better, in terms of how much of that torsional down-force was meant to be borne by the plate or by the bottom board (and rim). My apologies if these questions appear trivial:
1) Did the old screws go through the block and into to bottom board?
2) Was the pinblock glued to the bottom board?

Hi Craig,

With a rebuild like this, how much are you trying to stick to the original design, and how much are you willing to deviate from it? For example, the original pinblock seems to be on using 2 or 3 plys. Would you build a pinblock of the same construction, or would you install a modern pinblock with many plys? In terms of the torsional stress which destroyed the original pinblock, could you take any design cues from later Bluthners which probably solved that problem?

Regards,
Andy

Ed,
We have had discussions about a steel plate a la Hardman keybed. The t-nut idea is a minimalist aproach, their strength only radiates a small distance. Their positive quality is that they have a great deal of thread to hold with. I don't think it would be good to replace the entire bottom board . I think that the block body needs to actually be glued to something. I'm thinking that the apron should be as thin as will reliably hold the threads under full tension, but I would hate to under estimate those rotational vectors.

Mark,
The short screws in the webbing go into the bottom board. But they only penetrate about a half an inch. They don't seem to have held much for long. The long screws go through the struts and go into the block body.

Yes the block body is glued to the bottom board.

It is an interesting system. There is an iron bar running through the stretcher, that I think he felt would restrain some of thosr rotational forces. Unfortunately, I think that, rather than restraining those forces, the bar leverages those forces to the front of the block. It seems that the bottom board was meant to controll forward bowing of the block and act as support for the leading edge of the block. It did well against bowing, but the screws in the webbing were just inadequate. A curious detail is how little of the block face actually touches the plate. only the top 3/4 of an inch touches. even with that, the majority of compression in the blockface seems to have come from the rotational failure.

trivial? Nah, this is the juicy stuff.

Ando,
Generally, I try to keep my ego in my back pocket and stick with the designers choice. That being said, I do have a responsibility to make as stable and durable an instrument as I can. Consequently I feel I have to do something to keep the block from failing in the same way. I just want that something to be as effective and inobtrusive as possible.

I haven't reached the point where I feel that the entire block needs replacing. If I had to, I would want to go with the original design. That would require that I find a suitable piece of maple. That might not be so easy these days.
Should that prove elusive, a block made of multiply would be acceptable. Not Delignit, I hate that stuff. Even then I would put the maple ply on the face to hide the ugly.

I would love to see some newer Bluthners, there are just none around here.

Thank you again, grain, for sharing this process with us.

I took a look at the Steinertone photos while I was looking at the Bluthner. Do you specialize in 'problem children'? That action...

Wish you were closer, so I could see some of this up close.

The problems this Bluthner shows, is the reason that design was abandoned. The rotational vectors are too large for the support structure to hold. That is why I was suggesting adding some sort of non-deformable bracing tied to the plate struts.

The new Bluthners are very interesting pianos. They have done the fourth string aliquot in a very stable way. But I wish they would not do any of that. The added weight of a fourth string and bridge pin to the bridge makes the tone thinner. The precision of the bridge pin placement is amazing though.

Hi Craig,

I've seen a couple more recent Bechsteins with the same rotating pinblock problem. Added to this Bluthner was the fairly obvious moisture issues and general glue joint failure. If I were you Craig, I'd let my ego take over. Replacing this with a similar structure is problematic at best!

The Bechstein I saw most recently could have benefited with far more screws (and some longer) in the available casting area. There was room for more screw density in the plate. I don't recall what type pinblock material it had. It was only about 25 years old though.

Having said all that, I haven't read the thread from the beginning which I will now endeavor to do. I'm sure that will explain why you chose to go through more trouble to salvage the original board than to just yank it out and make a new one. Not to mention not making new bridge roots instead repairing the pulpy stuff you are working with. I must now go forth and read. Good luck. Nice craftsmanship in any case. Great pictorial, too.

I swear I wrote "Craig" instead of "grain."

:-/

Hello Craig,
Have you made a decision on the hammers for this piano?
Thxs,
Carl

Carl,
I have only just now started to clean up the action and look at the parts. The hammers look to be original to the action parts, and they are Bluthner slant sliced. They seem to be very light hammers. #2 bass may weigh 8 grams, at most. So weight is a major concern.

My first thought would be the hammers that Jurgen sells, though I have yet to quiz him about them. Abel makes a patent grand hammer, too. Though I suspect that is what pianofortesupply.com sells. They seem to make everything these days. I just hung a set of Encore Naturals on a BB, and they made them, too.

Odd thing about this Bluthner, while they sliced the hammers from the bar at an angle, they then hung the hammers straight to the shank.

If the available hammers are all too heavy, I may have to see what Ronson can do for a light weight.

As for the rest of the piano, all concentration has been on the pin block. We have decided to go with a sheet steel apron fit to the full bottom of the block, as Ed suggested, but also let into the bottom of the plate below the agraffes. This will provide stable support for the front edge of the block for its full length, and provide something meaty for the new machine screws, passing through the webbing, to bite into. All this is supposed to happen inside the original contoures. And that will be the limit of my minimal and inobtrusive. The rest has proven to be majorly obtrusive, invasive even. But it has also proven to be necesary. We disassembled the pinblock, and we found, at its heart, that the main plank had split along the rear line of tuning pins in the two center sections. It could never have been salvaged.

So the plan now is to reproduce the block, as closely as we can, with the retrofit included, and to reuse what original parts we can manage.

Here is a link to the latest photo cashe. There is a lot going on inside one of these blocks.

https://plus.google.com/u/0/photos/105412259108667869462/albums/5963186350603739985

I'm overwhelmed...

Yeah, it sure makes you appreciate the modern full fit pinblocks for their genius of simplification.

Oh my goodness, yes.

You are a master craftsman, Craig. Thank you again for sharing what you do with us.

That is by far the most complex pin block configuration I have ever seen. I wonder how Julius contrived it.