Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum Blüthner grand 13313, pinblock damaged

I was called to repair this Blüthner grand, serial no. 13313.

It has a whole section (the low tenor trichords) of the pinblock damaged.

I wonder if it is possible to repair this section with epoxy.

The owner is a piano lover. He owns 4 pianos (3 grands and an upright) and he says this one is his favorite. He has 4 children who study piano.











The piano is tuned to 435 hz and only this section of the pinblock (11 unisons of it) is damaged. The rest is fine and at pitch.

For instance I have realeased tension in this section.

Any thoughts? Help appreciated.

My first thought without more information would be to remove the pins, rout out the entire section and epoxy in an insert made of real pinblock material. Shape it so it blends in and redrilled and insert new pins.
Possible shape the insert first and drill outside of the piano before epoxy it in.
You'll need to locate the holes without being saiid.

Gadzar, I can't answer your question I am afraid, but I am interested in this piano because it is of a similar age to my own Bluthner grand. I would love to see if the plate design, bridges and stringing are the same as my piano or if there are differences. Is there any chance you could post a picture of the inside with the lid up? (To show the full plate, bridges and strings.) I would be very grateful!

We rebuilt a Bluthner that looks structuraly quite similar to the one pictured. There is a thread on it, if you are interested. It's block had failed in a similar manner. The block is made of three layers; a bottom plank of oak, a main block of maple, and a capping layer.

The bottom plank extends forward to the edge of the plate flange, and is secured to the plate with multiple screws from above. As the plank does not actually touch the plate flange, its primary purpose, we think, seems to have been to resist the downward portion of the twisting force generated. We found that the screws were quite short, and barely anchored themselves in the wood even when new. This meager support peters out toward the middle; right where the twisting force is the greatest. We suspect that it was the failure of this support that allowed the main block to fracture and flow.

If the underside of your block is bowed down near the failure, then the same thing has happened here. Even if you rout in a new section of block, which sounds interesting, the support structure will still be compromised.

In rebuilding, we addressed the problem by installing a full-length, 3/16" steel plate apron on the underside of the block. The wood screws were replaced by machine screws, and threaded into the apron. Something similar, might be a good idea if you do work in a new section.

I would love to know if the routing in works.

Sorry for the delay.

I'm afraid routing out the entire block section and epoxy in new pinblock material is out of my skills.

The piano is 250 miles away.

I was hoping filling with epoxy and redrilling would solve the problem.

This is not a job I would want to do on-site. The piano moving expense would probably be less than the extra expense of commuting to the site.

I would also recommend taking the tension down on the whole frame slowly and in steps.
Taking only 1 secion down, as mentioned, can crack the frame due to unequal stressing.
I have actually seem this.

Regards
Bernt

Before expressing any thoughts it would be handy to know what the condition of the rest of the piano is like.

Wow Craig, I've seen your "Blüthner 5694 Underway" thread. It's a wonderful work you made on it.

I'm not a rebuilder. I'm just a piano tuner who makes some little repairs.

I guess I'll pass on this one. What I can do with this pinblock won't solve the problem.

Thank you all for your answers. I really appreciate your help.

Good for you! This is not the sort of job to start with, especially when it is someone else's piano.

Yeah! I've also passed on the Centennial D.

Too much for me.

Gadzar,
Is that Centennial available?

Craig

I agree with BDB. Good decision to pass on this one. We do quite a few pinblock panel jobs where routing out is involved, and it's a repair I would never do on site. Too much of a mess, too much noise - plus to do it right the strings and plate need to come out of the piano. Not something the owner is going to feel comfortable having done in his house.

If you ever do want to try the procedure, find a practice piano and do it in your shop, where you can learn from your mistakes. Chuck Behm

Yes Craig, it is for sale.