Keybed design

How does Bosendorfer and Estonia construct the keybed? And when comparing quality between pianos, does anyone look underneath the piano. I am very happy with the sound and everything else everyone says about Estonia (studio 168 about 4 years old, ABEL hammers) however, the undercarriage appears somewhat unfinished. Do other manufacturers spend more effort here. (this can be especially important if the party gets rocking and I windup under the piano.)

Most piano mfgs don't finish the underside. To my knowledge, Charles Walter does the most here. The under side is finished as if it was to be publicly viewed, with the maple braces finished and clear lacquered.

The only other one I remember from my piano hunt was M&H, which uses rough cut belly braces, then simply spray paints them with a heavy layer of paint. Oh, I do recall a picture somebody posted here of a big Bosie, which I think had clear finished belly braces which were painted.

I wouldn't buy a piano based on how it looks underneith. I don't know about the keybed, the only ones I know about are S&S (mortised planks) and CW (lumber core 10 or 12 ply).

Dan

Now that I think of it, if a piano is going to wind up "on stage," then the audience in the front rows (or those walking by stage front) will see the underside of the piano.

Click on my home page to see the underside of my piano. I think it's very nicely finished. But as Dan said, I wouldn't judge a piano based on how it's finished underneath.

Derick

Wow! What a beautiful piano Derick! I have the same music desk lamp and I love it.

My Estonia is painted very similar to your piano underneath but it is not "finished" with the same smooth final finish as the rest of the piano. I could not tell if your is polished from the photo. Is it polished like the rest of piano?

I agree with your statement about not judging the piano based on how the underbelly is the finished.

Mark

My real question was to generate some discussion as the the advantages (disadvantages) of having the Keybed part of the case construction as with Bosendorfer and Estonia. All other pianos fasten the keybed from underneath the case. Does "one piece" construction offer a better piano? (since I was standing at the time of the purchase, I did not base my decision on the undercarriage, Rich G simply did his normal superior job, and the Estonia spoke to me (maybe Rich could offer some wine tasting.))

The primary function of the keybed is to locate and support the action. Obviously it also (usually) has a couple of legs attached to it as well as the pedal trapwork and lyre. To serve all of these rolls it must be structurally sound and dimensionally stable. Historically, keybeds were build using some form of “breadboard” construction or “frame and panel” construction. That is, they were constructed of solid wood beams and put together in such a way as to allow these beams to swell and contract with changes in local relative humidity without upsetting the bedding of the action overly much. The keybeds of some pianos are still built this way.

A newer and, I think, better construction is the solid, cross-laminated panel. These keybeds are made up of cross-laminated veneers of either softwood or (usually) hardwood. In the U.S. this is usually poplar, basswood or alder. The faces are usually hard maple. As with the frame and panel or breadboard keybeds end-grain hardwood dowels are inserted at the wear-points where the keyframe center-rail glide bolts rest against the surface of the keybed. These keybeds are both stronger and dimensionally more stable than their predecessors.

Now, to your specific question; how is this keybed attached to the rest of the piano? Most, if not all, keybeds are attached to the lower side of the rim and the bellyrail in some manner. Structurally, it makes no difference how it is attached as long as the attachment is perfectly rigid and mechanically sound. With few exceptions keybeds are attached using a combination of glue and screws and/or dowels. As long as the glue joint remains intact how this union is made is of no practical consequence. Arguments both pro and con can be made for all types of construction but they all serve primarily to confuse rather than illuminate. They may well have meaning to the builder but are utterly meaningless to the musician.

The exceptions to all of this are the several pianos that are now coming into the country with keybeds that are simply screwed onto the rim and bellyrail. Or are assembled with so little adhesive as to be of no practical benefit. This construction may well have a detrimental long-term affect on the overall structure of the piano. I doubt that any of the pianos in your price range are so constructed.

Del

Thanks Mark. The underside of the piano doesn't have the high-gloss finish the rest of the piano has, but it is *perfectly* black. On my last piano they had kind of done one quick coat of black on the supports and underneath the piano. Some parts had less paint than others.

Oddly enough I find myself crawling under this piano just to marvel at the work they did. Then I remember that's there's 1250 pounds perched above me and I decide I've looked long enough. The irony of the piano I killed myself to buy is the piano that kills me! Yeah, I know, I'm weird.

Derick

Thanks Del. Since I am an engineer, I appreciate the Technical response. As a piano player, I am just glad it sounds good.

I imagine, the higher the quality of piano, the better finished the underside of keybed will be.
Many of the German makers spend extra time making even the support beams look nice (with colour and smooth sanding). Some continue their veneers and polyester underneath as well.

Del, thank you for the very illuminating post.

Got a follow up question:

With regards to what farleydog wrote about "having the Keybed part of the case construction as with Bosendorfer and Estonia"... how is that differ from any of the methods you described?

Thanks.

Ax - here's how it was explained to me (laymen's terms = salesman-speak).

Only Bosendorfer and Estonia embed the keybed into the sides of the case. All other keybeds "hang" off the bottom with screws, glue, etc.

When I asked why this was good, I was told "maybe better structural integrity."

Not saying it's true, just what I was told.

Axtremus,

Del hasn't answered your question yet so I'll jump in.

The rim rests on the keybed in most pianos. In the Estonia (and Boesendorfer) the keybed is narrower than the rim and built into the rim. Therefore the rim is deeper at the keybed area. This explains the slab-like styling of the Estonia when viewed from the side.

Estonia says it costs more to do it this way.

Estonia claims that it is stronger. My technician noted that it is not dove-tail construction and concluded that it confers no structural benefit.

On the other hand, my technician says that the rim in pianos tends to contract, not expand, and this was observed when the pin block was absent from a Steinway for a period of time. The dowelled pin block would help keep the rim from narrowing, but I would think that if the keybed were built into the rim it might also help. That is my own conclusion, not my technician's.

As to the issue here, I believe that everything underneath, including the keybed, is pretty smooth on my Estonia, which was built in September 2002. My technician believes the keybed could be MDF, while I guess Baltic birch. The keybed on the older Estonia may be different from mine or the current ones.

Good construction technique is to finish both sides of a piece equally, so that both sides absorb moisture more or less equally. That avoids warpage. The top of a keybed is usually not finished, so the bottom should be only lightly finished.

I haven't looked at the bottom of either of these pianos lately, but I suppose the keybed is fastened in the usual way. It's just that the bottom of the rim extends to cover the outside edge.

farleydog your first question is this:

The first sentence contains the only "technical" question in the entire post. You then proceed to talk about frivolous things such as an under-finished under carriage and piano piles under your piano.

After a few replies you post the following stating what your "real" question was:

Finally, when you get a "technical" answer that suits you and you finish up with this:

Let me strongly suggest to you, and anyone else who wants a highly "technical" response their posts, phrase them indicating exactly what you are after. Us non-technical jerks will answer the sections of your precious questions that we can answer. If you don't want to hear such drivel, then perhaps you should not talk about piano pile-ups under your piano.

Sorry you had to wade thru a bunch of crap before you got an answer from a piano designer.

Derick

Thank you all for your responses to my query. Much appreciated.

While it is probably more expensive to build this way there is no evidence that it is any stronger.

A rim can do any number of things once it is built. Especially those rims — such as the Steinway rim — built with no crossbanding. An increasing number of rims are built using crossbanding and these are proving to be much more stable. Since there is no particular advantage to not using crossbanding I’m not really sure why there are still holdouts. But there are.

I doubt the keybed of the Estonia is made of MDF. Although, if the structure were suitably designed and braced this material could probably be used effectively. I would guess, however, that the keybed in your piano is Baltic birch plywood.

Del

I haven't been able yet to read this whole thread, though the keybed discusion IS of interest to me. Just thought I'd mention that the "undercarriage" of the Fazioli is finished to a very high glossy light colored (ie. not ebony) shine. I've only crawled under 3 or 4, but they are all pretty good looking under there. No rought cut grain or anything. I don't suppose it has any effect on anything but the reputation of the piano.

Bob

It's a reflection of how they (the manufacturers) view their instrument's quality. A work of art isn't truly finished till the artist feels totally satisfied with the final product. The better the piano, the more refined finishing underneath. It's pride of manufacture. And it costs alot more too.

I once had a customer who created a mirror floor under his grand so he could admire the beauty of the craftsmanship. Had it lit underneath, so you could stand next to the piano and look down. It was indeed a talking point at parties.

Funny you should mention lighting under the piano. I haven't thought of putting a mirror underneath, but I have been trying to figure out how to light it up from underneath to increase the "dramatic" effect at night.

Derick