[pianotech] tightening balance hole was Bouncing Bostons

[John Delacour]

At 18:50 -0400 1/8/10, jimialeggio wrote:

>  JD,
>
>The key to making this work using hornbeam or maple or any hardwood, 
>is that there must be no play in the finished hole...any play at all 
>= annoying clicks.
>
>Since the key pivots at this hole, the hole cannot be perfectly round.
>
>In a hard wood you can help to minimize how "out-of-round" the hole 
>has to be by minimizing the depth of the hole. In quartersawn hard 
>maple that means 1/16" (1.5mm-ish)hole depth.  However even with 
>that minimal depth, I still have problems managing the necessary 
>front to back unihibited movement without introducing noise 
>producing slop in the hole.
>
>Any comments on what I may be missing here.


I think this was all discussed in the thread I mentioned and I'm loth 
to go over it all again so soon afterwards.

The fact is that many good quality pianos from the past do have 
hardwood inserts for the balance hole, they don't make a noise and 
they don't get ovalized.  The job I did on the Steinway D gave me no 
problems -- no pull on the keys and no noise.

As to the hole needing to be "out-of-round", I simply don't follow 
you.  The hole may be venturi-shaped or funnel-shaped but at the 
level where it pivots it is round.

The slightest amount of oblongation will produce knocks, whether 
audible or not, and these knocks will slowly but surely compress the 
wood, leading to haevier knocks and more oblongation.  The softer the 
wood, the worse the long term prospects.

JD