dry winters versus pin blocks and old-style tuning pins

Everyone knows that dryness and heat increase the risk for cracks in harpsichord soundboards. The reason is to be found in simple cabinet makers’ lore: in a harpsichord case, various elements are glued tight together with the grain in different directions. Shrink and expansion thus cannot happen altogether freely, and if the tension in an area exceeds the sturdiness of the material at that spot, a crack will form.

A humidifier helps to keep the effects at bay, and tensions generally stay under that critical level. Some cracks, I should add, are also not very serious (others sure are). After years with either ineffective, or noisy or otherwise unpleasant humidifiers of various systems, I am now using two different sizes of Venta humidifiers to keep the whole house harpsichord-friendly (see also this post).

However, cracks are not the only thing to worry about. In September, I borrowed a colleague’s harpsichord for a concert in Kristianstad. When I tuned, the historical-style conical pins in the entire bass absolutely did not hold – I had to put shims of hard cork into their holes and hammer them down very tightly (it was quite a show, since the other musicians for a while didn’t know what I was doing).

The owner told me that this problem only arises at certain times, and hence might be seasonal; also, the harpsichord had gone through a complete revision before it was moved from Holland to Sweden and he could not understand why it behaved like it did.

I have a theory. During the first winter in Sweden, I guess, the pin block probably shrunk a good bit (winters in Holland are in average not nearly as dry as Swedish winters). The conical tuning pins would have stayed in their place, effectively widening the holes in the shrinking block. Come spring, the block expands, and all of a sudden, the tuning pins get loose. Next winter, they get tight again and for a while there is no problem.
Of course, I have not been able to thoroughly check the material of the pin block and its state – it may have been too soft from the start, or perhaps there are some invisible cracks. I repeat, my analysis is just a theory. But the risk alone that dryness would influence the basic usefulness of my instruments makes me extremely fussy with my humidifiers.

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