Replacing the Pin Blocks

There are century-old pianos with pin blocks that are performing like new blocks: good tuning pin control, adequate or even superior torque. It is a joy to discover and service such instruments. More common are pianos both old and not so old where the pin block is marginal or failing completely. In these cases, replacing the pin block is necessary. It is always a major operation to replace the pin block. The piano must be destrung and the cast iron plate removed. Upright pianos and some grand pianos are constructed in such a way that the pin block is integral to the structure of the case so major deconstruction is needed. Some, usually lower quality, grand pianos the pin block is easily removed after the plate has been pulled from the case.

Fitting a new pin block is time consuming but extremely critical. I always fit a new block to fit the plate without the use of epoxies or other shortcuts. As with all manufacturing, piano and otherwise, the search for time and money-saving processes is constant. If the factories of both high and lower quality pianos think it is necessary to fit a pin block without resorting to epoxies, then how can I justify such methods? I used to need several days to fit a block. I’m faster now with more experience and better tools, but it is exacting work and must be done carefully and correctly. Since the pin block is so critical, and so hard to get to, it must be done in a way that means not having to go back to do it over.

After the block is in the piano, the re-gilded plate is reinstalled. This also is exacting work. The fit of the strings on the bridges depends on the plate being properly located both fore and aft, left and right, as well as up and down. A few thousandths of an inch can make a huge difference and affect tone as well as action function.

Drilling the block to receive the new tuning pins comes next. I always use a double pass. The wood is so dense and hard keeping the drill bit cool is a challenge. I use a constant flow of chilled compressed air but even that doesn’t succeed entirely. The answer is to first drill the holes with a slightly smaller-than-desired hole and then make a second pass with the proper bit that removes only a tiny amount of wood. This makes possible very consistent hole sizes and predictable tuning torque.