List, > I would also describe most of my repinning the same way, > with the growing > exception of new Steinway hammer shanks and underlevers. > Some, over the last > three years, have tightened up after the sale and had to be > reamed. This is very common, and there may be different ways to look at it, but it is caused by instable cloth. In one manufacturer's case the problem was in the way the felt was being inserted into the hole, especially combines with no burnishing. Factories which burnish the bushing for final fit very rarely will have tightening problems. > I pin these pianos to be right on from the get-go. > Usually 5 swings is a > central aim, but I will let them go 7 if the weather is dry. Ed, I find swings to be a very vague spec. Is this in the center, bass or treble part of the piano? > >> And I sure wish action makers would > revert to starting off with 19 centerpins, instead of 20.5 or so. >> > > I was told that the automated machinery used to drive > these pins in the > parts requires the larger sizes to reduce the bend and > failure rate of the > machines. The machine assembly explanation is partly true, but there is another reason for larger pins, especially in hammer centers. These manufacturers are intentionally making a thin bushing, and the larger pin combined with thin bushing gives an optimum friction:firmness ratio with good cloth. Using a #19 pin could be done with a smaller hole and thin cloth, but this creates other problems in manufacturing. The core issue is how easily the pin compresses the cloth fiber, and with the densest cloth available the smaller diameter pin can distort the cloth fairly easily, giving less solid control of the hammer. I agree that long-term serviceability is better if the pins start small with a thick bushing, of course. I don't feel that action centers should have to be repinned too many times in the life of the parts, though. If the manufacturer screwed it up and the parts tighten or loosen in use, then one careful repinning should last pretty much as long as the shanks / knuckles do. Extreme humidity conditions might change this, but the repinning should be done (as Fred Sturm mentioned) with the humidity conditions in mind. So parts starting out with #20.5 pins can progress up to #22 and perform well - that is 3 repinnings, and if the piano is pounded in a practice room or studio so much as to need more than that, the knuckles, hammers and shanks themselves will probably need to be replaced anyway. Don Mannino
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