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Step 15Bench regulating: keys
All the different movements of the piano action have to be adjusted to take up variations in the parts and positions so that they all work evenly. This important stage is called regulating and happens to be missing from the online copy of Davies' instructions. Different kinds of actions have different things to adjust but first step usually involves adjusting the keys.
I glued the front edge of the backrail cloth onto the rail and stuck a cloth punching on each balance and front pin, checked to make the natural keys so the fronts and tops were square, and then used a small fine triangular needle file to enlarge the key mortises in order to make the keys all move freely, taking only a couple passes at a time before checking the key on the keyframe. I made the front mortises a little looser than the balance mortises.
In order for the regulation to be durable, and to reduce the amount of noise the keyframe needs to be fit, or bedded to the piano in the exact position it will occupy. In uprights and squares it is usually screwed down in a bunch of places so it follows the contour of the keybed. In grand pianos it usually has to move sideways when it's installed, and besides carefully lowering high spots by hand there are some mechanical methods of making it fit.
It's more accurate to regulate the action inside the piano, but in grands and squares it's cramped and difficult. I rough levelled the keys by clamping the high spots of the keyframe to a flat table and propped a straight edge on a pair of equal sized parallel blocks to either side of the front of the keys. I made the blocks so the straight edge was above the level of the keys and so when they were raised to that height they would go down a little more than necessary. The gaps between the straight edge and tops of the keys are bigger than the thicknesses of the paper punchings used to close them, so it's easy to check if they're much too thick.
I levelled the naturals, and then readjusted the blocks and levelled the sharps and each set took about three passes. You have to make sure the keys are all the way down on the pins, and for a final regulation the paper punchings are supposed to be placed underneath the cloth ones. There's a special forked tweezer made to lift all the punchings together. William Braid White pointed out that it's more rational to make large increases in height to groups of keys by shimming under the balance rail.
I glued the front edge of the backrail cloth onto the rail and stuck a cloth punching on each balance and front pin, checked to make the natural keys so the fronts and tops were square, and then used a small fine triangular needle file to enlarge the key mortises in order to make the keys all move freely, taking only a couple passes at a time before checking the key on the keyframe. I made the front mortises a little looser than the balance mortises.
In order for the regulation to be durable, and to reduce the amount of noise the keyframe needs to be fit, or bedded to the piano in the exact position it will occupy. In uprights and squares it is usually screwed down in a bunch of places so it follows the contour of the keybed. In grand pianos it usually has to move sideways when it's installed, and besides carefully lowering high spots by hand there are some mechanical methods of making it fit.
It's more accurate to regulate the action inside the piano, but in grands and squares it's cramped and difficult. I rough levelled the keys by clamping the high spots of the keyframe to a flat table and propped a straight edge on a pair of equal sized parallel blocks to either side of the front of the keys. I made the blocks so the straight edge was above the level of the keys and so when they were raised to that height they would go down a little more than necessary. The gaps between the straight edge and tops of the keys are bigger than the thicknesses of the paper punchings used to close them, so it's easy to check if they're much too thick.
I levelled the naturals, and then readjusted the blocks and levelled the sharps and each set took about three passes. You have to make sure the keys are all the way down on the pins, and for a final regulation the paper punchings are supposed to be placed underneath the cloth ones. There's a special forked tweezer made to lift all the punchings together. William Braid White pointed out that it's more rational to make large increases in height to groups of keys by shimming under the balance rail.
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