Yesterday I did a hammer re-facing on a client's 1929 Challen upright. Hammer re-facing is a job I enjoy doing. I take care to keep a proper shape, and it never seems all that difficult to me, yet I have seen some horrible jobs. Recently I saw a piano where the hammers were all lop-sided because someone had done a very crude re-facing by filing (with I know not what implement, the hammer felt looked all roughed-up) from the top side only, towards and over the striking face. The hammer bottoms had not been touched. I was musing about the conventional wisdom which says that after re-facing, the blow distance should be adjusted by packing felt behind the hammer rest rail, and the action re-regulated. In practice I have seldom done this after re-facing. There is the practical consideration of what the customer would be willing to pay, balanced with the very substantial improvement to an old piano that can be made just by re-facing. What I was thinking, is this: If you re-face carefully, you don't increase the blow distance beyond what it already is, because you only file the hammers to the level of the bottom of the exisiting grooves. The existing blow distance is from the bottom of the grooves to the strings. If the action is reasonably good at that distance, and it's not a top-grade piano or a customer with lots of money, is it necessary to mess with packing the rest rail etc? A fairly quick hammer re-facing, along with tightening all flange screws and taking up lost morion, can make a huge difference to the sound and feel of a semi-decent old upright, at reasonable cost. And in any case, adjusting the blow distance to what it originally might have been, does not restore the piano to what it was, as it now has smaller hammers and an altered action geometry. Best regards, David.
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