I would very much like a set of hammer leathering cauls. On most square grands, in order to get the same tone that the earlier pianos had, you will find the factory covered the modern style felt hammers with leather from the center on up through the treble. The earliest pianos had leather covered hammers. I have restored several sets of all leather hammers. (You cannot use the old leather it is simply turning into powder. The tone turns out very nice in a historic kind of way. One type of hammer starts out with a 1/4"x 1/4" square of heavy solid leather glued to the end of the center molding and then that square is shaped into a half circle. Then with one layer of softer suede leather at a time the hammer is built up gluing and drying each one. Hot glue, of course. Almost every layer is chamfered at the ends and some layers do not go all the way around. I use the original hammers as patterns counting layers and notating full or partial layer. There is no glue in the 11 o'clock to 1 o'clock area of any layer as a rule. There are some layers that only have non glued leather layered between glued layers at the crown. You end up with a hammer which is very much shaped like a modern felt hammer in most cases and matches the piano's original hammers. Also if you glued correctly and stretched the leather enough you have a leather hammer that will bounce just like a new felt hammer will if you drop it. You want the bounce to rebound from the string in a key stroke. The one important thing is to keep sharpening your leather knife as leather dulls the best blade very quickly. There is much trimming and skiving to do in a project like this one. Some smaller and earlier pianos turned the hammers 90 degrees so there is not room for a hammer larger than a dime or they will rub each other. These round hammers are much quicker and easier to make. You cannot use buckskin any more unless you burn a sliver of it to make sure it is chrome tanned. Vegetable or Alum-tanned leather will only last about 6 years and you have wasted all that work to repeat it every 6 years. (If you do not know about leather tanning read the leather page on my technical tips page at the website below) If anyone has equipment for leathering such hammers as used in a factory, I would like to have it or to copy it. I would never consider synthetic leather for anything unless I only expected it to hold up for a year or two. I have tested every synthetic material made for pianos, player pianos, pipe organs and reed organs in the last 30+ years and I have learned that only original materials will take the abuse. Chrome tanning is essential in leather now because of our pollution. If you player buffs are using the old tan pouch leather you will be in for a shock when your restoration will not last for over 12 years. Chrome tanned leather lasts 50+ years that we know of. Good enough for me. D.L. Bullock St. Louis www.thepianoworld.com -----Original Message----- From: Isaac OLEG [mailto:oleg-i@noos.fr] Sent: Tuesday, March 02, 2004 12:24 PM To: Pianotech Subject: RE: buckskin/leather hammer covers Hi agreed on the 8:00 thing, as I've see one mounted like that , the result was decent for a no budget I work may say. The bucksking may be can be artifical leather , more resilient and even. Hot glue is also my choice, as it eventually add some tension to the hammer. I still have to get a few pics of the wooden individual cauls that can be used to press new felt(or leather, why not)and was originally used on Erard's hammers. I 'll try to make a sketch with real dimensions as well. I also have seen interesting gluing pliers tha hold very tight the underfelt if necessary. More difficult to realise. Best Regards.
This PTG archive page provided courtesy of Moy Piano Service, LLC