Phil and all, >One more question before this thread dies. What size slot do people >cut? Or in other words, how much clearance do you allow for the >knuckle core? > >Phil Ford We use a 2 mm slotting cutter to provide a slight interference fit with the knuckle tongue. The original slot is filled prior to cutting the new one. With only 20 + mm distance between hammer center and the jack/knuckle contact, it doesn't take much of an error to make a significant difference in the note-to-note hammer/key ratio. We use a small milling machine for this work. The head can be rotated to any angle, so we set the chuck axis parallel to the table so that the jig can be mounted horizontally, and packed up to enable appropriate XYZ adjustment between the cutter and the work-piece. When doing this work, its worth checking that your machine used doesn't have axial float. A 2 mm slotting cutter fitted to a machine with 0.25 mm axial float results in slots which vary from 2 to 2.25 mm. Our mill has a cap screw style lock on the rack and pinion quill, so its a simple matter to lock it. I second one of your earlier post Phil. There seem to be regular occurrences where technicians rebuild grand actions with off the shelf parts which are inappropriate to the job at hand. Often one part of a poor-action-geometry fix will involve relocating the knuckle slot to 17 mm from 15.5. We've reset quite a few of these where the parts were practically new. Ron O. -- OVERS PIANOS - SYDNEY Grand Piano Manufacturers _______________________ Web http://overspianos.com.au mailto:info@overspianos.com.au _______________________
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