Tom Driscoll wrote: > List, > > I performed some regulation on an older Baldwin L today. > This action was rebuilt with all new action parts two years ago by > another tech. and needed routine regulation to put things back in order. > > The problem is with the checking. On a light blow the > hammers are bouncing off the top of the backchecks. The rep .lever > springs are adjusted correctly, key dip, blow, and after touch are all > fine. Hammer tails are well prepped also. Changing the backcheck angle > helped somewhat, but the symptom persists. The backchecks are 1 ¼ ? long > and I?m thinking that a longer backcheck is necessary. > > I see in the pianotech catalog an ?old? Steinway backcheck > listed. > > Advice appreciated. > Tom, The symptoms you describe may be caused by checking too far from the strings. They need to check no further than 5/8" from the string plane. You seem to think that increasing the contact area between the the tail and the back check will improve the situation. I find that you don't need more than about 5/16" contact for good checking assuming things are setup right. The larger checks found on the old S&S will not help. If you have close enough checking and still have problems you may need to improve the friction on the contacting surfaces. Use medium grit sand paper on a paddle and work the buckskin from the top down reestablishing the grain of the leather. If there are indentation in the buckskin try to work these out or replace the leather. Rough the tails with coarse sand paper or a file card. This works well on walnut and mahogany hammer molding but if you have ones that are maple or birch you will need to use a checking file. John Hartman RPT John Hartman Pianos [link redacted at request of site owner - Jul 25, 2015] Rebuilding Steinway and Mason & Hamlin Grand Pianos Since 1979 Piano Technicians Journal Journal Illustrator/Contributing Editor [link redacted at request of site owner - Jul 25, 2015]
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