Bob Hull wrote: >Hello Richard, > > >Thanks for a reply all the way from Norway! > >This piano is a Hamburg Steinway D. I had read (in an >article by David Stanwood) that a 5.5 ratio was best >or perhaps normal for a Hamburg D. But can that ratio >vary from piano to piano as this one may be >indicating? I agree with you that the numbers I gave >did lean more toward a 5.7 and the numbers had been >rounded down to the nearest 1 decimal pt. > > Well, David has no doubt far more data on the matter then I do. But the ones I see look more like 5.6-5.7. You measurements lean in that direction too as I read them. Remember tho that measuring the BWR (SWR) is far from an exacting science. You are highly dependant on getting the same A Balance Weight reading of 38 vs one of 36 is going to have a pretty significant affect on your resulting ratio figure. So that might (probably) figures into this as well. Otherwise, David has a preference for heavier hammers to begin with, especially for big pianos. So he's no doubt slightly <<biased>> towards a lower ratio from the get go. The thing is tho... you have to think about which way you want to err if you do err at all. If you figure you have a 5.5 ratio and put on a # 10 SW curve and it turns out you have a 5.7 ratio...then either your FW's will need exceed the maximums or you will have to accept a heavier BW. On the other hand... if you figure 5.7 ratio and put on a # 9 SW curve and it turns out you have a 5.5 ratio.. then you can get well under the Front weight maximums. Only makes sense really... heavier hammers mean more frontweight or more balance weight... yes ?? :) So I like to play a bit safe when it comes to measuring the ratio Davids way. >If I understand the procedure you're suggesting then I >will proceed as follows: >1. Adjust the strike weight for each hammer to the >weights listed in the number 9 curve. >2. Adjust the front weights to not exceed the >maximums. (Or should they even be given a margin >slightly below the maximum?) Should this improve the >BW and get it to the desired 38? > > Put them exactly on the FW maximums provided in the kit.. If you run the equation of balance for the appropriate parameters the resulting FW's conform to those maximums. >3. Calculate the resultant Strike weight ratios. >4. Adjust ratios as necessary by change/shimming of >fulcrum point near balance rail. Should every note >have a 5.7 ratio or can there be slight variance on >some notes. When you talked about knuckle angle are >you talking about regulation of the jack to knuckle >position? If so, are you saying that this can affect >the swr? > > Id first look at the knuckles and regulation real closely to see if I can get the individual resultant key ratios close enough in line. Changing the key ratio by shimming as I mentioned is usually something I do only if I have no other recourse. On a D, you might look at individual action spread... A mm here or there can mean a lot. Also look at your capstan line... an off line capstan can also cause ratio discrepancies. >5. Deal with friction problems. > >Basically your instructions seemed clear, just a few >questions remain as listed above. > > Yep.. thats about my routine. Once you have SW's and FW's as knowns and are dead on accurate... the rest is diagnostics. First hunt down and identify BW problems, then take care of friction. >Have a good day! > >Bob Hull > > > > Cheers RicB
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