Oops! Thinking about what I just wrote while tuning a couple uprights today, I saw that my mental image was wrong. Wipp/action rail is behind the bracket, hence shimming it will move the wipp centers back, the opposite direction you want to move. So please omit the shim part of what I wrote. Moving the lower bracket supports, though (which I have done on a couple occasions) can help in the way described. And can definitely (potentially) help an action model that won't regulate right, especially as you can also fairly easily move other things like the whole keyframe. Regards, Fred Sturm University of New Mexico On 10/18/07 7:43 AM, "Fred S Sturm" <fssturm at unm.edu> wrote: > Hi Jim, > Moving (bending) the dowel capstans back mostly affected > the wipp ratio (the key ratio to a much lesser extent), by > moving the contact closer to the wipp center. The same > effect would come from either shimming the wipp rail > forward or moving the action bracket supports forward. > Either of those actions also would change the angle of the > action relative to the strings (or I guess I should say > relative to vertical) so that the shape/angle of the butt > leather at check would be more upright and the jack could > clear more easily (not sure if that wording is clear). > > On the couple early Nordiska uprights I have seen, they > looked like they were, shall we say, not put together > carefully, so even assuming action geometry was a > reasonable design (probably fairly safe assumption), > exactly how they placed the keybed, the keyframe, and the > bottom action bracket supports could easily vary enough to > cause problems. I have found this to be the case with > action models, including those created for the PTG upright > regulation test. A shift of the placement of the keys and > the bottom of the brackets, even a small one, can have a > big effect. > Regards, > Fred Sturm > University of New Mexico > On Tue, 16 Oct 2007 18:31:20 -0600 > Jim Busby <jim_busby at byu.edu> wrote: >> List, >> >> >> >> >> >> Feedback on the short term solution; >> >> >> >> On the Nordiska in question I found that bending the >> (wire) capstans >> backward so they hit further back on the wippen cushion >> indeed solved >> MOST of the problem with bobbling hammers. On hammers >> that continued >> multiple hitting; weakening the damper spring also >> helped with that >> problem. >> >> >> >> IOW, since most of the bobbling came from the butt >> hitting on top of the >> jack moving the capstan increased the distance the >> wippen traveled and >> this extra movement allowed the jack to get out from >> under the butt. >> However, on soft blows the but/jack wasn't the issue. >> The springs were. >> So, it now works to the lady's satisfaction, but not to >> mine! Why? It's >> still .450 dip, about 75 DW and blow is about 41mm. But >> hey, I'm keeping >> my mouth shut... >> >> >> >> Since we're talking a poor execution of design I guess >> the "design flaw" >> and possible correct "fix" should be; >> >> >> >> 1. Move capstans back >> 2. Move wippen cushion to the right spot >> 3. Remove lead (4 leads on the back of each key) to >> obtain a better >> DW >> 4. ???? (Change action post location?) >> >> >> >> Does this seem like a proper correction in design? Not >> that I'll mess >> with it this time, but it's good to know IMO. >> >> >> >> All these years I've been tweaking grands and have never >> really >> considered uprights. I've never been to or seen a class >> on them except >> Jack Wyatt's "Turbo charging the Upright" class. >> >> >> >> Thanks to all who contributed! >> >> >> >> Jim Busby BYU >> >> >> > >
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