Thanks Dale, Let me see if I can get a bit more from you. What if you went one step further and began with only the key frame, glides turned up, no key blocks, other than to determine position? What do you want to see? No knocking from back rail, no contact between frame and bed until front rail. Solid contact there except for ends. If an accurately fitting bare frame developed some anomalies with the introduction of the action frame, it seems you'd want to know that. Once you're satisfied with the bedding of the back rail, there is the issue of the dags. Or not. By Ron's measure, the only thing you need to ascertain is that there is no binding or chance of inadvertent contact. For the stressed-frame approach, it would seem that you strive for a perfect fit. You said - > As far as pre mature wear due to increased stress I think more of > that would come more by all the leads found in the keys of many > famous pianos. Stwy,M&H, Baldwin etc. An abundance of lead would bear on the front and back rail, add mass to the frame, forcing a heavier shift spring loading. I was, I think, misguided in concern for wear at the keyblocks and guide pins. They should be unaffected, but if the glides are adjusted properly, there would be the same amount of loading on them, whatever the amount of keyleading. The only difference would be that (again, using the Steinway method), when lifting the frame and testing for knock, the resistance would be from the key weight, whereas, with a lightly leaded action you would be springing the frame a bit more. It would seem then, that there is a somewhat greater chance of lifting the back rail when bedding the lightly weighted key frame than one with much lead. Trying to tension-stress (deformation) in a heavily leaded key frame would likely create a greater friction problem than the same procedure on a lightly leaded one. So what am I not getting? David Skolnik Hastings on Hudson, NY At 10:31 AM 7/8/2008, you wrote: > Hi David > good post. > Now let's exercise a little techno prudence with this idea > before some one raises the balance rail higher than a car changing a flat. > I have safely raised key heights 20 to 30 thou without negative > affect. For me that's the limit. Ok? Enough to effect a slight but > significant change in key level ,dip & aftertouch when needed. This > maneuver may not always be appropriate & the real fix is to start > over as described below. > As far as pre mature wear due to increased stress I think more > of that would come more by all the leads found in the keys of many > famous pianos. Stwy,M&H, Baldwin etc. > I like to set the keybed/keyframe contact with keys off & action > screwed to frame (as per Yamaha) so I can really understand the > unloaded strength of the keyframe I am working with. This is a > good starting place. It is also to experiment with turning bolts > up & down to judge the effect of the back rail ie. is it lifting > tapping etc. All is visually accessabile > Well I do not know what the deficiencies of Setting the glide > bolts on Steinway pianos are but I have not found one case on a new > Steinway where the glide bolts were any where's near the keybed. I > can't explain it. It must be the dealers responsibility..sic...GRRR...Loudly > Dale > > >Requesting a little perspective: >What are the deficiencies of the Steinway method of setting glide bolts? > >Establishing the practical parameters of frame bedding, once I've >established defined contact to effectively preclude any knocking, >how much additional stress could I introduce into the system before >beginning to observe negative effects? : > - increased resistance of una corda shift > - premature squeaking at glide contact > - increase in friction and wear of keyblock plates and > frame guide pins > - change in keydip, aftertouch, > - create knocking at front rail or back rail > >Regarding dags: > - are dags essential to proper function of the action? > i.e.: would back rail [necessarily] slap in their absence? > - how much force (at glide bolt) would be required to > compromise otherwise firm contact of back rail, to the point > where firm capture by dag is required? > - if the dags are used to compensate for insufficient care > in back rail bedding, then wear and seasonal variation > could allow for the slap of Jude's observation. (another > cause could be flat, un-arched front to back profile). > >I'm not sure that Andre's tuning fork analogy is operational >here. I would need to hear a more thorough explanation. > >I do love finding new uses for my caliper. Especially fond of them >in key leveling. > >David Skolnik >Hastings on Hudson, NY
This PTG archive page provided courtesy of Moy Piano Service, LLC