---------------------- multipart/alternative attachment Hi Clyde The real pioneers of this technology if I'm correct rightly goes to folks such as Del Fandrich,Ron Overs in Australia & Ron Nossaman from the great state of Kansas. What these guys have learned they've freely shared on this list for many years& I'm simply along for an interesting journey in sound production thanks to them. The cut off bars & fish are essentially mechanical ways to increase soundboard crown reliability , longevity & enhancing mechanical impedance. By Adding a bass cutoff bar the bridge is sitting more in the center of & on the highest part of the rib/crowmn.. Shortening the rib obviously makes it stiffer. Crowning the ribs & making them taller & less wide also aids this. I rebuilt A 1905 Bluethner 6 ft grand that had a beautiful sweeping cutoff bar but the ribs had no height/depth consequently no crown. So cutoffs are not new but they are being incorporated with other design features these days such as taller & narrower ribs to support crown instead of to much destructive Panel compression. I really feel like the ones who should be explaining this should be the brothers mentioned above. Also the archives are full of this. Check out WWW. Ron Overs Or Del Fandrich Northwest piano Builders. Also Terry Farrel is making component part for the trade such as custom one off cut off bars. Some of this work is math, science & educating guessing & plain common sense. At any rate I'm glad it's got your interest. Regards Dale Dale, This work you are doing to enhance the performance of re-build projects is very amazing. Adding cutoff bars and "fish" (which I suppose is the equivalent to a cutoff bar for the high treble) is very interesting. Would you share how to calculate the positioning of the cutoff bar and fish. I suppose (and perhaps wrongly so) that the cutoff bars positioning is a function of the soundboards area and rib lengths? What is the correct way to determine the cutoffs positioning? and how do you arrive at the dimensions and positioning for the fish? Thanks in advance for your help in this matter. I've just been going through the pictures you posted and find this fascinating! Clyde Allen PTG Assoc. Silver Spring, MD Erwinspiano@aol.com wrote: Too All The pictures show a added cut off bar I posted about last week which was recycled from the baldwin upright. I decided to add the fish in the treble after Terry posted his pictures & alos because of input from many other rebuilders on list that have discussed more modern approaches to developing sustain & power in conjunction with sound board crown longevity. As posted previously the ribs on this piano are extremely long & would have provided inadequate crown support. Also the ribs & soundboard area in the top treble were extremely generous to the point of sacrificing stiffness required for adequate impedance. I'm changing all the tri-chords top bichords & probaly a bass bridge change too. The jury's still out tonally. I'll! report back when its strung. The action is already to go so in march I'll tell "The rest of the story" We pressed the board today, the block is made as seen in picture. Dale Erwin [Photos at:] http://tinyurl.com/3jmod http://tinyurl.com/4y95u http://tinyurl.com/48ztm http://tinyurl.com/5fmsb http://tinyurl.com/6yron [Direct ptg.org URLs:] https://www.moypiano.com/ptg/files/attachments/f5/86/c0/a5/DSCN4569.JPG https://www.moypiano.com/ptg/files/attachments/5e/16/2e/fb/DSCN4570.JPG https://www.moypiano.com/ptg/files/attachments/6f/92/1c/64/DSCN4571.JPG https://www.moypiano.com/ptg/files/attachments/c2/6c/44/4a/DSCN4572.JPG https://www.moypiano.com/ptg/files/attachments/45/2c/31/4a/DSCN4573.JPG Erwins Pianos Restorations 4721 Parker Rd. Modesto, Ca 95357 209-577-8397 Rebuilt Steinway , Mason &Hamlin Sales www.Erwinspiano.com _______________________________________________ ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/3a/58/a0/8b/attachment.htm ---------------------- multipart/alternative attachment--
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