Hello Jon. JPG me, please. Exactly what natural curve are you trying to remove? Terry Farrell ----- Original Message ----- From: "Jon Page" <jonpage@attbi.com> To: "Pianotech" <pianotech@ptg.org> Sent: Wednesday, December 18, 2002 7:18 AM Subject: Re: Bridgetop Extravaganza Revisited > I wouldn't trust a shallow fill of epoxy to resurface the cap, recap. > > As far as pounding the string, I agree that it is over-rated and have > tapped the bridge pins as Roger Jolly suggested to relieve false beats. > I also devised a tool for removing the natural curve from the wire at the pins > to improve the termination. I posted to the list a few years ago about it, > I have a jpg file if any one is interested in viewing it. > > Regards, > > Jon Page > > At 02:13 AM 12/18/2002 -0800, you wrote: > > Hi All, > >Just joined, first post to this or any other group. Serendipitous > >timing, just read all the recent bridgetop/ bridgepin posts. Have a 1985 > >Stwy D in the shop for action overhaul and restring. I thought I was > >noticeing something funny about the bridges but was in denial until I > >started taking all the teardown notes. The plain wire strings have been > >pounded (seated) into the bridge so that at the edges there is more wire > >diameter below the bridge top than above it. When viewed from the side > >the wire makes a pronounced curve up onto the bridge and down again out > >the rear making accurate component readings impossible to do from on top > >of the wire. It was showing negative front bearing until I realized what > >was happening and started using the actual bridgetop as > >reference. Situation is most severe at capo sections and diminishes down > >to what looks like normal grooves to me under the bass > >strings. Deflection in strung piano is .5 deg at bottom of low > >capo, 1-1.5 deg rest of capo sweeping up to 2.5 deg at note 88. There is > >.250" crown at low capo. (measured from top of board) > > Is it possible this condition is due to the quality of the capping > > material? I usually work on much older instruments. I have never seen > > string cuts like this. Also the various pressures have caused dead wood > > to swell up and check here and there around the terminations. Again I'm > > not used to seeing this. Inspection of the pins under magnification > > shows the string resided in two distinct locations. My theory: Pre- > > and Post Pounding. There are also a lot of unexplainable nicks on the > > side of the pins. The pins pull out easily. No cracks to speak > > of. This is an institutional piano which has probably been in Southern > > California its whole life. > > What I'm thinking about doing is similar to what Dale Erwin just > > posted. I've never done the epoxy bridge thing but I'm familiar with the > > nasty stuff. I'm imagining thickening it enough with colloidal silica so > > it won't run down the notches or too much into the holes and applying it > > with a small spatula. I want to fill those deep grooves (at least on the > > speaking side) and then sand the top flat. If I put the stuff on in the > > morning can I pare/renotch and redrill at the end of the day before it > > gets too hard and while I can still find the original holes? > > Looking forward to peoples responses. > > > > I want to stop using the misnomer "string seating" in favor of wire > > straightening (or something similar) which is what I do at a low lateral > > angle (around the bridges anyway). I have never been convinced of the > > need of downward tapping pressure at the bridges. For some reason this > > is one of the first things new technicians are taught and the thought of > > them going around with little hammers and pounding on pianos scares > > me. We straighten wire for control of damper and hammer contact and for > > quick stabilization of new strings. Perhaps having the wire come > > straight out of the bridge helps the string to vibrate in a more > > perpendicular plane even. I don't really know. After you take a few > > pianos apart you find that even in a negative bearing situation the > > angled pins hold the string tight to the bridge. If there is so much > > negative bearing that they don't then no amount of pounding will hold > > them there. But I guess that is another thread. Right now I need help > > getting out of this mess. I have finally accepted I have to pull the > > plate. So much for the quick restring of a fairly new instrument. > > > >Thanks, Steve Bellieu >
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