I use titebond for broken key repair. The pieces, indeed, are perfectly mated...you just open up enough to get the glue and move it back and forth to get it everywhere and then clamp. David Ilvedson, RPT Pacifica, CA 94044 ----- Original message ---------------------------------------- From: "Terry Farrell" <mfarrel2 at tampabay.rr.com> To: pmc033 at earthlink.net; pianotech at ptg.org Received: 4/29/2010 8:48:19 AM Subject: Re: [pianotech] Glue Strength for Pedal Lyre Repair >I'd guess that Tom's response is 50/50 correct - good chance your glue >job will hold, but I wouldn't bet my kids college fund on it. As Paul >eludes to, a wood glue (i.e. Titebond) joint needs well-prepared >(smooth & properly mating) surfaces for maximum strength - most often >a split piece of wood clamped back together will not provide the ideal >gluing surface (often very difficult to get a perfectly mating >surface). I agree with Paul that this is a situation were epoxy would >be best because of its excellent large gap filling properties. I would >recommend using the West System two-step bonding method for a >situation like this where you want maximum strength. >However, since you have already glued it. I would recommend adding the >dowels perpendicular to the long axis (grain direction) of the top >block - I'd drill them slightly oversize, swab the hole and the dowel >with unthickened epoxy and then add epoxy thickened with high-strength >adhesive filler to the hole and push the dowel in. Use fast curing >hardener and it will be hard as nails overnight. >And then, as Paul pointed out, you have the issue with the supports >(vertical posts between the top block and the pedal box). Either re-do >the original wedges - or, if you didn't get the top block perfectly >back together (the support holes may be larger now), you might want to >just epoxy the posts back in (I hate to do that, but if your top holes >are enlarged, it may be the easiest way out. Or make new supports - or >better yet, make a new top block. >Terry Farrell >On Apr 29, 2010, at 10:01 AM, pmc033 at earthlink.net wrote: >> Hi, Paul: >> Usually, wedges are used in the ends of the lyre supports, where they >> enter the top block and lyre box. In addition to glue, these wedges >> provide a very tight joint. Now that the block has been split, the >> original strength of that joint has been compromised. Even though >> you have >> reglued the block, I'd be a little apprehensive about the strength >> of it. >> Sometimes there is a screw driven into the joint, which on the surface >> appears to add to the strength, but in fact doesn't do much at all. >> Putting >> new wedges into the ends of the supports is absolutely necessary for >> the >> strength of that joint. If you didn't remove the supports before you >> glued the top block together, I'd be concerned about it. I would have >> disassembled the entire joint, reglued (and doweled) the top block >> first. >> Then removed the wedges (assuming that they were there to begin with), >> inserted the supports with glue and driven in new wedges. I would >> use >> epoxy only, no wood glue. Once a wood glue joint has been broken, >> adding >> more wood glue won't hold. It needs fresh wood, and doesn't fill >> gaps well >> enough to provide strength. Will your repair hold for the next >> concert? >> Probably, assuming you have the pedal supports tightened properly. >> The >> pedal box must have absolutely no movement whatsoever when you push >> on it. >> Especially since your current glue joint is unsupported with any >> dowels. >> If the pedal box is secure and doesn't wobble, you probably won't >> have any >> problem. But if it moves slightly, the leverage and stress on the >> joint >> may break it again. >> My take. >> Paul McCloud >> San Diego >> >> >>> [Original Message] >>> From: Paul Milesi, RPT <paul at pmpiano.com> >>> To: PTG Pianotech List <pianotech at ptg.org>; PTG CAUT List <caut at ptg.org >>> > >>> Date: 04/29/2010 5:45:27 AM >>> Subject: [pianotech] Glue Strength for Pedal Lyre Repair >>> >>> Advice sought ASAP. One of my high-profile clients, an embassy >>> here in DC, >>> tried to move a 1917 Steinway B off a 2' stage without professional >>> mover or >>> counsel and broke the lyre off. :( Broke the top block in half >>> the long >>> way, right along where the two rear screws go in. Clean break, but >>> left >>> half the block and plate attached to the piano, and of course the >>> lyre on >>> the floor. >>> >>> Piano is needed for concert Saturday 10 AM! A couple techs here >>> advised >>> gluing original block with Titebond. Thought this might be >>> adequate, as >>> glue joint will be stronger than wood. I confess I have limited >>> woodworking >>> experience, so still find it difficult to put my faith in a glue >>> joint being >>> that strong. :) When I expressed doubt, it was suggested that I >>> might >>> possibly drill from rear of block to install two 1/2" or 3/4" dowels, >>> stopping short of front of block, for reinforcement. >>> >>> This morning I unclamped the lyre block after 24 hours and my glue >>> repair >>> appears solid. Can I put the lyre on for Saturday's concert and >>> trust it >>> not to fall apart? I don't have access to a drill press until >>> early next >>> week. Might I try to drill 1/2" or 3/8" for dowel freehand with >>> hand drill? >>> Or should I leave well enough alone? >>> >>> By the way, I have thought about borrowing a lyre from a school >>> piano and >>> seeing if it fits. Just a fallback position. Might I make it work >>> easily? >>> Not my first choice, but emergency situation with very limited time >>> to work >>> with making me think outside the box a bit. Schedule jammed every >>> day this >>> week with performance work, so somewhat stressed! Didn't need this >>> kind of >>> repair/worry. >>> >>> Thanks for any advice. >>> >>> Paul Milesi, RPT >>> Washington, DC >>> (202) 667-3136 >>> E-mail: paul at pmpiano.com >>> Website: http://www.pmpiano.com >>> >> Dude, >> Two words : Re- lax. With all that surface area that repair >> will be strong. If few dowels inserted will give you peace of >> mind , why not go ahead and free hand drilling is more than adequate. >> We tossed around the concept of lyre as a pivot when setting up a >> grand piano a few weeks ago and to be safe I would not use this >> repaired lyre as such and also forget the replacement lyre idea. If >> this was newer a Yamaha and you had the same model available it >> might work but on an older Steinway there are too many variables . >> Just one more piece of advice---Sit at the back of the auditorium >> and if you hear a big crack and the lyre falls onto the pianists >> shins you can slip out the back unnoticed. >> >> Tom Driscoll
This PTG archive page provided courtesy of Moy Piano Service, LLC