Terry wrote: <But my question remains unanswered: from a structural standpoint, what would be the problem with filling a wide gap the entire length of the flange to pinblock joint? I don't think there would be a problem. Terry, to address, but perhaps not definitively answer your specific question. My experience of epoxy, both in my previous field of architectural historic conservation, and in the piano realm is that, the substance has some unique and valuable qualities, but it is not the cure all panacea many assume it out to be. It, like any substance, natural or man-made, has limitations. In the 80's when the historic conservation crowd took on epoxy with gusto, is was used sometimes to create large structural gaps, in structural and decorative timbers. Five years down the road, the large gaps exhibited a huge failure rate. The protocols were adjusted to use it as an adhesive between reasonably fit "Dutchmen" with no more than 1/4" glue lines, and preferably less. The problem was that the expansion rates of the epoxy and its surrounding materials were incompatible. In a large gap the relative inflexibility of epoxy was simply too hard and brittle to withstand the push and pull of wood. Also, epoxy continues to harden as it ages, becoming more brittle than even a 30 day complete cure would suggest. It continues to crosslink. How long, I don't know, but even the most flexible epoxies, turned into brittle masses over a period of years. So assuming your flange/block joint depended entirely on the epoxy for its fit, would this aging brittle material be able to take the load you are wondering about...maybe and maybe not??? It seems, from what I've seen, that the situation where epoxy performs most reliably is when it is used as a component of a composite. The "pretty good wood to flange fit" with epoxy consolidating the wood bearing surface a little bit, and the epoxy effectively spreading the load to the entire wooden bearing face, makes long term sense to me. It uses the substance as a component of a composite. That's why I use it in this fashion. I have had, even very recently, epoxy failures. These failures which never made it into a piano, but only as test joints. These failures, and all my previous experience with the stuff leads me to use it conservatively. Jim Ialeggio -- Jim Ialeggio jim at grandpianosolutions.com 978 425-9026 Shirley Center, MA
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