Don 't know about the bowing as not having the before measurements and not having glued up these laminated blocks myself I can't say what happened there. Blocks do arrive with some bowing sometimes and a small bit of bowing is not that big a deal as once you tighten the pin block screws it will pull the block snug to the plate. I try to keep that to a minimum, of course, and 10 mm seems like a fair amount but others may comment on this. I've never really tested the limits of what can be done there. On shimming the board up at the ends to achieve the required plate height, there's nothing wrong with doing that, I do it all the time. It's a hell of lot easier than planning down the entire block and certainly more acceptable than taking material off the inner rim and lowering the bottom of the block below the level of the stretcher. David Love www.davidlovepianos.com From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf Of Duane McGuire Sent: Sunday, April 04, 2010 10:32 AM To: pianotech at ptg.org Subject: [pianotech] Pinblock expensive experiment I think that my first grand pinblock replacement has become an expensive experiment. I wanted to do the multi-lam capped with delignit block that Ron Nossaman described at Grand Rapids and was documented in the journal. I resawed the delignit and planed a 9mm cap for the block. Before gluing up I noted that the multi-lam (Schaff) was not exactly flat, but I did not measure its degree of bow (I believe this is the root an expensive mistake). I selected a clamping caul with a compensating bow, and glued the assembly up, thinking that it would tend to flatten out. After unclamping and planing the multilam to final thickness per the original block, I find that the bow in the board is just plain awful. Total deflection measured at the midpoint of the board is 10 mm! I'm thinking I have some more firewood for next winter. By the way, the original block measures 39.6 mm, and from my look at the suppliers, Bulduc's 1-5/8 is the only material that will match that thickness. At the same time, I do suppose a person could place blocking at the ends, and use a somewhat thinner board. From my starting, I didn't find that idea appealing, but I'm looking at this from every direction now. Right now my thought is that tomorrow I order a Bolduc pinblock and get on with it. But rather than just reacting to my own self-pity, I'd appreciate your input, before my wallet gets even thinner. In the category of self recrimination, I expect that I should have measured the bow in that multi-lam and shipped it back when I found the degree of deflection that was present. Thoughts? -- Duane McGuire 801-830-5858 http://blog.duanemcguire.com -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/pianotech.php/attachments/20100404/6da3fbb4/attachment.htm>
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