Hi Chuck: Have fun with it, but I am not sure it would save you any time or be any more accurate. I’ve fit many a Steinway block and others over the years. It is almost always my practice to top fit the pinblock to the bottom of the plate as well as face fit it to the flange. Like others on the list, I have seen very warped plates every way from Sunday, but my fitting is more or less the same for all. With a block like yours where you know you will be taking down the ends quite a bit, I would take some thickness measurements on the old block at the ends. Then I would use a belt sander or power hand planer to hog the material down to something above the height of your sample. Don’t be too fussy yet. Having either chalked or graphite the face flange and the bottom of the plate, I would start by smacking the pinblock along its length with a mallet against the bottom of the plate. Then I use a 4” disc sander with 60 grit paper on it to start grinding down the high spots. (Or use the belt sander if you are still hogging a fair amount off. Keep grinding down the high spots that are indicated by the chalk or graphite marks. You will be wacking the pinblock against the face flange and grinding down the high spots. Go back and forth between the face and the top. When the entire length of the top of the pinblock lies flat on the plate without rocking you are there. Same for the face flange. I would urge you to have immediate access to the piano (as in be working with the piano in the same room.). If you are regluing the block to the stretcher and the ends (what we would call a fully fitted block). You are starting with a block that should be too long, too wide, and too deep, and then cutting off the excess where needed to get an exact fit – along with some indexing method that will allow you to do all this and still get the plate back where it was before fore and aft, and side to side, within a tolerance of 1/64” or less. If the fellow who brought you the block to do does not have some kind of protocol for plate location, this is a recipe for disaster. Using the plate bolts as guides will allow a tolerance of about ¼” in any direction, which is the same as no guides at all. It is vitally important for you to have all of his teardown specs related to the plate and pinblock – the two of you need to know that you are on the same page. Good luck, Chuck! Will From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf Of Chuck Behm Sent: Tuesday, September 15, 2009 8:13 PM To: pianotech at ptg.org Subject: [pianotech] Subject: Re: Subject: Re: Curved cast iron plate question Hi Chuck: >Let me add my two cents here. First, I would start with a pinblock that is the thickest you can get, since you are going to be taking quite a bit off. You can always joint it off the bottom if the finished block is still too thick, but you don't want to end up with a block that is way too thin. Plate height references from the original teardown, along with string heights and the shank center pin height are important. Assuming that the original plate height was reasonably correct for the action, you would want to get it back in the ballpark, and that new pinblock is going to control plate height for good or bad. The rebuilder who brought the block should have recorded this information from the piano before teardown. !/4" is a lot, but many of us have seen it before, along with the other weirdball stuff. Will Truitt< Thanks Will, and everyone else for your valuable suggestions. I'd like to explain my plan for fitting a new pinblock to this plate. If anyone has a better way of doing it, I would love to hear about it before I invest the time that the method I've come up is going to take. Without pictures, then, I'll try to explain. (Pictures are my crutch in writing articles. If I can't explain something in words, I just snap a picture.Unfortunately, I haven't done this procedure yet thus no pictures.) First of all, the old pinblock fits pretty good, but it's not perfect. If you put it in place on the plate, and put the palms of your hands on opposite corners from each other and press down alternatively, the block rocks slightly. So, instead of duplicating it, then having to figure out how to eliminate the rocking, I'll make a Plaster of Paris mold of the underside of the webbing, using Saran Wrap to keep the plaster from entering the holes, and a dam on the sides and back (where the stringer would be), so I can end up with a usable thickness. With the Plaster of Paris mold, I'll make the duplicate using a jig I'm building. The jig has a base of 1 and 1/2 inch pinblock material for stability. It's large enough to fit the new pinblock with room to spare all around. In each of the 4 corners and also halfway along the length of the base on either side, 6" X 1" diameter bolts extend upward with the threaded ends pointing up. The Plaster of Paris mold will rest on this base, with the impression side upward and flat side down. Over the base, with holes drilled slightly larger than the bolts, will be a floating piece of pinblock material, which will be suspended over the plaster mold by nuts on the bolts set so that the bottom of this piece will be approximately an inch higher than the top of the surface of the plaster. This floating pinblock will be drilled in a 1" grid, and 3" screws will be driven down every square inch. With the mold secured, each screw (with blunted tips) will be turned down until contact is just made with the plaster. Screws that are in line with pin holes won't be used. With all the available screws turned down to represent the contour of the mold, the mold and the floating pinblock will be removed, and the new pinblock, cut to fit the flange of the plate, will be put into place with the side to be mated to the plate facing up, and aligned according to reference points. Then the floating pinblock will be replaced and lowered down on the bolts, with the nuts adjusted so that the 3" screw which has been turned down the least (indicating the high point) will just barely make contact with the new pinblock. Using a block of wood with oversized holes drilled every inch to fit over the heads of the 3" screws, a mallet will be used to tap the impression of the contour into the new pinblock all the way down until the floating pinblock is resting on the nuts. The new pinblock blank will then be removed from the jig, and planed until all the blunted impressions of the contour screws have been removed. In theory at least, it seems this new surface should mate up with the curved surface of the plate. Final fitting will be involved as the flange edge is ground to fit. If this makes any sense at all, will it work? Or would there be another simpler method for matching the wood to the metal that has been dealt with here in the past that I missed reading about. Thanks again to all for taking time to lend much needed support. I'm a jack of all trades, but also a master of none, I'm afraid. Chuck -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/pianotech.php/attachments/20090916/ad17c253/attachment.htm>
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