---------------------- multipart/alternative attachment Glenn writes If you have a full board ready to install and you decide to thin it, how do you measure you planning progress? You're asking the hard technical questions. My engineer friend say that when his friends get picky with details the comment is "hey your not building a piano ya know" I take that as a compliment. In this case we are but fortunately board thinning isn't a mystery. It however helps to have an organized approach to thinning. If you ask 5 belly guys how they do it you'll get five different answers. The amount of thinning depends on what your goals is & what you think is benifiacial to freeing up the edges of a board. The thinning in most regimines includes thinning along the spine(straight side), on around the tail around the curve and stopping short of the top treble area which needs no or little thinning. Some also thin along the belly rail up to the offset of the board ,which is sometimes desireable depending on the overal thickness of the board to start. This is not an area that I find much thinning on in old boards Thinning is mostly restricted to the areas directly over the thin part o or cutouts on the rib generally comprising 4 to 6"or more out into the panel. The area that benifits the most from thinning in my opinion is the area beginning where the tail curves around and behind the bass bridge. This area needs to move. If I'm planning a board thats overall thickness is say .350 In the middle It is common to have starting thinness at the edge of between . 250 or so. I personally don't like to get any thinner than this and usually don't. More like .275 ish. I use a a plunge router that swings a 1 1/2"bit. Kinda scary! It sits in a big flat 3/8" plexiglass jig with a beveled piece of spruce that approximates the beveled edge of a board. The wedge sits between the router & the plexi which angles the router & bit. It's possible to increase or decrease the angle by shimming between the wedge and the router. The flat Plexiglas panel with router on top (Approx. 8 by 12) rides on top of the panel. There's an adjustable fence the sits down below the panel the follows the edge of the board. With each pass around the board the fence is adjusted outward to allow the router bit to move farther in on the panel. The cut height is adjusted by turning the knob on the router raising the bit until it cuts at a level above the last cut. The whole device is run around the board usually bout 4 to 5 times, each time at a different level. I then do some final hand planning to smooth things up & finish off with a belt sander & then an orbital of various grits. I'll often hand plane a bit more behind the bass section. I'll try to JPG a picture of the thing. Also it's easy to make a pair of wooden armed calipers that can measure in on the board. Dale Sorry about the first incomplete transmission. Operator error ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/45/52/f7/ed/attachment.htm ---------------------- multipart/alternative attachment--
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