I don't think I've seen a version of balance hole replacement jig like this so I figured I'd post this. The concept and building of the jig is dead simple, cheap and the accuracy of the holes was dead nuts..no front to back or side to side wandering of the keys whatsoever. It consists of 2 small jigs made of aluminum jig plate scrap or just plain aluminum scrap . 1 piece is 1/2" x 1/2" thick and one is 1"x 1/4" thick (actually this piece is a home depot special) piece. -Drill 3 holes in each piece with the hole centers forming a straight line. Spacing of the holes is arbitrary. HOWEVER, the hole centers on both pieces must match identically. -The spacing of the centers needs to be absolutely identical on both pieces. -Place the middle balance pin hole (for either a balance pinstub, or balance hole drilling drill bushing) so it is not centered in between the two index pin holes. Actually make it well off from centered between the index pin holes, as this avoids the pitfall of placing the jig on the key backwards...it makes it impossible to screw up...only fits one way for Murphy insurance... jig piece#1 1"x 1/4" locates index holes referenced off the original balance hole. The jig's center pin is a .146 balance pin stub. the two index drilling holes have a #44 (.086") drill bushing pressed in that will allow # bridge pins to be used as index pins. Locate the jig on the old balance hole, clamp and drill both index holes by hand, with a #44 bit. I stick a #44 bit in the first index hole after it has been drilled to make sure things don't move in relation to the balance hole for the second index hole. Dado out old hole to 3mm deep in the old shoe. Glue in 3mm basswood veneer. jig piece #2 1/2" x 1/2" jig plate( or whatever), uses the drilled index pin locations to locate the new balance hole. The center hole is a #27 drill bushing (.144"). Tap the bridge pins into the index hole, and you can't screw it up, assuming your jig's three centers are dead on. I probably could have gone with a #26(.146) drill bushing, but I was being conservative on this one and final reaming by hand. Worked a treat...no boo boos by design. Jim Ialeggio -- Jim Ialeggio jim at grandpianosolutions.com (978) 425-9026 Shirley, MA -------------- next part -------------- A non-text attachment was scrubbed... Name: balance-hole-jig.jpg Type: image/jpeg Size: 21841 bytes Desc: not available URL: <https://www.moypiano.com/ptg/pianotech.php/attachments/20120725/4292031e/attachment-0004.jpg> -------------- next part -------------- A non-text attachment was scrubbed... Name: old-hole-and-new-reference-.jpg Type: image/jpeg Size: 23004 bytes Desc: not available URL: <https://www.moypiano.com/ptg/pianotech.php/attachments/20120725/4292031e/attachment-0005.jpg> -------------- next part -------------- A non-text attachment was scrubbed... Name: balance-hole-step2.jpg Type: image/jpeg Size: 26238 bytes Desc: not available URL: <https://www.moypiano.com/ptg/pianotech.php/attachments/20120725/4292031e/attachment-0006.jpg> -------------- next part -------------- A non-text attachment was scrubbed... Name: drilling-new-balance-hole.jpg Type: image/jpeg Size: 31708 bytes Desc: not available URL: <https://www.moypiano.com/ptg/pianotech.php/attachments/20120725/4292031e/attachment-0007.jpg>
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