This is a multi-part message in MIME format. ---------------------- multipart/alternative attachment You want to measure the angular relationship of the string in three = areas: along the speaking length; along the bridge top; and along the = backscale just aft of the rear bridge pin. Those measurements will give = you all the data you need to characterize downbearing. Be aware that all these references to setting bearing to "the thickness = of a nickel" or whatever level above some reference point may be fine = and dandy, but are completely dependent on the length of the backscale. = As the backscale length between two systems where this type of = measurement is being used varies, inaccuracies in the reference = thickness will be introduced. How much downbearing is desirable will depend on the soundboard assembly = design, where you are in the scale, and a host of other factors I know = very little about! Terry Farrell ----- Original Message -----=20 From: Crashvalve@aol.com=20 To: pianotech@ptg.org=20 Sent: Monday, October 06, 2003 7:38 AM Subject: Re: Good at Machining WAS: Reading a Board geometry In a message dated 10/6/03 12:54:05 AM, yardbird@vermontel.net writes: I'm assuming you've got some sort of milling machine, not = necessarily a Bridgeport. I bet you could do a good job of making a component downbearing gauge, the one with the adjustable inclination bubble mount. Someone send this guy a .jpg of one (not necessarily identifying its maker). Bill Ballard RPT NH Chapter, P.T.G. Living near Detroit I have acquired lots of machinery from old tool = and die shops. To do credible work you need both a mill and a lathe and = a lot of support tooling. Can be a time waster in that one of three = experiments is good to go. Re the downbearing gauge I bought one from = one of the suppliers years ago and returned it because of the low = precision bubble vial. Your best bet would be a simple jig with a place = to temp. mount a machinist's level. A good one is accurate to .005 per = foot and a REALLY good one goes .0005 per foot. Question is (and this = goes back to the vector discussion in recent threads) what do you want = to measure, which two surfaces to you want to relate to each other ? = Even S&S once specified thickness of a NEW coin for down bearing = gauging, or was that just romantical hype ? ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/ef/c4/6b/0f/attachment.htm ---------------------- multipart/alternative attachment--
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