This is a multi-part message in MIME format. ---------------------- multipart/alternative attachment Yes, if you are working with one particular design, then one can come up = with some repeatable, accurate downbearing scheme using dimes, nickels = and whatever else. In practice, as long as the backscale of a piano is = close to "normal" this method probably works OK. But as soon as you get = that oddball in with an unusually long backscale (or short) one could = really start changing things without realizing it. Proper downbearing is very dependant on soundboard design. Some boards = need very little for optimal performance, while some are best set up = with quite a bit more downbearing. Terry Farrell ----- Original Message -----=20 From: Crashvalve@aol.com=20 To: pianotech@ptg.org=20 Sent: Monday, October 06, 2003 11:25 PM Subject: Re: Good at Machining WAS: Reading a Board geometry In a message dated 10/6/03 8:47:52 AM, mfarrel2@tampabay.rr.com = writes: 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. =20 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. =20 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! =20 Terry Farrell I really like that term backscale. If I remember S&S threads a fiber = line on the plate, shims it up with various thickness metal slips, then = sawcuts the cap to clear this line. This means the bridge cap plane is = so many thou above the string plane. This assumes bridge cap is parallel = to board and board is some kind of smooth curve and not dimpled down. If = you wanted to measure actual angles for the angular relationship, you = could but it ain't easy, and I also don't know factors are involved in = setting good down bearings, but I'd like to know ! ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/f9/af/df/b9/attachment.htm ---------------------- multipart/alternative attachment--
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