Dean: Thanks for the refresher! But this is still a misleading use of language which has led to my personal experience of many young technicians thinking, because of the misdirection in the nomenclature, that brass has natural lubricity. I'm glad you understand the difference, and I'm interested that a "professor in engineering materials" misled you by the improper use of a phrase which has created more ignorance than understanding. We can at least try, as "technicians", not scientists, to get our language right for the sake of clear communication. Paul In a message dated 3/5/2009 10:39:15 A.M. Central Standard Time, deanmay at pianorebuilders.com writes: Self lubricating is how my professor in engineering materials class referred to it. No oil magically appears. In the interest of saving time I’ll just repost our previous lubricatious exchange of a year and a half ago: From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf Of PAULREVENKOJONES Sent: Wednesday, August 08, 2007 5:55 PM To: Pianotech List Subject: Re: Counter-bearing drag It's the mythology to which I referred. Language does strange things as we both know. Since we, as a group, tend to be technicians and not engineers, our language tends to be self-lubricating :-). Paul "If you want to know the truth, stop having opinions" (Chinese fortune cookie) In a message dated 08/08/07 08:55:32 Central Daylight Time, deanmay at pianorebuilders.com writes: VERB:Inflected forms: lu·bri·cat·ed, lu·bri·cat·ing, lu·bri·cates TRANSITIVE VERB:1. To apply a lubricant to. 2. To make slippery or smooth. It is of course the second definition to which I was referring. On a molecular level the interaction of some metals against each other produces an above normal amount of friction, while others, e.g., steel on brass, produce a friction level below what one would normally expect. Their interaction is more slippery or smooth than that of other metals, i.e., self-lubricating. No oil required. Dean Dean May cell 812.239.3359 PianoRebuilders.com 812.235.5272 Terre Haute IN 47802 ____________________________________ From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf Of PAULREVENKOJONES Sent: Tuesday, August 07, 2007 11:39 PM To: Pianotech List Subject: Re: Counter-bearing drag Hey, Dean, another myth rears it head... Brass, steel, and cast iron have quite different coefficients of friction because of the way that the surface "galls" or wears down under compression and the movement of one surface against another. What you're referring to as "lubricating" is just a way of describing the friction differentials between the materials. There's no oil, or lubricity, involved. Paul "If you want to know the truth, stop having opinions" (Chinese fortune cookie) Dean Dean May cell 812.239.3359 PianoRebuilders.com 812.235.5272 Terre Haute IN 47802 ____________________________________ From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf Of PAULREVENKOJONES at aol.com Sent: Thursday, March 05, 2009 11:07 AM To: pianotech at ptg.org Subject: Re: [pianotech] Capo Bars Dean: There is a mythology here that begs correction. Brass is not "self-lubricating". There is no "lubricity" to it at all. There is a significantly lower friction coefficient between brass and steel than between cast iron and steel particularly because of the different galling characteristics of them. Paul In a message dated 3/5/2009 7:44:29 A.M. Central Standard Time, deanmay at pianorebuilders.com writes: Young Chang started doing this in the mid 90s, don't know if they still do. They used a brass rod instead of steel. Music wire on brass is self lubricating. Dean Dean May cell 812.239.3359 PianoRebuilders.com 812.235.5272 Terre Haute IN 47802 -----Original Message----- From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf Of Richard Brekne Sent: Thursday, March 05, 2009 4:30 AM To: pianotech at ptg.org Subject: Re: [pianotech] Capo Bars Good question... and I'm looking forward to reading the replies. FTR, Bohemia pianos, a spinoff of Petrof after the splitup of Czechoslavakia actually did do this for a while... I'm unsure if they still do. They used some kind of bronze alloy I believe. Perhaps its a question of tooling and expense ? RicB Why do manufacturers harden capo bars rather than cast (or grind) the underside of the strut flat, rout out a groove to receive a steel rod of proper radius, shape and hardness and insert it there where it could, when it's worn, be easily changed and where the consistency would be more easily controlled. Is there a compelling reason not to do it that way? ____________________________________ A Good Credit Score is 700 or Above. _See yours in just 2 easy steps!_ (http://pr.atwola.com/promoclk/100126575x1219957551x1201325337/aol?redir=http://ww w.freecreditreport.com/pm/default.aspx?sc=668072&hmpgID=62&bcd=febemailfooterN O62) **************A Good Credit Score is 700 or Above. See yours in just 2 easy steps! (http://pr.atwola.com/promoclk/100126575x1219957551x1201325337/aol?redir=http:%2F%2Fwww.freecreditreport.com%2Fpm%2Fdefault.aspx%3Fsc%3D668072%26hmpgID %3D62%26bcd%3DfebemailfooterNO62) -------------- next part -------------- An HTML attachment was scrubbed... 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