<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META http-equiv=Content-Type content="text/html; = charset=us-ascii"> <META content="MSHTML 6.00.2600.0" name=GENERATOR> <STYLE></STYLE> </HEAD> <BODY> <DIV><FONT color=#008000>Comments below:</FONT></DIV> <DIV><FONT color=#008000></FONT> </DIV> <DIV><FONT color=#008000>Terry Farrell</FONT></DIV> <DIV> <SPAN id=__#Ath#SignaturePos__></SPAN> </DIV> <DIV>----- Original Message ----- <DIV>From: "Richard Brekne" <<A href="mailto:Richard.Brekne@grieg.uib.no">Richard.Brekne@grieg.uib.no</= A>></DIV> <DIV>To: <<A = href="mailto:pianotech@ptg.org">pianotech@ptg.org</A>></DIV> <DIV>Sent: Thursday, August 01, 2002 4:52 AM</DIV> <DIV>Subject: Re: CA gluing Grand Pinblocks....My take on it/ Richard Brekne</DIV></DIV> <DIV><BR></DIV> <DIV>> > Farrell wrote:<BR>> > <BR>> > ><BR>> = > > I guess this is where I am getting hung up here... I can<BR>> > = > easily accept that there is a shear force exerted on the<BR>> > = > bridge pin getting "pinched" as it were between the<BR>> > > string<BR>> > > pushing at it from the one side, and the bridge = from the<BR>> > > otherside.<BR>> > <BR>> > I believe = the above described a compression force of the<BR>> > string toward the pin, = and a second compression force<BR>> > between the pin and the wood on = the other side of the pin.<BR>> > If the pin had been glued in, then there = would also be a<BR>> > tension force between the pin and the bridge wood = directly<BR>> > under the string.<BR>> > <BR>> <BR>> = Yes... or said another way... The bridge and string together<BR>> exert a = shearing force on the pin (ie the pin is under some<BR>> degree of shear = stress). Yet the string and pin share a<BR>> mutual compressive stress as do the = pin and bridge hole. And<BR>> tho the relationship between the bridge and pin = is much like<BR>> the nailed plate example above... the relationship = between<BR>> the string and pin is really just plain compressive force me<BR>> thinks.</DIV> <DIV> </DIV> <DIV><FONT color=#008000>Yes, unless it is glued in place, then there = would be some other forces/stresses.</FONT><BR> <BR>> All in all,,, this = adds up to the only real shear stress<BR>> involved being exerted on the = cross section of the bridge<BR>> pin exactly on the plane of the opposite = forces created by<BR>> the string pushing the pin against the bridge holding = the<BR>> pin.</DIV> <DIV> </DIV> <DIV><FONT color=#008000>Hmmmm. I don't like that. But perhaps I do = not understand.</FONT><BR> <BR>> >If the pin had been glued in, = then there would also be a tension force between the pin and >the bridge = wood directly under the string.<BR>> <BR>> There would be anyways.. = just not exerted on the glue but on<BR>> the two (parallel, lengthwise) = surfaces of the pin and<BR>> bridge pin hole. Agreed ?<BR></DIV> <DIV><FONT color=#008000>Hmmmm. Sorry, I just don't follow = here.</FONT></DIV> <DIV><BR>> Grin.... I still am not sure whether or not we are on track<BR>> with each other here or all mucked up by word usage. = Great<BR>> fun eh ?<BR>> <BR>> RicB</DIV></BODY></HTML>