<!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 5.50.4522.1800" name=GENERATOR></HEAD> <BODY bgColor=#ffffff> <DIV>"The larger the size difference between the two portions, the = greater the risk."</DIV> <DIV> </DIV> <DIV>Why would that be? I should think the point at which a pin would = shear would depend entirely on the metal composition (let's assume this is = constant), its diameter, and the tightness of the pin/block fit (torque). As you = make any pin size fit tighter in the block, it will get closer to its shear = point. As you make any pin smaller in diameter, you will move toward a lower shear = point. Diameter and torque - I think that is all. Why would the diameter = contrast between the top and bottom portion affect its shear strength? Is there = something about the machining process?</DIV> <DIV> </DIV> <DIV>Or do you mean (by the above quote): 'The smaller the diameter of = the top portion of the pin, the greater the risk of shearing' (because, of = course, the smaller diameter pin will have a lower shear strength, and will shear at = a lower pin torque).</DIV> <DIV> </DIV> <DIV>How would the diameter of the bottom portion of the pin affect the = shear strength? I am assuming that the rebuilder will drill/ream/whatever the = hole to a proper diameter for the diameter of the pin bottom portion. </DIV> <DIV> </DIV> <DIV>Terry Farrell <SPAN = id=__#Ath#SignaturePos__></SPAN> </DIV> <BLOCKQUOTE dir=ltr style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; = BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px"> <DIV style="FONT: 10pt arial">----- Original Message ----- </DIV> <DIV style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: = black"><B>From:</B> <A title=larudee@pacbell.net href="mailto:larudee@pacbell.net">larudee@pacbell.net</A> </DIV> <DIV style="FONT: 10pt arial"><B>To:</B> <A = title=pianotech@ptg.org href="mailto:pianotech@ptg.org">pianotech@ptg.org</A> </DIV> <DIV style="FONT: 10pt arial"><B>Sent:</B> Saturday, January 26, = 2002 5:03 PM</DIV> <DIV style="FONT: 10pt arial"><B>Subject:</B> Re: Tuning Pin = Size</DIV> <DIV><BR></DIV>Good point.  There is a slightly greater danger of = this than there would be with ordinary pins.  The larger the size = difference between the two portions, the greater the risk.  However, if the = pin is that tight, it won't be tunable anyway.  On the other hand, I = don't think I would advise a 6.75mm. top on a size 5/0 (7.45mm.) base.  I may = be overcautious, but I wouldn't go over a half millimeter difference in = diameter (= 1/4 mm. radius).  I haven't done the math on the stress = factors. <P>Paul <P>David Love wrote: <BLOCKQUOTE TYPE="CITE"> <STYLE></STYLE> <FONT size=-1>Paul:</FONT> <FONT size=-1>Because of the = difference in diameter between the coil portion and the block portion, is there = any danger of shearing the pin off if the pin is too tight in the block?</FONT> <FONT size=-1>David Love</FONT> <BLOCKQUOTE dir=ltr style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; = BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px"> <DIV style="FONT: 10pt arial">----- Original Message -----</DIV> <DIV style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: = black"><B>From:</B> <A title=larudee@pacbell.net href="mailto:larudee@pacbell.net">larudee@pacbell.net</A></DIV> <DIV style="FONT: 10pt arial"><B>To:</B> <A = title=pianotech@ptg.org href="mailto:pianotech@ptg.org">pianotech@ptg.org</A></DIV> <DIV style="FONT: 10pt arial"><B>Sent:</B> January 26, 2002 = 11:54 AM</DIV> <DIV style="FONT: 10pt arial"><B>Subject:</B> Re: Tuning Pin Size</DIV> David, <P>You are right on target.  Comments below. <P>Paul <P>David Skolnik wrote: <BLOCKQUOTE TYPE="CITE"> Paul - <BR>I think you are = right.  There has and will be plenty to discuss.  I, at least, have = already gotten the Feb issue, and also promise to read it, but some of = my concerns date back to a number of months ago when, in response = to a particular thread, you first started talking about your = pin.  One of these concerns is that, as a way of avoiding block = replacement, they are not viable if, as in many of the pianos I see, the original = pins are already against the plate, whatever their size.</BLOCKQUOTE>Yep, = there's no way my pins will back the holes off away from the plate.  = The only good solution there is a new block. <BLOCKQUOTE TYPE="CITE">Second, while I understand (I think) the = theory regarding torque and flex, I suspect that other factors, such as = lack of quality control of pins, or of the fit between pin and block = (whether new or repinned), not to mention too much or too <U>little</U> = friction between pin and sounding length of string, have much effect upon = tunability than the diameter around which the string coils.</BLOCKQUOTE>These are all extremely important, and there is = no way that my pins are designed to compensate for inadequacies in any of = these areas.  In fact, one of the cautions I include with the pins = is not to overtighten them, which is a problem I find with some restrung pianos.  My pins do not need to be as tight, because of the = reduced torque.  Furthermore, the difference between what I call = uptorque and downtorque (pulling with or against tension) is less with my pins = than with other oversize pins.  Another point is that the design = of my pins frees the diameter at the coils to be essentially independent = of the diameter in the rest of the pin.  Of course there are = limitations of strength, but otherwise very narrow diameters like 6.75mm. are = entirely feasible on a base that is as big as you want.  That's the = principle that I think would be of use to Steinway.  Finally, Klinke, = the manufacturer of my pins and regular Diamond pins makes just about = the most precise ones in the business.  I needed that kind of = precision for my pins in order to get them perfectly coaxial and cylindrical.  = Mic them all you want; they come out virtually identical. <BLOCKQUOTE TYPE="CITE"> Remember two things about pin = flex...1) It can be a very useful tool in fine tuning, and 2) it is affected = by tightness in the block.   A tight pin with no flex can = be as difficult to fine tune as a pin with too much flex, whatever its = diameter.</BLOCKQUOTE>Yes, flex can be useful, and some = manufacturers rely on it more than others in their design.  I like to minimize = it as much as possible because it compromises the pin's function as a = stable anchor, and I prefer to achieve tunability by other means, to the = extent possible. <BLOCKQUOTE TYPE="CITE">  <P>Now to read your article and find out what you really said.. <BR>  <P>David Skolnik <P>At 11:37 PM 01/25/2002 -0800, you wrote: <BLOCKQUOTE class=cite type="cite" cite="">Chances are = that at this point we get into "but what about...," in which case I get to = rewrite the whole article on line.  I would just as soon wait for = the February Journal.  There will probably still be plenty to = debate, but at least not the stuff I've already covered in the = article. <P>Best regards, = <P>Paul</P></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUO= TE></BODY></HTML>