<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"><head><META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=us-ascii"><meta name=Generator content="Microsoft Word 14 (filtered medium)"><style></style></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1>Thanks, David.<o:p></o:p><o:p> </o:p>Much appreciated, <o:p></o:p><o:p> </o:p>Will<o:p></o:p><o:p> </o:p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'>From: pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org] On Behalf Of David Love Sent: Monday, October 24, 2011 9:06 PM To: pianotech@ptg.org Subject: [pianotech] Making bridge caps was RE: Piano topic<o:p></o:p></div></div><o:p> </o:p>Will:<o:p></o:p><o:p> </o:p>I thought it might have been your post but couldn't find it either.  Anyway, the procedure I’ve outlined is designed to predetermine the thickness of the cap and then either plane the cap from the bottom to the desired thickness or cut it and sand it on a flat belt sander (one section at a time).  I don't like to plane the bottom of the bridge root because on a Steinway (and some others) it has a curved contour similar to the crown of the piano and it's difficult to keep that and I don’t really like to alter that.  Also, when taking material from the bottom of the bridge root, unless you are very careful it's easy to get things out of square.  Then your careful setting of the plane of the bridge cap can be ruined or you will have to make some compensation.  Moreover, the logistics of planing and checking the bottom of the bridge root are difficult when compared with premaking the bridge cap to the proper thickness in the first place.  I use this method, btw, when making any bridge cap whether laminated or not.  <o:p></o:p><o:p> </o:p>To determine the thickness of the cap I use gauges as pictured. <o:p></o:p><o:p> </o:p><img width=415 height=322 id="Picture_x0020_3" src="cid:image001.jpg@01CC9294.956DFC10"><o:p></o:p><o:p> </o:p>The larger gauge is used to determine the thickness of the cap.  It is calibrated incrementally to measure the thickness in millimeters at any given point.  The width of the gauge is equal to the average spacing between the bridge pins, about 18 mm +/-.  The smaller gauge is used as a reference for the distance bearing.  It’s calibrated the same way.  The width is unimportant.  <o:p></o:p><o:p> </o:p>The procedure is quite simple.  I do this with the bridge root already attached to the panel and the panel already installed in the piano (glued in).  However, if you prefer to do everything as a dry fit that’s fine too.  I don’t prefer that even though it’s physically a bit more challenging to do everything with the panel installed but that’s my choice.  I like to have everything glued in and set in it’s permanent position when determining bridge cap thickness and bearing.  The board at this point is conditioned (with dampp-chasers) to the lowest reasonable EMC that you think it’s likely to encounter in it’s final home.  Here in northern California that means about 35% RH.  YMMV.  I just want to be sure that during the drier season I don’t go negative.  <o:p></o:p><o:p> </o:p>Install the plate and secure it with the nosebolts and a few pinblock screws.  You should have established the plate height already.  I wedge the board down very gently just to take out a bit of slack.  Not forced down but just gently work a couple of wedges between the struts and the bridge root with a light pounding on the panel.<o:p></o:p><o:p> </o:p>Stretch your string through the capo or agraffe depending on which section.  Use the small gauge to establish your distance bearing which I set at 1.5 degrees throughout (slightly less in the bass but this is for another discussion).  Recall that the distance bearing will be sine of the angle (sine of 1.5 degrees is about .026) multiplied by the distance from the front bridge pin to the point at which the string rests behind the bridge.  If that’s 100 mm, for example, then your distance bearing will be 2.6 mm.  I’m assuming we know that.  As I mentioned, how much distance bearing to set is for another discussion.  <o:p></o:p><o:p> </o:p>Once the string is stretched through the capo or agraffe and resting comfortably on the small gauge establishing the distance bearing, you then slide the larger gauge on top of the bridge root and underneath the string until it just touches the string.  The calibration numbers at the point at where it touches tells you the thickness of the cap that will be required at that point.  If you wish you can also use a calipers to measure the distance of the string over the bridge root.  At the point at which the gauge touches the string on the speaking side, there should be a small gap at the back of the gauge.  Ideally, once the string is lowered toward the string rest it should touch the back of the bridge when it is about halfway down, thus it should do the same on the guage.  If it doesn’t you can angle the gauge to determine the difference in thickness between the front and the back of the bridge cap.  For example, if the string touches the back of the gauge at the same time as the front, you will have to angle it so that the string crosses the front of the gauge at, say, the 8 mm mark and the rear at maybe the 7 mm mark.  That tells you that the bridge cap will have to be a bit thicker at the front than at the rear.  It’s an easy way to make that determination.  This will be very usefull to know on the bass bridge where the thinning of the panel often means that the back part of the cap will actually need to be thicker than the front.  <o:p></o:p><o:p> </o:p>Make these measurements at several places in each segment of the bridge cap (3 or 4 in the capo sections and maybe 5 or 6 in the tenor section, etc.). Then you can plane your bridge cap segments accordingly and fine tune the thickness with a bench belt sander taking material from the bottom of the cap.  Once I determine the thickness that I need I actually make the bridge cap 1 mm taller than my measurements called for.  It’s relatively easy to shim up the string rests or even raise the plate fractionally (I use the WNG permiter bolt system).  It’s a pain if you find that you are just a bit too low and lowering the plate is a problem (which it sometimes is).  <o:p></o:p><o:p> </o:p>Once you have determined the thickness of the caps measure with a digital calipers the front and back side of the bridge root relative to the soundboard panel and add the thickness of the bridge cap to that and write the overall height of the bridge on the soundboard panel on both sides of the bridge.  That gives you a reference point to check your overall measurements later once you’ve got things glued up.  Don’t write these numbers on the bridge root because you will be gluing the bridge cap over them!!! (I actually did think of that before making that mistake—getting smarter)<o:p></o:p><o:p> </o:p>My own procedure (I don’t routinely use laminated caps) is to rough cut the segments to the proper thickness plus some on a band saw and then sand on a bench belt sander to the final height going slowly and measuring frequently.  I often leave it just a tiny bit high and then sand to the final height once the caps are glued on.  If you are doing a lamintated cap and your laminations are thick enough (say 3 mm or so) then you can do the same thing leaving the last .5 mm or so to be done by hand in the piano.  With laminted caps rather than the band saw it is probably easier to do the initial thicknessing with a planer cutting from the bottom until you are close to the final height and then taking them the final distance on the sander.  <o:p></o:p><o:p> </o:p>I started doing this because I hate cutting those stupid little slots in the bridge and trying to figure out when the string touches and where and at what point and going back and forth with files and all sorts of other useless implements.  Of course for laminated caps you can’t cut those little slots and must find a way to predeterine the height or plane the bottom of the bridge root.  For reasons already mentioned, I prefer to avoid planing the bottom of the root.      <o:p></o:p><o:p> </o:p><o:p> </o:p>David Love<o:p></o:p><a href="http://www.davidlovepianos.com">www.davidlovepianos.com</a><o:p></o:p><o:p> </o:p><o:p> </o:p>-----Original Message----- From: <a href="mailto:pianotech-bounces@ptg.org">pianotech-bounces@ptg.org</a> <a href="mailto:[mailto:pianotech-bounces@ptg.org]">[mailto:pianotech-bounces@ptg.org]</a> On Behalf Of Encore Pianos Sent: Monday, October 24, 2011 3:38 PM To: <a href="mailto:pianotech@ptg.org">pianotech@ptg.org</a> Subject: Re: [pianotech] Piano topic<o:p></o:p><o:p> </o:p>HI David:  <o:p></o:p><o:p> </o:p>I think it was me, and it was a lot longer than a month ago.  I can't find<o:p></o:p>my copy either.  But I would still like to ask the question.   I thought I<o:p></o:p>remembered seeing a post by you some time ago, whereby you have a laminated<o:p></o:p>cap of established thickness, and you want to set bearing to particular<o:p></o:p>values.  Since the horizontally laminated caps don't lend themselves to<o:p></o:p>planing in the fashion you would a quartered solid cap, what is your process<o:p></o:p>where you are planing the  top of theroot to set bearing, and then gluing on<o:p></o:p>the cap, ending up with a combination of the cap and the root thickness<o:p></o:p>where you arrive at the the bridge height that gives you the bearing you<o:p></o:p>want?  I don't need bearing values, but a description of your process.<o:p></o:p>Thanks.<o:p></o:p><o:p> </o:p>Will Truitt<o:p></o:p><o:p> </o:p><o:p> </o:p>-----Original Message-----<o:p></o:p>From: <a href="mailto:pianotech-bounces@ptg.org">pianotech-bounces@ptg.org</a> <a href="mailto:[mailto:pianotech-bounces@ptg.org]">[mailto:pianotech-bounces@ptg.org]</a> On Behalf<o:p></o:p>Of David Love<o:p></o:p>Sent: Monday, October 24, 2011 5:19 PM<o:p></o:p>To: <a href="mailto:pianotech@ptg.org">pianotech@ptg.org</a><o:p></o:p>Subject: [pianotech] Piano topic<o:p></o:p><o:p> </o:p>I know this is a bit off topic (it's about pianos) but somebody posted a<o:p></o:p>comment or questions about a month or so ago about putting on laminated caps<o:p></o:p>and then setting the bridge height by planing the bottom of the bridge.<o:p></o:p>Anyone have that original posting.  Don't know if it wasn't a sidebar to<o:p></o:p>another subject.  I drafted a response but didn't attach it to anything and<o:p></o:p>forgot about it until just now.  <o:p></o:p><o:p> </o:p>David Love<o:p></o:p><a href="http://www.davidlovepianos.com">www.davidlovepianos.com</a><o:p></o:p><o:p> </o:p><o:p> </o:p></div></body></html>