<!doctype html public "-//W3C//DTD W3 HTML//EN"> <html><head><style type="text/css"></style><title>Re: No Power Yamaha revisited (accurate bedding adjust</title></head><body> <div>At 12:26 PM +0200 23/5/03, Richard Brekne wrote:</div> <blockquote type="cite" cite><br></blockquote> <blockquote type="cite" cite>Yes... this is the proceedure I've been using for nigh on 20 years now. Ever Since Laroy's first visit to Oslo. And as I have said, it generally has worked well, but recently I have run into 3 instruments where this was not enough. This proceedure left the keyframe bedded, with all glide bolts in contact with the frame...</blockquote> <div><br></div> <div>(?)<br> </div> <blockquote type="cite" cite> but there was lots of lost power, and lots of neighbor hammer bobbing on hard blows,</blockquote> <div><br></div> <div>"Bobbing [adjacent] hammers" is a clear indication that not all glide bolts were accurately adjusted.</div> <div><br></div> <div>I remember back about 1990 when a Steinway tech visited Sydney for a three day technical workshop. Two grands were to be regulated by a small group of invited technicians.</div> <div><br></div> <div>On the first day the usual paper shim under the bolts, lifting and tapping procedure was demonstrated by the Steinway technician, to show the locals just how it was done. I wasn't impressed since we had for some years been using our own dial-indicator procedure (which is accurate and quick - a while back the PTG published one of my documents detailing this procedure in the Journal).</div> <div><br></div> <div>On the second day of the seminar I bought in my dial indicator and wooden mounting block, to demonstrate our procedure. Sure enough, the glide bolt adjustment was 'all over the shop'. The visiting tech seemed unimpressed with our alternative procedure. It never ceases to amaze me how many folks stick with an inferior procedure just because its 'the way we've always done it'.</div> <div><br></div> <div>Anyhow, for those who may be interested in our procedure, I will take you through the process.</div> <div><br></div> <div>A dial indicator is mounted in a small wooden block with a single hole sized to create a slight interference fit with the rear plunger cover of the dial indicator (see diagram below).</div> <div><br></div> <div align="center"><img src="cid:a05100300baf46d22e4e8@[61.8.27.31].1.0"></div> <div align="center"><br></div> <div>The mounted dial indicator is used to set exactly the adjustment of each glide bolt, so that each just makes contact with the key bed. After the precise contact position has been established, each bolt is re-adjusted down a further small amount to ensure that the key frame doesn't lift the glide bolts clear of the key bed during variable weather conditions.</div> <div><br></div> <div>The procedure we use is as follows;</div> <blockquote> <blockquote><br></blockquote> <blockquote>* All glide bolts are adjusted up to clear the key bed while the touch blocks are fitted to the piano and tightened. If an action has mid section glide bolts (eg. Yamaha) you will need to remove a key over each one to enable adjustment access with the action in the piano. These also are initially adjusted to clear the key bed.</blockquote> <blockquote><br></blockquote> <blockquote>* The dial indicator is positioned right next to each glide bolt in turn, with the wooden block resting on top of the balance pins while the dial indicator plunger is depressed by the underside of the pin block (and showing a measurement which is mentally noted). The adjacent glide bolt is adjusted down until the dial indicator moves just 1 thou' or 0.025 mm. This procedure is repeated for all glide bolts until all are just contacting the key bed.</blockquote> <blockquote><br></blockquote> <blockquote>* Now repeat the adjustment procedure again, only this time adjust all glide bolts down a further 5 thou' or 0.125 mm.</blockquote> <blockquote><br></blockquote> </blockquote> <div>That's it!</div> <div><br></div> <div>The reason behind adjusting the glide bolts to a just-contacting setting, before finally pre-loading the balance rail, is that the initial 1 thou' or 0.025 mm adjustment will not cause any positional change of the balance rail which might interfere with the initial setting of the other glide bolts. The end result is absolutely accurate and, provided that the front and rear contact surfaces of the key frame to key bed are accurate, it will be quiet and there will be no 'bobbing' hammers.</div> <div><br></div> <div>Dial indicators are generally available at any good engineers supply. The one illustrated above was lifted from the Cutting Tool Mall website at;</div> <div><br></div> <div >http://www.cuttingtoolmall.com/catalog/standard.cfm?FamilyID=900100</div > <div><br></div> <div>Cutting Tool Mall is in New York state, they sell on-line, and the prices look OK. Furthermore, when used with a magnetic stand, the dial indicator can be used between the plate and the bridge as the definitive tool for adjusting the set bolts. We set-up our pianos with the set bolts just contacting the plate in its resting position. There are many uses for a dial indicator in piano work.</div> <div><br></div> <div>On my return trip from the 2001 Reno convention I called on Richard Davenport and toured his LA workshop. Richard had independently come up with the same idea of using a dial indicator for setting the glide bolts. So all roads do lead to Rome.</div> <div><br></div> <div>Best,</div> <div>Ron O.</div> <div><br></div> <x-sigsep><pre>-- </pre></x-sigsep> <div>_______________________<br> <br> OVERS PIANOS - SYDNEY<br> Grand Piano Manufacturers<br> <br> Web: http://overspianos.com.au<br> mailto:info@overspianos.com.au<br> _______________________</div> </body> </html>