I was thinking snug meant a close fit - not tight. But anyways, your description is nicely written. There's always room to learn new things - even with keybushings! On Fri, Apr 2, 2010 at 4:51 PM, David Love <davidlovepianos at comcast.net>wrote: > Well, it depends on the size of the key pin. The balance rail bushing, > in my opinion, should not be “snug” meaning there should be virtually no > friction there at all—certainly no squeezing. Nor should it be snug enough > to wear a small indention where the balance rail pin contacts the bushing. > Have you done a weigh off (up and down weight) measuring with a “snug” > fitting and one that is relatively frictionless? You might be surprised at > how much excess friction can be created there. Do you mean that Yamaha > specifies that the width of the bushed mortise is .008 wider than the BRP? > That’s fine but that’s not snug, that’s free by a factor of .008”. Having > done many weigh-offs with both UW and DW and calculated friction and then > going back to find the culprit I often find that the balance rail bushing is > responsible. The Spurlock cauls when fitted with the proper cloth produce a > perfect fit if you follow his instructions about how tight the dry fit > should be which is tight enough to be able to lift the key gently but loose > enough to be pulled out with relative ease. After the hot glue sizes the > bushing with water present in the glue the caul should come out very easily > as it’s only o/s by about what you mention (maybe less actually—don’t > recall). One thing to be careful of with the dry fit is that the caul is > not binding on the ends of the mortise so that what feels like a snug fit > when dry fitting is actually the caul hitting the ends of the mortise and > not representative of the fit with the bushing cloth—can happen. > > > > After I remove the cauls I go through with a single caul and test the fit > through the entire set. The caul, in my view, should slip in and out of the > mortise easily with virtually no binding (and no slop either). The insures > that you actually have the play that you need there. Afterwards you can > also then dust the bushing with dry Teflon powder to help with wear—and > don’t forget to polish the keypins (what fun). > > > > David Love > > www.davidlovepianos.com > > > > *From:* pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] *On > Behalf Of *Ryan Sowers > *Sent:* Friday, April 02, 2010 4:02 PM > *To:* pianotech at ptg.org > > *Subject:* Re: [pianotech] FW: re: Rebushing keys, was ...VS Profelt > > > > I would answer by saying "just enough". When I say snug I mean "not loose". > If you let a balance rail bushing dry with a standard .146 caul it will come > out too loose. > > Yamaha specifies .008" for the balance rail. That's not a lot. > > On Fri, Apr 2, 2010 at 3:32 PM, David Love <davidlovepianos at comcast.net> > wrote: > > What’s too loose? A “snug” balance rail bushing may not cause a sticking > key but it sure can cause a lot of excess friction. > > > > David Love > > www.davidlovepianos.com > > > > > On Apr 2, 2010, at 1:38 PM, Ryan Sowers <tunerryan at gmail.com> wrote: > > > The other thing about keybushing that I don't here discussed much is how to > make the balance rail snug enough. If you leave regular cauls in until they > are completely dry they will be way too loose for my taste. I actually > ordered a set of cauls from BiIl that are not oversized (the regular cauls > are .148"). Even so, I remove the cauls after about 15 minutes so they can > swell slightly. Otherwise they are too loose. A snug balance rail bushing > rarely causes a sticky key, and it will correct a lot of key squaring issues > making key leveling easier an quicker. > > > > > -- > Ryan Sowers, RPT > Puget Sound Chapter > Olympia, WA > www.pianova.net > -- Ryan Sowers, RPT Puget Sound Chapter Olympia, WA www.pianova.net -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/pianotech.php/attachments/20100402/c970d606/attachment.htm>
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