[pianotech] FW: re: Rebushing keys, was ...VS Profelt

[Ryan Sowers]

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
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