Quick action lubrication:

[Mike and Jane Spalding]

Hi Richard,

How does friction between the roller and rep lever/jack tip affect down weight?  Think about the "magic line".  The roller/jack contact area can only lie on the magic line at one point in the keystroke, even under ideal conidtions.  Whenever the contact area is above or below the line, i.e. at every other point in the keystroke, something is sliding.  Some actions, due to poor design or poor selection of rebuilding components, do not operate under ideal "magic line" conditions.  On my Frankestein action model, for instance, the roller/jack tip contact starts a couple millimeters above the line, and rises further above it during keystroke.  At let-off, the two surfaces have slid about 1.5 mm.   If they weren't already slicked down with Tef & Mac, I would lube them now and report the change in downweight.

Hope that makes sense

Mike Spalding, RPT
 


----- Original Message ----- 
From: Richard Brekne <Richard.Brekne@grieg.uib.no>
To: <pianotech@ptg.org>
Sent: Monday, April 08, 2002 2:08 AM
Subject: Re: Quick action lubrication:


> BobDavis88@AOL.COM wrote:
> 
> > In a message dated 04/07/2002 2:44:24 PM Pacific Daylight Time,
> > antares@EURONET.NL writes:
> >
> > >  Hi Bob Davis,
> > >
> > >  Because they are all moving parts. Center pins move in their bushings and
> > >  springs move in their spring slots.
> >
> > ***But the ones I listed are not engaged until after the jack touches the
> > regulating button. Are you measuring the downweight THROUGH letoff? Here we
> > measure only at the point the jack tender touches, which would not involve
> > the parts I mentioned.
> >
> > >  If all these moving parts move more easy (read faster, because of the
> > >  lessening of friction) the hammer movement will have less restriction and
> > >  will thus become less heavy.
> 
> Actually...grin... Bob has a nearly irresitable point here..... its going to be
> very hard to explain how these parts are involved in downweight at all when you
> first come to think of it.
> 
> If on the other hand one consistantly can measure a slight decrease in
> downweight when these things are well lubricated..... then we have a fun task of
> finding out how that could be ahead of us.
> 
> Nice... :)
> 
> 
> --
> Richard Brekne
> RPT, N.P.T.F.
> Bergen, Norway
> mailto:rbrekne@broadpark.no
> http://home.broadpark.no/~rbrekne/ricmain.html
> 
> 
>