[CAUT] Renner back action

[David Love]

Maybe.  When I install Renner underlevers I always have to cut the wire as
the post is higher, sostenuti are adjustable and upstop rails can be cut to
the proper dimension.  My comment had more to do with the tendency to
automatically look at lowering the tray (which can have its own problems for
example if it bottoms out on the dags) rather than raising the key end felt.
We tend to buy key end felt that says "Steinway Key End Felt" which comes at
a set thickness but it may be that the thickness is totally inappropriate
for that action.  We then jump through hoops lowering this that or the other
when all we really needed to do was select the proper thickness of key end
felt to begin with.  The goal is to get the bottom of the nose of the lever
on the line between the balance rail pin at the bottom of the key and the
damper lever flange when the key is depressed.  That will level the lever
most of the time and reduce friction.  That goal may be achieved by lowering
the tray or selecting the proper key end felt thickness (or both).  The
proper thickness of the key end felt is something that should be examined in
this situation.    

 

 

David Love
davidlovepianos at comcast.net
www.davidlovepianos.com 

-----Original Message-----
From: caut-bounces at ptg.org [mailto:caut-bounces at ptg.org] On Behalf Of Keith
Roberts
Sent: Wednesday, September 03, 2008 10:03 AM
To: College and University Technicians
Subject: Re: [CAUT] Renner back action

 

I would think it would affect the sos adjustment, you would have to cut the
wires, and the up stop rail might not have enough adjustment. The height of
the lever has to be set according to the tab height.

Keith Roberts

On Wed, Sep 3, 2008 at 7:30 AM, David Love <davidlovepianos at comcast.net>
wrote:

All these things are good but if the pivot is too high why not just put on
thicker key end felt?  Also, do you find that in moving the pivot pin
forward to be on the same plane as the flange center that you often need to
install a second tray spring?

David Love
davidlovepianos at comcast.net
www.davidlovepianos.com <http://www.davidlovepianos.com/> 


-----Original Message-----
From: caut-bounces at ptg.org [mailto:caut-bounces at ptg.org] On Behalf Of Jon
Page
Sent: Wednesday, September 03, 2008 5:17 AM
To: caut at ptg.org
Subject: [CAUT] Renner back action

When reworking the back action I am not concerned about the Magic Line.

My concern lies with the elevation of the pivot, meaning that I want the key
to lift the underlever parallel to the key bed. The slots worn in the
key end felt
are caused by the underlever being at too much of a downwards angle at rest.
Meaning that the pivot is too high.

This scrubbing is friction. Lifting beyond parallel is also counter
productive
because the underlever would scrub against the rear end of the lifter felt.

I also move the pivot to be in line with the flange centers. Bearing
in mind the
fore and aft placement of the top flange.

Recently, I chiseled off the end blocks on the tray and glued in a spacer
underneath them to get a good area for the new pin location. That combined
with replacing the pitman with a section of pedal rod made the pedal
depression
easier (was too hard). And now there is no discrepancy regarding the
upstop rail
between key lift and pedal lift.

When installing new flanges and end blocks, hold a flange and block in place
on a scrap piece of rail and tap the center with a hammer, this will index
the
tray pivot hole.

For the support block holes, measure the top flange center distance
from the belly rail.
This is easily done on the bench. Measure the distance from the top flange
center to the lever flange center. If the t/f/c is 6" and the center
spread is 3.5",
the new pivot is drilled 2.5" from the belly. This maintains the
position of the t/f.
And if the key lifts to 1 3/4", bottom of lever to flange center is 3/8",
that makes the new pivot height 2 1/8".    So, 2.5" out, 2 1/8" up.
Simple. It makes for a nicer feel to the touch.

Sometimes I make new pivot support blocks but usually simply place a
spacer behind them to get surface area for the new forward pin location.
If the new location is too close to the old hole, I'll drill out a
1/4" plug from
the lower corner of the block and plug the old hole (how's that for
recycling).


To ascertain to what degree, if any, dampers are scrubbing; measure the
height
of the end felt with the key depressed. Lift the underlever to that
height and look
at its angle with the keybed. If it is still at a downwards angle
then it is not optimum.
More angle means more friction.
--

Regards,

Jon Page



 

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