[CAUT] Renner back action

[Keith Roberts]

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
>
> -----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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