Pianotech

1.  Vertical Capstan Position

Posted 11-06-2017 17:22
All,

I am working to improve the touch of a studio upright due to a relatively "clunky" feeling throughout the keyboard. Several regulation combinations have not remedied the problem, and I am now considering the effect of capstan position relative to the wippen. On this particular piano, I have noticed the capstans contact the wippens nearly 3/16 inch posterior to the jack posts (i.e., toward the rear of the keys). This differs strongly from several other studio uprights that I have observed: range from 1/16 inch to 3/16 inch anterior to the jack posts (i.e., toward the front of the keys), as well as in many vertical action diagrams. I posit a significant change in leverage between a posterior and anterior positions, and perhaps a change in touch.

I ask for your suggestions, cautions, etc. of moving the capstans, other than changes to touchweight, which I understand will change proportionally to the distance the capstan is repositioned.

Paul

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Paul Piszczek, RPT
Duluth, MN

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2.  RE: Vertical Capstan Position

Posted 11-06-2017 17:25
One of the key features of the Fandrich-Rhodes weight bench system is to determine the correct capstan position.





3.  RE: Vertical Capstan Position

Posted 11-06-2017 18:00
This seems like a good hypothesis.
Try moving a few sample capstans and see if it makes things better.
You will need to adjust keydip and blow distance.

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Ed Sutton
ed440@me.com
(980) 254-7413
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4.  RE: Vertical Capstan Position

Posted 11-06-2017 18:23
Set hammer blow and key dip. Look at where the jack ends up at full dip. If it is far away from the butt, there will be an improvement in regulation with a capstan position further forwards.

Remove a few capstans and make a dummy with a round head screw and a block of wood. Sample different positions with your already set hammer blow and key dip.

The first place to start would be a 2:1 Key Ratio on a natural.

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Regards,

Jon Page
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5.  RE: Vertical Capstan Position

Posted 11-06-2017 21:01
The capstan contact point in vertical actions follows the same rules that apply to grands. Moving the capstan changes the overall action ratio (OAR). 
Changing the OAR will change the touch weight. It will also require changes to key travel relative to hammer travel. 
Measure the OAR and think this through before you start moving things around. 

ddf


--
Delwin D Fandrich
Fandrich Piano Company, Inc.
Piano Design and Manufacturing Consulting Services -- Worldwide
6939 Foothill Ct SW -- Olympia, WA 98512 -- USA
Phone 360.515.0119 -- Mobile 360.388.6525





6.  RE: Vertical Capstan Position

Posted 11-07-2017 06:18
Would the Ratio on a vertical's wippen be measured:
Flange center pin to Jack center pin / Flange Center pin to Capstan Center?

in other words, Wippen Out divided by Wippen In

Hammer Ratio:

Center pin to Strike point divided be Center pin to jack rest position on the butt leather?

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Regards,

Jon Page
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7.  RE: Vertical Capstan Position

Posted 11-07-2017 15:05
Jon, you can go through the mechanics of measuring everything. It's a good exercise. But an easier way is to simply depress the key by exactly 5.0 mm--I've made a simple tool for doing this--and measure the resulting hammer travel. (Make sure there is no lost motion!) As always I'd suggest measuring both the bass and the treble. It's not common, but I have found discrepancies.

Once you know the OAR you will have a good basis for further analysis. Since the only variable here--without resorting to major key or action modifications--is the capstan location you will now have a good idea of where to go with changing it. 

ddf 

--
Delwin D Fandrich
Fandrich Piano Company, Inc.
Piano Design and Manufacturing Consulting Services -- Worldwide
6939 Foothill Ct SW -- Olympia, WA 98512 -- USA
Phone 360.515.0119 -- Mobile 360.388.6525





8.  RE: Vertical Capstan Position

Posted 28 days ago
Thank you, all, for the helpful suggestions. In my subject piano, the AR ranged from 7:1 to 8:1, quite high in my opinion and likely the reason for the non-preferential touch. I measured AR in other pianos from around 4:1 to 5:1. I used the block from an old key-end to create a jig for measuring changes to action ratio relative to capstan position, which should make for relatively swift moves from key to key.

Paul

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Paul Piszczek
Duluth MN
218-464-0318
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9.  RE: Vertical Capstan Position

Posted 28 days ago
What kind of capstan does the piano have?
If it is a dowel capstan on a wire, it may be fairly easy to bend the wires to move the capstan to a more forward location.

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Ed Sutton
ed440@me.com
(980) 254-7413
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10.  RE: Vertical Capstan Position

Posted 2 days ago
Good thought, Ed. However, they are threaded, polished brass.
Paul

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Paul Piszczek
Duluth MN
218-464-0318
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