Overs Action (was aptta conv)

[Ron Overs]

Richard Moody wrote,

(re the action drawing at www.overspianos.com.au/actn.jpeg)

>    Interesting pictures.  Is that a spring adjusting screw just behind the
>wippen flange?  ---ric

Yes, it is there for 'fine tuning' the tension on the wippen helper 
spring. The upweight/downweights (43/53 with a 10.5 gram hammer) of the 
prototype models, were achieved with one 1/2" key lead only.

Some technicians may prefer to use two leads with less assist spring 
pressure, since the higher the spring pressure, the less reliable will be 
the catching of the hammer tail during soft playing. However, we found 
that the checking was acceptable with one lead weight only in our models 
(we used a 10.5 gram hammer only for the action development since we were 
interested in looking at the worst case scenario - the bass).

There are slight action efficiency benefits to be had from the employment 
of assist springs in conjunction with less lead. Apart from the obvious 
reduction in key inertia, the assist spring is able to partly support the 
hammer through one friction-pair only (the jack/knuckle), whereas any use 
of extra key leads will be required, as a consequence of their location 
in the key, to partly support the hammer through two friction surfaces 
(the capstan/heel plus the jack/knuckle).

The repetition lever spring is also adjustable with a similar grub screw. 
We used 3mm metric hexagon socket grub screws for our prototypes (these 
require a 1.5 mm Allen key for adjustment). I feel inclined to use them 
in the production version also.

Any preferences out there list, between the traditional blade screw type 
set screw and the hexagon socket type?

Ron E. Overs


Overs Pianos, Sydney Australia
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Email:   sec@overspianos.com.au
Website: www.overspianos.com.au
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