damper lever ht.

[Roger Jolly]

Hi Fred,
                Excellent post..   I like to set the under lever to be 
horizontal at half dip, this is the point where you get the minimum amount 
of binding on the guide bushings,  I often slice the lifter felt and insert 
a card shim to achieve correct lift timing. when rebuilding an action, I 
will do a few samples and  build up the back of the keys with card 
stock,  or veneer.
If the damper levers are way low, the arc will cause a lot of back to front 
movement at the damper guide, and can cause some damper problems.

Regards Roger




At 04:41 PM 9/11/2003 -0600, you wrote:
>         If you want to calculate the optimum height for the underlever 
> center, it isn't all that difficult. Measure the height from key bed to 
> bottom of key (a). Measure from the balance hole at the bottom of the key 
> to a point in the top of the key end felt about midway within the contact 
> of keyend felt with underlever (b). Measure the height of the bottom of 
> an underlever (well-regulated) at half its travel (c). Measure the 
> distance from an underlever center to a point along the bottom of the 
> underlever midway within the contact with the keyend felt (d).
>         (c) minus (a) divided by (b) will give you the slope of the line 
> that ought to extend to the underlever center. (d) times that slope will 
> give you how much higher than (c) the centerpin should be.
>         Say the bottom of the key is at 1". Length (b) is 10". Height (c) 
> is 1 5/8". The slope will be 1 5/8" minus 1" (ie, 5/8") divided by 10", 
> or 1/16" per inch. Say the underlever length as defined is 3". The 
> underlever center should be 3/16" higher than 1 5/8", or 1 13/16". (Much 
> clearer to do these calculations in metric, and I would strongly encourage it).
>         The caveat is that this assumes the existing thickness of keyend 
> felt. It might be much more efficient to change thicknesses than to move 
> a tray up or down.
>Regards,
>Fred Sturm
>University of New Mexico
>
>
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