New FW Formula

[Richard Brekne]

Hi PTD chums.

Whilst figuring on a few things and pushing numbers around I found that
I could come up with a different way of calculating the FW for balancing
the action.

The idea is based on the fact that I have always operated on the
assumption that you could specify both the R and BW ahead of time, and
then choose SW's to match. I like constants you see. And there are
plenty if you can rely on a R and a BW ahead of time. 

So, if you start by measureing the KR and the whippen weight WW, these
together with the specified BW will give you a new quantity which I call
BBW (Bottom Balance Weight). This quantity is a constant for the whole
action (unless you want to vary the BW for sections in which you simply
alter the constant appropriatly for each section). BBW is found by the
following:

BBW =  (KR * WW) - BW 

Given this constant it turns out the FW is given by 

FW = R(SW + (BBW/R)) 

or

FW = (SW*R) + BBW

BBW is always a negative number btw, so you have either have to add the
negative sign to the number or simply drop the sign and substract it.

Since ratio can aslo specified ahead of time (taken by measureing the
distance ratio ala Alan Vincents formula for said) this leaves you with
two unknowns for each key, SW and FW.

These are the only two quantities that should (ideally) vary over the
entire action anyways. So if you plug in a set of SW values and install
these and the resulting FW's then your specified BW should correspond to
what you get if you take UW/DW measurements for each key. If it
doesnt... (since BW is friction independant) then you have a minor ratio
problem wherever variances occur... which you can trace down rather
easily since you know its a ratio related problem.

Check it out... :)


Cheers

RicB

-- 
Richard Brekne
RPT, N.P.T.F.
UiB, Bergen, Norway
mailto:rbrekne@broadpark.no
http://home.broadpark.no/~rbrekne/ricmain.html