June Journal and FW's

[Richard Brekne]

Farrell writes:

>>  >Bill Ballard had written:
>> >He actually has four, with an FW Min at the base. 

>>  Ric wrote :
>>  I sure would like to see these other three.....

>Terry writes.....
>Hey, the more the merrier! Bring it on!
>

>>  Ric wrote:
>>  The one that was included with the
>>  Touchweight kit distributed by Pianotech has nothing to do with maximums
>>   really and its easy to see how they were derived. 
>
>Terry writes:
>Now what are you referring to here Richard? The FW ceiling figures? If so,
>what do you mean "nothing to do with maximums really" and how is it "easy
>to see how they were derived."

Ric replies:

The so called maximums I have in the Stanwood Table included in the kit I
bought from Pianotek are nothing more then the results of taking the Balance
equation, pluging in 38 and 9 for BW and WBW respectively, and the SW and
corresponding SWR values found on the also included Smart Chart,.... then
simply solving for FW. And as I said earlier, they also are then exactly the
amount of FW neccessary for any SW curve and corresponding SWR necessary to
create a BW of 38. The fact that this "FW" can be achieved in the form of lead
or in the form of lead combined with assist springs doesnt change that basic
picture.

Said another way... if you have an action that has a total action ratio of 5.7,
and have installed SW's that fall on that curve for this particular smart
chart, then installing these so called maximum FW's will result in the action
having a BW of 38. Any variances are due to friction variances and small
variances in leverage. (Assumes  a 9 gram WBW which seems to be rather standard
and is a minor factor in the equation anyways)

So these FW values hardly represent a maximum, or a minimum for that matter.
They represent exactly how much front weight  (whether in the form of lead,
whippen assist springs or combination of the two) that is needed to balance
whats on the other side of the balance rail pin such that a BW of 38 is
achieved.

Its easy to see this because if you plug in these these values for any given
key and solve for FW, the result is always exactly what on the so called FW
ceiling table for that key..... 

Example : SWR 5.7, BW spec 38, WBW spec 9, key number 39. You have  FW =  5.7 *
10.5  + 9 - 38 which yields a FW of 30.8. The FW table shows 30.4 and that 0.4
difference is as big a difference as you will find no matter what key you
select for any given ratio. 

Besides... in all his SW to SWR graphs he spells it out by saying "Strike
Weights to Yeild FW ceiling for given ratio"

easy :)


So.... if someone wants to say that these FW ceiling values somehow represent a
maximum that one should stay well under then one has to use something other
then the Balance equation to explain why. And as I have stated in a few other
posts, its apparent that there are a lot of varying opinions about just how
much lead is too much lead. 

I still like best David Loves comment, echoed by Bill Ballard about the
contrast between an even BW line and FW line, but that points more in the
direction whether inertia or BW should be priority rather then just how much
lead is needed. Still it does move in the direction of underlining the role
inertia plays in Stanwoods method. So how much inertia is too much or too
little is what remains the unanswered question as far as I can see.

>>
>>The other three, and how they were
>> derived would supply perhaps some answers to some questions that still
>>seem to
>> be hanging around.
>> 

I still would like to see these, and how they were derived. That might
enlighten me a bit :)


Cheers

RicB
Richard Brekne
RPT NPTF
Griegakadamiet UiB