Up and down weights

[Richard Moody]

Hi David
	Thanks for the reply. There are a couple of things I am not clear on. 
Perhaps you have already published something I should read first before
asking questions.  So please don't hesitate to post pointers to that.  

	An intersting process you mention is to "> Take a note and measure
Up/Down with different hammer flange frictions."  
	 I am wondering how to get those diff frictions in the same note, and how
are they measured, ,,,,,The hammer swings so many times?  or so much
weight drops the flange? 

	When you say "> Plot the results on a chart and you will see that as
hammer flange friction
> friction decreases, overall friciton decreases and  Up/Down converge." 
	
	This makes sense however there are other frictions acting on
upweight, the wippen flange and capstan against cushion for two.  Are
these
taken into account?

	 Over all then, I am  not sure how important the measurement
of up weight is, other than to indicate more or less friction  between
notes,  especially given the fact that down weight seems to be what the
action is designed for. 

My take is that friction does not change by adding or taking away weights.
 So if one considers that Dw - Uw = Fw (a quantity of friction), and this
quantity is constant, then if Dw changes, Uw must change by the same
amount. 
So regarding " just ask them to change Up/Down on an an action model to
> another of their choice.  Most would fail" ............
	I would reply, you don't really get a choice. The only things you can
change in an action are weights and friction.  You can change one but then
then you have to accept the changes in the other(s). You have to decide
which
one you want, the down weight to a certain spec, and be stuck with the
upweight.  Or vice versa.  The difference between down
weight and upweight will always be the same, unless friction changes, at
least on paper.  You can change friction  but you can't predict how much
the friction will change, you can only measure the results and live with
that.  You could change moments of levers but that would be changing the
model, and is really only a weight change.     Do I fail?  If so I have
two more pages
so you can see where I went astray ; ) 

">>>> Did you read my instructionsin my recent post for
accurately
> adjusting Turbo Wips?
> Try it.  It works.  That's what counts."<<<<<<<<

I did,  but I didn't understand why if you want a 51 g down weight why not
use a 51 g weight to begin with? In the example below.  The 58 Dw is high
to begin with before any figuring or other measuring is done.  So take 7g
off Dw to get it down to 51g, should give a measured Uw a difference of 7g
 (38-7=25). which is what you also come up with.   So no matter what you
do, friction weight (Fw) if you want to call it should  be, Fw = Dw - Uw. 
  It's 26 with 58-32 and also 51-25 that appears below.  

You said....
" >>>>For instance:

Up = 32
Down = 58

Friction = (58 - 32)/2 = 13
BW = (58 + 32)/2 = 45  (Kind of high)

lets lower the BW to 38:

New Up = 38 - 13 = 25
New Down = 38 + 13 = 51

Put a 25 gram wt on the front of the key and set the spring to lift that
Wt.
The down weight will be 51.<<<<<"

The difference between up weight and down weight is still 26. which is
logically where it should be, since you haven't changed friction, and you
are measuring weight in the same place.  All you did was change the spring
to
take some weight off the wippen.  (and  even more off if you sent it up in
a rocket) . 

	I don't know, but it looks like the two equations are divided by 2
, so the shouldn't the  2's should cancel out.?  The ratios are the
same.....  


One final question, and If I were going to Houston, ooops that is today, I
would look forward to attending your class.  If there is a video of it I
would rent it.....

You say Bw = (Dw + Uw)/2 . That looks like the average of Dw and Uw.   
And this implies also that  Bw ,  Dw and Uw would all equal when there is
no friction.  Balance weight also implies that wo friction Bw would equal
the weight on the capstan divided by 2, when the ratio of the key lever 
is 2/1.   (Bw = Cw/2)  Is this what you mean by balance weight (BW ?)?
	
	

Ric Rocket

	A test question....Would a piano play in orbit? 

	.   


	

----------
> From: David C. Stanwood <Stanwood@tiac.net>
> To: pianotech@ptg.org
> Subject: Re: Up and down weights
> Date: Wednesday, October 14, 1998 8:10 AM
> 
> 
> >> From: David C. Stanwood <Stanwood@tiac.net>
> >> Subject: Re:  Renner "Turbo Wippens"
> 
> 
> Richard,
> 
> Maybe you should do the test that opened my eyes in 1990.
> 
> Take a note and measure Up/Down with different hammer flange frictions.
> Plot the results on a chart and you will see that as hammer flange
friction
> friction decreases, overall friciton decreases and  Up/Down converge.
> Simple extrapolation will tell you that they converge on a point that is
> essentially midway between.  It's hard to say if the actual BW is
exactly
> in the middle but for practical purposes it works to making that
assumption.
> 
> The important thing is that it gives you tools and rules that allow you
to
> break up/down into components of weight and friction which may be
> manipulated to control up/down.  In other words if you don't apply the
> concept of of weight and friction components it's difficult or
impossible
> to deal with simultaneously controlling both up and down weight.
> 
> Did you read my instructionsin my recent post to Don Rose for accurately
> adjusting Turbo Wips?
> Try it.  It works.  That's what counts.
> 
> It should be on the PTG entrance exam.   If you want to embarass just
about
> any technician just ask them to change Up/Down on an an action model to
> another of their choice.  Most would fail.  I'd like to change that.
> These discussions a certainly helpful.  
> 
> David Stanwood
>