[CAUT] Touchweight question

[Fred Sturm]

Hi Jim, 	
	That sounds like someone didn't know what the heck they were doing.  
"Let's use wipp springs, so we don't need so much lead. Oh, my! the  
down weight is too low. Let's add lead to the backs of the keys to  
make it better." I don't know anything about Hornung and Moller  
(though my quick Google search shows that I looked up the firm in a  
European Piano Atlas about a year ago, so I must be an expert <G>). Is  
it a Danish piano, or is the name used by some Asian manufacturer? Or  
do you know?
	I'd pattern lead it.
	The more basic question? Springs can be used to moderate the amount  
of lead, but the consensus seems to be that more than the equivalent  
of about 10-15 gms DW reduction makes the action perform "strangely  
enough to be problematic." Moderating the amount of lead reduces  
moment of inertia, which means the action "feels and performs" lighter  
- easier to get it moving - regardless of DW/UW.
	It's a good idea to unhook some springs and see just how much they  
are doing. And you can adjust them to "help" precisely 10 grams while  
you're at it, and see where that leaves you with lead.
Regards,
Fred Sturm
University of New Mexico
fssturm at unm.edu



On Sep 23, 2008, at 5:51 PM, Jim Busby wrote:

> All,
>
> I have an action (Hornung and Moller 1972) that has one or two leads  
> in the very back of the key and no lead in the front. It has wippen  
> helper springs. DW is around 65 – 70 and UW is around  36 - 40 or  
> so. (Friction seems to be ok, but BW is 50 – 55!!)
>
> I don’t know why the springs were adjusted for this weight, and I  
> can adjust the springs to achieve a good weight (50-20 or so) but my  
> question is a very basic one; Why would you use springs instead of  
> leads to touchweight the action? What does this do to the MOI? Or,  
> at the very least what is the difference in feel between a “spring”  
> vs. “lead” touchweighted action? And, why do one over the other?
>
> Fred, Ric, enlighten me!
>
> Jim Busby
>
> P.s. I experimented and put weights in about 8 keys and a normal  
> leading pattern makes it work…normal.
>

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