[CAUT] Touchweight, etc.

[David Love]

If you are trying to make a decision about whether the geometry is correct
and whether a parts swap or capstan move is needed, a quick survey a several
notes with BW, FW and SW will give you a good indication whether or not you
have a problem.  You don't really need to write it down.  You can calculate
BW in your head as you go.  Write it on the keystick.  Then check FWs on
those notes to see if you have room to add lead.  Check SWs to see what kind
of zone you're in.  Six to eight notes will give you a good indication right
away.  You might address friction issues on the notes you are surveying (a
sample, not the whole keyboard) if you feel that accuracy might be
compromised.  But I would start there.  If you see on those notes that there
is a friction problem and solving that problem addresses the weight issue
then you can go ahead.  If you discover that even with minimal friction you
still have a BW problem then you need to look elsewhere: strike weight,
leverage, etc..  I think this way is more efficient in terms of getting to a
conclusion quickly.  Balance weights won't be that much different with
friction addressed, not enough to mask a real geometry problem anyway.      

David Love
davidlovepianos@comcast.net 

-----Original Message-----
From: caut-bounces@ptg.org [mailto:caut-bounces@ptg.org] On Behalf Of Fred
Sturm
Sent: Monday, August 01, 2005 12:29 PM
To: College and University Technicians
Subject: Re: [CAUT] Touchweight, etc.

On 8/1/05 12:10 PM, "David Love" <davidlovepianos@comcast.net> wrote:

> If you measure the up and down weight on the notes you are sampling you
will
> be able to calculate the friction and know instantly whether you have a
> friction problem or not.
> 
> David Love
> davidlovepianos@comcast.net

Yes, and that would certainly be a first step in looking at an action for
the first time and doing a preliminary analysis. But it is very
time-consuming to go through the whole piano, writing all that down and
calculating BW and so forth. If you do this prior to addressing frictional
issues, it is a very inefficient approach, in my experience. For instance,
if there are major frictional issues (could be vertigris-like, could be
loose knuckle leather, felt knuckles, a number of other possibilities), the
BW one calculates from the DW and UW will not be the same as the one
obtained after addressing the frictional issues. Theoretically the friction
should be calculable from DW and UW, and within limits it is. But I have
found on more than one occasion that a piano I diagnosed as having too high
a BW from initial readings turned out to be not so bad after addressing
friction. IOW, the calculated friction was not the same as the actual
friction, and reducing it took more from the "high side" than the low (of
the difference between DW and UW). That's my experience, and is one thing
that has led me to a different approach: get the action within parameters
first, before drawing any conclusions. Charting DW, UW, BW, etc comes after
the action (or samples in the action) has had issues addressed.
Regards,
Fred Sturm
University of New Mexico



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