Yamaha C6 key leading

[Ric Brekne]

Hi touchweight enthusiasts.

Finished a C6 a couple weeks back and I've been meaning to write about 
it. During re weighting the keys I checked all the existing front 
weights and found some fairly interesting numbers.  The factory job was 
patterned and resulted in keys being devided up into several sections 
all weighing very nearly identical.  I wrote the numbers down but I 
havent got them handy so I'll just give you the general idea.  Keys 1-20 
all had the same Front Weight... and they were heavy. 46-48 grams.  The 
next 20 keys were about 4 grams lighter which put us half way through 
the piano ... also key number 40 with a Front Weight of 42 or so grams.  
The next section was about 12 keys and again dropped by about 4 grams.  
Then sections of 6 keys each or something of that sort... each dropping 
by about 4 grams. Needless to say there was massive amounts in key 
counterbalance in the C6.  I have to assume this is pretty standard for 
the C6's of that period. 

On top of this the balance weight ratio worked out to be about 5.6-5.7.  
This thing would lift massive hammers even at a 38 gram balance weight 
spec.  The hammers I took off were really worn down and quite light the 
BW was reallly light... especially in the treble ends of each front 
weight section as described above.   I put on a set of hammers smoothed 
to a 3/4 high strike weight curve and ended up with a ridiculously light 
and extremely uneven BW.  Upon smoothing out the frontweights to get a 
40 gram BW I had to take out over 800 grams of lead from the whole set 
of keys.  40 gram BW was selected to get close to the CF III that the 
school owns.

Frankly, I love being able to re-balance actions this way and am very 
greatfull that Stanwood came up with this basic approach.  Makes 
rebalancing actions a snap and wows em every time.  It also reveals just 
how strange the factory approaches are.  I have yet to hear a good 
reason for not utilizing this approach by a factory technical 
representative....except for concerns about adding costs in the form of 
retooling, retraining, and royalties... the three R's...grin.

anyways...thought it was an interesting job and wanted to share it with 
you all.

Cheers

RicB