Touchweight Metrology Question

[David Love]

>Richard Brekne
>wrote:
> I'll run these numbers... and I am sure David Love will too. It will be
fun to compare what we come up with.


Richard:

Well I wasn't going to run the damn numbers but I guess you have compelled
me.

I have separated the sharps from the naturals because the ratios are clearly
different.

First looking at the naturals:

Assuming an average R of 5.5, a target BW of 38 g, Using the maximum FW, the
maximum SW based on the samples Terry has measured would be :

Note    SW

1 12.8
2 12.7
3 12.7
4 12.6
5 12.6
6 12.5
7 12.5
8 12.4
9 12.4
10 12.3
11 12.3
12 12.3
13 12.2
14 12.2
15 12.1
16 12.1
17 12.0
18 12.0
19 11.9
20 11.9
21 11.8
22 11.8
23 11.7
24 11.7
25 11.6
26 11.5
27 11.5
28 11.4
29 11.4
30 11.3
31 11.3
32 11.2
33 11.1
34 11.1
35 11.0
36 11.0
37 10.9
38 10.8
39 10.8
40 10.7
41 10.6
42 10.6
43 10.5
44 10.4
45 10.4
46 10.3
47 10.2
48 10.1
49 10.1
50 10.0
51 9.9
52 9.8
53 9.7
54 9.7
55 9.6
56 9.5
57 9.4
58 9.3
59 9.2
60 9.1
61 9.0
62 8.9
63 8.8
64 8.7
65 8.6
66 8.5
67 8.4
68 8.3
69 8.2
70 8.1
71 8.0
72 7.9
73 7.7
74 7.6
75 7.5
76 7.4
77 7.3
78 7.1
79 7.0
80 6.9
81 6.8
82 6.6
83 6.5
84 6.4
85 6.3
86 6.2
87 6.0
88 5.9

For the sharps, at an average R of 6.0 the maximum SW would read something
quite different.

Note      SW

1 11.7
2 11.7
3 11.6
4 11.6
5 11.5
6 11.5
7 11.4
8 11.4
9 11.4
10 11.3
11 11.3
12 11.2
13 11.2
14 11.1
15 11.1
16 11.1
17 11.0
18 11.0
19 10.9
20 10.9
21 10.8
22 10.8
23 10.7
24 10.7
25 10.6
26 10.6
27 10.5
28 10.5
29 10.4
30 10.4
31 10.3
32 10.3
33 10.2
34 10.2
35 10.1
36 10.0
37 10.0
38 9.9
39 9.9
40 9.8
41 9.7
42 9.7
43 9.6
44 9.6
45 9.5
46 9.4
47 9.4
48 9.3
49 9.2
50 9.1
51 9.1
52 9.0
53 8.9
54 8.8
55 8.8
56 8.7
57 8.6
58 8.5
59 8.4
60 8.4
61 8.3
62 8.2
63 8.1
64 8.0
65 7.9
66 7.8
67 7.7
68 7.6
69 7.5
70 7.4
71 7.3
72 7.2
73 7.1
74 7.0
75 6.9
76 6.7
77 6.6
78 6.5
79 6.4
80 6.3
81 6.2
82 6.1
83 6.0
84 5.9
85 5.7
86 5.6
87 5.5
88 5.4


Thus my suggestion that a wee bit of hammer weight reduction and other
adjustments to get a reasonably smooth SW curve which would keep the sharps
under maximum and result in the naturals being comfortably under maximum
(unless you are going to relocate the capstan to achieve equal R's).  Relead
the keys using the balance weight method and you're in business.  Well,
after doing all the stuff that Roger suggested to smooth out the friction
irregularities.


David Love




>Original Date below


> > #    DW  UW   F      BW     FW     KR    WW    KC     SW    R    FWT
FWC BWT BWC
> > 16   61   37  12.0   49.0   29.0   0.49   18.4   16.5   11.9   5.8
33.8   37.5   44   41
> > 17   67   39  14.0   53.0   30.3   0.49   19.4   16.5   11.9   6.2
33.5   37.2   50   46
> > 28   59   38  10.5   48.5   23.1   0.48   18.9   16.5   11.3   5.5
30.6   34.0   41   38
> > 29   73   48  12.5   60.5   17.7   0.50   19.1   16.5   11.2   6.1
30.3   33.7   48   45
> > 40   67   40  13.5   53.5   14.1   0.48   19.7   16.5   10.5   5.5
27.0   30.0   41   38
> > 41   72   46  13.0   59.0   13.5   0.50   18.5   16.5   10.4   6.1
26.6   29.6   46   43
> > 52   66   47    9.5   56.5     3.6    0.48   18.6   16.5     9.6   5.3
22.6   25.1   38   35
> > 53   68   46  11.0   57.0     8.0    0.50   18.4   16.5     9.5   5.9
22.2   24.7   43   40
> > 64   62   41  10.5   51.5     2.6    0.48   19.3   16.5     8.3   5.4
17.2   19.1   37   35
> > 65   63   41  11.0   52.0     6.7    0.50   19.0   16.5     8.3   5.9
16.7   18.6   42   40
> > 76   59   41    9.0   50.0    -1.7    0.48   18.3   16.5     7.3   5.4
10.4   11.6   38   37
> > 77   62   42  10.0   52.0    -0.3    0.50   18.8   16.5     7.1   6.0
9.9   11.0   42   41
> >
> > Action spread is right on the money at 112.5 mm.
> >
> > My SWs are right along the divide between medium and heavy hammers on
the smart chart. I should think this is a reasonable weight set of hammers.
I see someone forgot to put lead in the keys along the line somewhere! But I
also see that even if I go right up to the FW ceiling, I will be a bit over
ideal DWs.
> >
> > Not having seen all this data before, it seems rather erratic to me. How
in the world can the BWs range from 49.0 to 60.5? And that is with a very
smooth SW. I assume this is mostly erratic leading? Leading is two in bass,
one in tenor, small one near center rail in treble, and one in rear of key
in high treble. I just played around a little with weighting key #16, and I
would have to add two big leads and one small one to get near the FW Target
or Ceiling. But perhaps that is OK - basically three big leads in the bass
keys.
> >
> > Recommendations?
> >
> > I should point out here that this piano is in a small church, and it
seems that the piano is not a high priority for spending money - so I'm
probably not going to get to do everything I might want.
> >
> > I could trim all hammers, but I hate to have hammers too light for tonal
reasons. Geez, I look at this mess and start to think that I simply need to
take a saw and cut off everything above the keyframe and start all over.
Help!
> >
> > I know I can trim hammers a bit, and add lead until I get about to where
I want to go, but that seems so........ pre-cambrian. Waddaya think?
> >
> > I think I also need to regulate out a few notes to be sure that the
current geometry is not requiring excessive dip.
>
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