Can you readily calculate the increase/decrease in overall pressure due to raising/lowering pitch by, say, 5Hz? If so, assuming roughly 694 lbs at a'=440, what would be the total at 445 and 435?
Laurence
----- Original Message -----
From: David Love
To: caut at ptg.org
Sent: Friday, December 10, 2010 10:50 AM
Subject: Re: [CAUT] strange rib damage
That would be correct. It depends, of course, on how you set bearing and that may depend on the type of board and/or its condition. I often try and set bearing at the low end of the bass bridge at near zero with only slightly more pressure at the upper end of the bass bridge. Some set even more bearing at the upper end of the treble bridge than I have indicated. This is an average setting for me on the new boards that I'm doing (rib crowned with minimal compression) and I find it unnecessary, even counterproductive, to load the board more than this. In practice, at the very top of the treble bridge (last half of the upper section) I actually back off the bearing some down to more like 1 degree. The board is usually stiff enough up there without trying to achieve it by adding load and more problems come from too much stiffness or a restricting movement (jangles) than the opposite, I find.
David Love
www.davidlovepianos.com
From: caut-bounces at ptg.org [mailto:caut-bounces at ptg.org] On Behalf Of Laurence Libin
Sent: Friday, December 10, 2010 7:23 AM
To: caut at ptg.org
Subject: Re: [CAUT] strange rib damage
Just to be sure I'm interpreting this correctly, each string of trichord Note 88 exerts a downbearing of 4.423 lbs (1/3 of 13.27 lbs), roughly 3.6 times more pressure than the single string of Note 1, right? And pressure is not evenly distributed across the bridge and soundboard but much more heavily loaded at the treble.
Laurence Libin
----- Original Message -----
From: David Love
To: caut at ptg.org
Sent: Friday, December 10, 2010 9:47 AM
Subject: Re: [CAUT] strange rib damage
Here's a typical Steinway B scale and resulting lbs. This totals out to 694 lbs. The lbs on each note takes into consideration the number of unisons. Using an average setting of 1 degree for every string would produce a total of 698 lbs. HTML probably helps to keep the chart organized.
Note# / bearing deg/ lbs
1
0.25
1.22
2
0.25
1.21
3
0.25
1.19
4
0.25
1.19
5
0.25
1.16
6
0.25
1.15
7
0.25
1.11
8
0.25
1.11
9
0.25
1.78
10
0.25
1.74
11
0.5
3.43
12
0.5
3.41
13
0.5
3.36
14
0.5
3.31
15
0.5
3.24
16
0.5
3.20
17
0.5
3.19
18
0.5
3.13
19
0.5
3.04
20
0.5
2.99
21
0.75
4.99
22
0.75
5.29
23
0.75
5.41
24
0.75
5.74
25
0.75
5.85
26
0.75
6.28
27
0.75
6.32
28
0.75
6.37
29
0.75
6.62
30
0.75
6.49
31
0.75
6.65
32
0.75
6.44
33
0.75
6.53
34
0.75
6.56
35
0.75
6.54
36
0.75
6.55
37
0.75
6.52
38
0.75
6.55
39
1
8.84
40
1
8.35
41
1
8.43
42
1
8.54
43
1
8.57
44
1
8.55
45
1
8.67
46
1
8.60
47
1
8.65
48
1
8.33
49
1
8.45
50
1
8.47
51
1
8.73
52
1
8.45
53
1
8.31
54
1
8.49
55
1
8.63
56
1
8.72
57
1
8.77
58
1
8.90
59
1
8.72
60
1
8.84
61
1
8.84
62
1
8.77
63
1
8.81
64
1
8.89
65
1.5
13.23
66
1.5
13.06
67
1.5
13.12
68
1.5
13.26
69
1.5
12.79
70
1.5
12.94
71
1.5
13.09
72
1.5
13.24
73
1.5
13.40
74
1.5
13.55
75
1.5
12.92
76
1.5
13.07
77
1.5
13.22
78
1.5
13.38
79
1.5
12.73
80
1.5
12.88
81
1.5
13.03
82
1.5
13.18
83
1.5
12.51
84
1.5
12.66
85
1.5
12.81
86
1.5
12.96
87
1.5
13.11
88
1.5
13.27
David Love
www.davidlovepianos.com
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