Bridge Cap Grain Angle

[Farrell]

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Thanks for the thoughts Ron. A few comments/questions below:

Terry Farrell

Lacking better sense, I'll bite.=20

He, he, he - gotcha!

I try orient the grain in the treble=20
somewhere between parallel to the bridge in the treble, and parallel to =
the=20
bridge in the tenor. Not for compression strength, but for ease of hand=20
notching. The idea being not having the grain too nearly parallel with =
the=20
pin rows in the treble (for notching), but nearly enough parallel with =
the=20
bridge to get enough long grain on the bridge to discourage splitting =
(for=20
longevity).=20

I guess I haven't notched enough bridges to have noticed how grain =
angles may affect notching ease. So, making a notch that is parallel to =
the grain is more difficult than if the grain is at a small angle? More =
difficult because it is harder to push a chisel through the wood, or =
more difficult to get a nice clean cut? I don't have a grip on it being =
harder to push, but I can envision it being more difficult to get the =
clean cut. Which is it, or is it both or something else?

In the tenor, I go parallel to the bridge. There are two=20
reasons for this, three counting the notching concern. Parallel to the=20
bridge uses capping material more efficiently, and bridge caps don't=20
typically split and cause problems in the tenor anyway. Loose pins in =
the=20
tenor don't cause false beats like they do above the agraffe section. I=20
think it's frequency related, so it's less critical down there.=20

I'll buy that, but what does cause false beats in the tenor? I service a =
number of "good" (or should be good) pianos (Steinways, Yamahas, etc.) =
that have numerous false beats in strings in the tenor agraffe section. =
Prominent slow beats usually.

Using laminated capping stock in the treble nearly eliminates structural =

(splitting) concerns, but might aggravate notching problems.

Like I say, I haven't done a lot of notching, but I seem to recall that =
while notching my first laminated cap, I noticed the increased effort =
required (actually, I think I came to that conclusion on the first =
notch! - just to be clear, I would say that notching the laminated cap =
requires more effort, but is not too difficult).

High angle (90=B0) cross plies are hardest to notch by hand, which is =
why I thought of=20
low angle (10=B0 or so) cross ply capping as a decent compromise short =
of=20
building a power notcher. I didn't invent the idea, I just thought of it =

independently after others already had. Anyway, that's my take. Yet =
another=20
compromise.

One that makes good sense to me.

Ron N


>My understanding of bridge cap material grain angle is that is should=20
>follow the curvature of the bridge as close as is possible because =
maple=20
>is strongest regarding compression forces to application of that force=20
>parallel to the grain.
>
>So in the upper treble where the strings are roughly perpendicular to =
the=20
>bridge, this would work just fine. But in the tenor section where the=20
>strings might be 45 degrees to the bridge, does this rule hold true? =
Would=20
>there not be some advantage to having the cap grain perpendicular to =
the=20
>strings?
>
>Terry Farrell
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