Fw: Bridge caps: box wood vs maple

[jolly roger]

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Hi Ron,
             Thank's for the added imformation.

This taken from a Schimmel hand book.

Boxwood,
SG  Dependent on growing region,  0.99- 1.02
Growing regions,  large areas of Europe, Asia, Japan and NW Himalan regions.

Asia minor and the Caucasus is the main areas of supply.
The sapwood is pale yellow, distinguishable only by it's high moisture
content,
and is very narrow.
Depending on the growing region, the heartwood is dull to a bright yellow.
The
pores are fine and widely seperated. 
The wood is extremely hard.
Regards Roger




At 05:55 PM 4/21/01 +1000, you wrote: 
>
> Roger, Dale and list,
>
> The boxwood you are referring to is Buxus sempervirens, which is a Roger
says
> much harder wood than Maple Acer saccharum.
>
> Species         Air Dry Density (ADD)
>
> Maple           0.73 gr/cc
>
> Boxwood 0.9 gr/cc
>
> I prefer to rate timber density in grams per cubic centimeter, since water
> has a density of 1.0 grams/cc. This makes understanding the relative
> densities straightforward. Wood substance has a basic density of 1.5 gr/cc.
> The wood substance in the lightest hardwood Balsa ADD 0.2gr/cc to the
> heaviest hardwood Yarran ADD 1.3 gr/cc is the same at 1.5 gr/cc.
>
> As Ron N and Roger mentioned, Boxwood is now used for the top treble
sections
> of Yamaha C series grands. Fazioli uses Boxwood for the top section, then
> Hornbeam for the next, and then maple for all of the lower string sections.
>
> Steinway Hamburg used Boxwood for the two upper treble sections until
> sometime in the 1980s. They now use maple for all Hamburg Steinway bridge
> caps. Several earlier Hamburg pianos through the 60s and 70s with Boxwood
> caps had problems. I noticed that the Boxwood they used was often
> inappropriately cut on the cross, or even slab cut in some cases.
>
> Boxwood is so fine its difficult to determine the grain direction by just
> physically looking at a bridge cap. But its pretty easy to see when an old
> cap is sawn through.
>
> I've often wondered why Boxwood bridge caps are prone to failure, but there
> are two factors on my short list of suspects.
>
> Firstly, with a density of 0.9 gr/cc, these caps would require a much larger
> drill than a maple cap to avoid excessive internal pressure. We use a drill
> 94% of the pin size for new maple bridges. This percentage would almost
> certainly split a boxwood cap.
>
> Secondly, for some years now I have suspected that the black slip coating
> which is applied to most bridges may lead to bridge damage in commercial
> usage, when subjected to high intensity lighting. The higher density Boxwood
> would be more prone to thermal damage than the lighter rock maple.
>
> Regards,
>
> Ron O
>
>
>




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