[CAUT] laminated bridge cap

[Ron Nossaman]

> Ron N.
> What makes the Delignit bridge cap material from Schaff hard to notch?  
> The hardness or some other reason?
> 
> Thanks.
> Tim Geinert

Hi Tim,
It's the 90°cross plies. If the grain didn't change direction 
so radically with each ply, it would notch much easier. But 
I've never used it for bridge caps. In a class I did in Reno 
(2001), I passed around some samples of capping I was making 
myself. It was about 9mm of 1.5mm maple laminations, cross 
plied at about 10°. It was tougher than solid maple, and more 
dimensionally stable, and much more easily notchable than the 
Delignit. Shortly after that, I built a power notcher and went 
with low angle laminations of commercial veneer (0.8mm), epoxy 
laminated. This stuff is tough to hand notch, but it's doable, 
and is *extremely* stable and solid. A true fiber reinforced 
plastic. From my experience, reports from the techs I've done 
belly work for, and those making their own epoxy laminated 
veneer capping, the pianos stay in tune very well, and don't 
develop false beats - so far.

The down side, if you consider it a "down", is that you can't 
do the wedge and plane routine for setting bearing with a 
laminated cap, so the bridge height needs to be pretty close 
to right when it's installed.
Ron N