Susan re. "Shear"

[Keith Roberts]

The dictionary I have says shear forces are two parallel forces acting in
opposite directions. The direction of these forces relative to our plane of
reference can be in any direction.
Keith R
----- Original Message -----
From: "Ron Nossaman" <RNossaman@cox.net>
To: <pianotech@ptg.org>
Sent: Wednesday, July 31, 2002 4:46 PM
Subject: Re: Susan re. "Shear"


>
> >It's obvious to me that you do not understand the word "Shear". Shear is
any
> >direction. It just depends on what plane it is in. In the case of bridge
> >pins/bridges it is horizontal shear or sideways shear. Get it?
> >
> >Joe Garrett, RPT, (Oregon)
>
> A force perpendicular to a plane produces stress at the interface between
> the acting, and the acted upon. A force parallel to a plane produces a
> shear stress at the interface between the acted and acted upon. Any
benefit
> of CA around bridge pins in an otherwise structurally sound bridge is in
> increasing compression resistance of the wood and filling the gap on the
> compression side of the hole. It soaks into the fibers and reinforces
them.
> It also is a reasonably decent gap filler under compression (as long as
> it's contained), which is, again, what it does in a bridge. CA's shear
> strength has no bearing whatsoever on it's suitability for this use, since
> there is no demand on the glue at all for shear strength. It's relatively
> poor shear and tensile strength make CA a bad choice for repairing split
> bridges, in my opinion, but there still ain't no shear on a CA glue joint
> in an un-split bridge pin hole that is of any consequence to the
> suitability of the choice of CA for the repair in the first place, no
> matter who arbitrarily says that shear is any stress in any direction.
>
>
> Ron N
>
>
>