On Thu, 07 Aug 2008 21:27:03 -0500, dpb <none@[EMAIL PROTECTED]
> wrote:
>Tom Watson wrote:
>...
>> My point, and I would say, my premise, is that the act of gluing
>> introduces some deterioration to the fibers along the line.
>...
>
>I don't follow that line of thought at all -- why would any
>_deterioration_ cause a failure away from the glue line? And what
>mechanism is supposedly at work doing this?
>
>I think your proposed test (iiuc) will simply again demonstrate the
>point of maximum stress is in the middle of the panel and the variation
>in wood properties will make for a moderate difference in actual
>breaking point from one side to the other a la Heisenberg...
It seems to be the case in all of the experiments available on the
Internet that the premise, "stronger than the wood itself", means that
the tester accepted the fact that the wood failed, not on the
glueline, but in an area adjacent to the glueline. The test panels
all had a single glue line and the force was applied to the center of
the panel / glueline.
In the real world what we worry about is that there will be wracking
forces around the perimeter of the panel where it is enclosed by the
frame.
I would propose to create two series of three test panels that have
four glue lines / joints in them. Two glue lines will use biscuits
and two will be rubbed and butted. The panel will then be clamped and
allowed to sit overnight.
The critical difference in this test will be that the force is applied
to the center of the panel and that no joint will be any closer than
two inches from the centerline of the application of force. In other
words. the force will be applied to undisturbed wood, rather than
directly on the glue line.
The second test will apply stress to the edges of the panels,
mimicking the forces of a wracking panel against an unyielding frame.
Now, I only have a bathroom scale available to measure the force but
that should be enough to prove the thesis, or not.
Regards, Tom.
Thos. J. Watson - Cabinetmaker
http://home.comcast.net/~tjwatson1/
tjwatson1ATcomcastDOTnet
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