Chef Juke wrote:
On Thu, 7 Aug 2008 09:02:26 +0300, "Rick Samuel"
wrote:


wrote in message
...
On Aug 6, 1:37 pm, Chris Friesen wrote:

You don't need either...just glue should be fine.

True enough.

You can certainly use
biscuits for alignment, but they don't help at all as far as
strength of the joint.

NOT true at all. This seems to be a widely quoted myth parroted
around here amongst the literati.

One minute of research will get EMPIRICAL research to show
differently.
You can get started he

http://tinyurl.com/6qjcu9


I disagree. I did the same test as in figure 2. Used two large,
(#20?) PC biscuits, not three. pieces were 2X4, about 15' long.
Set 48 hours with Titebone #2. I was surprised how easily they
(biscuits) broke, 1/2 in each piece of 2x4. Did not use a scale to
measure force. Nothing failed but the biscuits. I asked the
question about the difference between Lamello and PC here about a
year ago. That was not answered, but got all kinds of reasons it
failed. None applicable. After that, biscuits were for alignment,
the added strength was secondary.
I still would like to know if there is a diff between Lamello and
PC
biscuits.

Richard,

I am not sure how your test disproved the data when your test was
not
the same (2 vs three busuits) and you did not do a comparison with a
non-biscuit joint to compare amount of pressure required to break
the
joint.

Of course none of that would change the fact that you were surprised
at how easy the joint broke, but just pointing out that it was not
"the same" test and not neccesarily conclusive.

Besides that with a 15-foot moment arm he could have broken _any_
rigid joint between 2 2x4s joined 90 degrees without much effort.

The biscuits broke, he said. If it had been a mortise and tenon the
tenon would have broken. "Stronger than a butt joint" doesn't mean
"infinitely strong".

-Chef Juke
"EVERYbody Eats when they come to MY house!"
http://www.chefjuke.com

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--John
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(was jclarke at eye bee em dot net)