Re: [bolger] Re: destructive joint testing
That looks like a glue line failure, but maybe I can't see it good enough.
Incidentaly, if you take an unglued, unspliced piece of ply and break it
over you knee, it will break where your knee is. If you do the same with the
joint over your knee, it will break in the joint. My point is that putting
all the stress at the joint will not give you a valid test.
You should put the piece over a couple of sawhorses, with the joint in the
air between them, then apply downward force to the ends hanging over the
sides. This will apply stress to the entire center section of the board.
Doing this with fg butt joints, it always fails in the wood next to the
tape, not in the fg joint. Haven't tried this with scarphs.
Incidentaly, if you take an unglued, unspliced piece of ply and break it
over you knee, it will break where your knee is. If you do the same with the
joint over your knee, it will break in the joint. My point is that putting
all the stress at the joint will not give you a valid test.
You should put the piece over a couple of sawhorses, with the joint in the
air between them, then apply downward force to the ends hanging over the
sides. This will apply stress to the entire center section of the board.
Doing this with fg butt joints, it always fails in the wood next to the
tape, not in the fg joint. Haven't tried this with scarphs.
----- Original Message -----
From: "Chuck Leinweber" <chuck_dm@...>
To: <bolger@yahoogroups.com>
Sent: Wednesday, June 05, 2002 9:27 AM
Subject: Re: [bolger] Re: Gorilla Glue - limitations
> I just 'experimented' by breaking an 8:1 scarf joint in 1/8" luaun
> plywood. The failure was in the wood immediately next to the glue
> joint. The glue did not fail.
>
> See photo at:
>http://www.hallman.org/bolger/scarf.jpg
>
> Am I missing something? This looks like joint failure to me. The
separation was at the glue/wood interface (unless I am looking at the wrong
picture) not in the wood. If it were a good joint, the break would not
follow the joint, but would travel across the ply in some other direction.
That said, it might still be good enough for some applications.
>
> Chuck
>
>
> [Non-text portions of this message have been removed]
>
>
>
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