Bisquit Jointer vs Dowel Pro Jig

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Somebody wrote:

Hard maple loose tenons, epoxied in place, gets my vote for simplicity and highest strength.
TiteBondII for shortest clamp time.
Lew
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The specific reference was to the recent FWW article, apparently not on your reading list. That's almost ironic, thinking back to our past conversations. Come to think of it, I don't particularly recall *where* I read it. The test featured dovetails, M&T, biscuits, and loose tenons. I'm pretty sure it was FWW, probably December or January.
Repeatable 1% variation even between two joints of the same type would be something to really crow about. If you can find a credible cite for 1% variability from M&T to loose tenon, I'll eat this keyboard I'm typing this on, every last sharp, broken shard of it, including the lead contents of its electronics. You wouldn't by chance care to restate what you wrote? I'm sure I read it wrong.
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Think about it, loose tennons are typically made out of a straight grain hard wood. The tennon sculpted from the end of the typical board very very often has been done with less than desirable grain orientation. The loose tennon is glued inside "both" pieces, not just the in the one piece so regardless of the type wood you are using you get a more consistent strength tennon.
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FWIW, the author also expressed surprise. I was more interested in the dovetail tests.
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MikeWhy wrote:

OK, let's take your particular "specific reference" then, where the strength differential is less than 3% ... doing NOTHING whatsoever to change the thrust/point of my statement.
And check those panties, Bubba ... untwisted, they'll improve your attitude/demeanor by at least that much.
--
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On Fri, 17 Jul 2009 02:43:31 -0500, "MikeWhy"
<snip>

<snip>
Don't do what you are doing right now while eating Cheetos.
They'll turn your pecker orange.
Regards,
Tom Watson http://home.comcast.net/~tjwatson1 /
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dpb wrote:

A mortise and tenon will support weight without any glue, will a biscuit joint do that?
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That's a silly question. You would never use a biscuit w/o glue. Biscuits are compressed at manufacture so that the glue will expand them for a tight fit upon *proper* installation.
So... you are asking how well a product performs when improperly installed.
By contrast the M&T joint was designed before the invention of modern glue. Back in the day, when glue could be expected to fail over time, that was a real consideration.
-Steve
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StephenM wrote:

Google "rhetorical question".

ROF,L. If you think that glue never fails you have a big fat surprise coming.
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I never say never
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StephenM wrote:

When rely on glue and glue alone to hold up someone you care about, you _are_ saying "never". And if your wife or mother ends up with a chair leg up her butt because you made the chair with biscuits instead of dowels or mortise and tenon then you will never hear the end of it.
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J. Clarke wrote:

Most modern glues are stronger than the woods we use them on, if something fails, it's invariably the wood, not the glue itself. Therefore, the consideration, as you point out, is the joints we use, we cannot put forces on the joints that exceed their breaking strength and far too many people overestimate the strength of joints because they're fast or easy. The best joints are always going to be integral M&T and dovetail, I wouldn't risk anything ending up my wife's backside by using less.
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"Brian Henderson" wrote:

Having spent a few years doing machine design in my youth, was taught to avoid depending on a weld or fasteners alone to carry the load.
As a result, joints were designed to put the material in compression and welds were designed to be in shear.
The same design concepts apply to wood and adhesives used in furniture/cabinet designs.
Glue joints are very strong when placed in shear.
Glue joints are not nearly as strong when placed in tensile loading.
Simple and straight forward, but sometimes we forget to apply the basics.
Lew
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Lew Hodgett wrote:

Further, the statement that "the glue is stronger than the wood itself" applies to commonplace species of wood glued into face grain. Gluing some of the exotics is problematical, and gluing end grain is as well. Note that in the Fine Woodworking test the butt joint was the only one that failed in the glue line.
Then there's the issue of creep--keep PVA under constant load and it moves, slowly, if the design of the joint doesn't prevent it from doing so.
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J. Clarke wrote:

If you think a M&T joint will be working after the glue fails, you also have a big surprise coming.
--
Jack
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StephenM wrote:

I agree.

I hear this all the time, and always wonder what happens when the moisture in the glue evaporates and the swelling recedes? Ideally, I would want the tenon to be stable, and the mortise to shrink around the tenon, not the other way around. I guess the glue itself could remain keeping the swelling up, but still, any moisture will eventually evaporate, and swelling should recede, right?
In other words, if the swelling DOESN'T last more than 4 hours, should I call the doctor?

Really though, glue simply doesn't work well on end grain, ergo the reason for M&T, plate, pocket screws, dowels and so on are still in use today. Glue failures cause all joints (dependent on glue) to fail, so joining techniques haven't changed joint failure rates much, but glue has. (Not sure that came out right, but I'm in a hurry)
Pocket screws do not require glue at all, and watching the TV guys apply a pint of glue (clear white glue so you can't see it when it oozes out all over your wood until you stain it at which point the folly of your ways has GOT to bite you in the ass, but not enough to keep you off the tv) always gives me pause to chuckle.
--
Jack
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Biscuits are mechanically compressed and dried. They don't shrink back to their manufactured size even after redrying in a kiln. They need to be stored in closed containers to minimize swelling from the moisture in the air.

Simplest test: wet one with a sponge and see what happens at the end of 4 hours. Try baking it for those 4 hours, just to be sure. (I haven't tried it. Just passing on my understanding of biscuits.)
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MikeWhy wrote:

I never knew this. Do they come in a hermetically sealed mayonnaise jar (asks Jack wearing his best Johnny Carson turban hat?) Seriously, a good idea then would be to store them in a mayonnaise jar, with some of that desiccant thing-ees that come with pills or packaged with some tools and electronic things. I store those small tubes of super glue gel in baby food jars or old pill containers with those things in them to keep the moisture away...

--
Jack
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I have a box of Lamello biscuits sitting in the original shipping container, a cardboard box with no liner.
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