box joint testing

dpb wrote in news:n5bnc9$7vq$ snipped-for-privacy@dont-email.me:

That's what I was thinking of - don't woodturners commonly use CA glue to attach scraps of wood so they can hold their work on the lathe, expecting to just rap the scrap with a hammer to remove it when done? Because the CA glue is brittle and just breaks off when the scrap is hit.

John

Reply to
John McCoy
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Well, that turns out to be the same exercise here; found all around that but didn't find the particular issue.

All I'm saying is that to best of my recollection there wasn't a test of the difference between the fully-filled and the rounded mortise/squared tenon in that comparison. My follow-on opinion based on just the mechanical properties of the joint geometry is that the unfilled joint will be somewhat weaker in comparison to one of the same size tenon in racking since there's not the full shoulder to bear upon if that test were to be done.

As for the failure mode specific in the test done, I don't recall; I think cannot, however, draw too broad of conclusions regarding the failure mechanism for a joint class generally from the specific tests run therein; those results are specific to the specific joints and the specific geometry used. They're representative of those in that general size but the results could well be different, particularly on the "how" of the failure as the proportions and dimensions are modified away from those in the test sample.

Reply to
dpb

Traditionally, without a 3 or 4 jaw lathe chuck, a face plate was screwed to a piece of scrap, and brown paper from a paper bag was glued between the work and the scrap with standard wood glue. When done, you could tear the pieces apart with the paper ripping apart, not the wood. I made a ton of turnings doing this in the old days. Not sure paper bags are thick enough to do this today. I never had a bowl come off this way, wish I could say the same for the 4 jaw chuck...

Reply to
Jack

I always think there is the book guys doing tests, and real life. Sometimes (often) the so called book guys get lost in the numbers, and the fact they want to say something important. Often they are correct but meaningless in the scheme of things, and too often, they just lie.

Anyway, I've been doing cabinet work for a whole lot of years, and never once had a mortise and tenon joint fail, and believe me, not all of mine have been perfect by any stretch. About 5 years ago I made a "prototype" spectators chair out of about $3 worth of cheap construction cut offs I got at Home Depot. I designed it and redesigned it several times to get the size I wanted (had to fit at least my 280 lb body.) When I finished, it was exactly what I wanted, but was too big to fit in my Billiard room. I didn't want to throw it away, but because it was not made of hard wood, and the (internal) joinery was less than stellar, I thought a bit before giving to our local Moose, where pool is played on a regular basis, 3 nights a week traveling leagues, and patrons are often both large and tipsy. Quality chairs tend to not last long in these places.

This thing has been in continuous use there since 2010 with no signs of failing. Used either Borden's yellow cabinet glue or Titebond III, don't recall. I know chairs put the big test on joinery, more than anything, and in a bar, the supreme test. Here's the chair:

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If this thing held up, I wouldn't worry much about Domino's or square tenons in an oval hole. Glue is pretty amazing stuff.

Reply to
Jack

Love the notches for a cue stick, now it has been years since I played pool, but I don't ever remember seeing that before.

Should have carved in a name on the back of that chair. :)

Reply to
OFWW

Me, too! That is very cool.

Reply to
-MIKE-

John McCoy wrote in news:XnsA57895FF5F927pogosupernews@213.239.209.88:

From the FWW Issue 203...

The test was for diagonal compression (racking force.) All results in pounds. Half lap 1603 Bridle 1560 Splined miter 1498

3/8 M&T 1444 3/8 floating M&T 1396 Miter 1374 3/8 wedged M&T 1210 3/8 pinned M&T 1162 5/16 M&T 988 Beadlock 836 Dowelmax 759 1/4 M&T 717 Pocket screw 698 Domino 597 Biscuit 545 Butt 473 Cope & stick 313 Stub tenon 200

There ya go...

Reply to
Larry

If I am reading this correctly a Butt joint was shown to be stronger than a stub tenon and cope and stick...

Bonjour!

Reply to
Leon

More for pen assembly and also used as a finish on lathe projects like pens.

Reply to
Leon

Leon wrote in news:mtadnWfoM- snipped-for-privacy@giganews.com:

Well, cope & stick and butt joint are both long grain to end grain (since they were doing right angle joints). I'm going to guess (since I still haven't found that issue) that their butt joint had a lot more glue area than their cope & stick joint.

No idea why the stub tenon did so poorly.

To Jack's point, I'm going to guess that all our experiences say any joint over 750lbs-force or thereabouts is ample for most any use we're going to put it to.

John

Reply to
John McCoy

dpb wrote in news:n5cavv$o5t$ snipped-for-privacy@dont-email.me:

You're probably right. I have it in my mind that that was tested, but it was probably somewhere else and I'm conflating two different articles.

This is exactly what I was thinking.

John

Reply to
John McCoy

I use it for trim corners, crown, etc. I also use hot glue but CA is a bit cleaner and sandable.

Reply to
-MIKE-

Ditto.

Keep a bottle of the thick CA in my trim/install toolbox, as CA glue is great for attaching trim pieces that have already been stained/finished.

Reply to
Swingman

The Spectator chairs for pool matches are known as the "Electric chair" because as long as you're sitting in it, your opponent is kicking your ass, IE, killing you. I thought about that but I don't carve and it was just a prototype.

As far as the notches for the cue stick goes, that's common for this type of chair, however, when I made the holes, using a forstner bit, I should have made it easier for the cue to release from the hole. As it stands, some drunk must have tripped on a cue in one of the slots, and broke off the a small piece of the arm. If anyone makes a similar chair, keep that in mind. You don't want the cue to slip too easily out of the notch, but then you want it to come out easily if some ass trips on the cue.

Reply to
Jack

That's interesting stuff, but, I have some serious questions on some of it, most of it the more I look at it. For example, a floating M&T is way, way stonger than a Domino? I thought a domino WAS a floating M&T??? A splined miter is really strong, I don't think so. A butt joint is not even really a joint, imo. A butt joint needs dowels, pocket screws or something to make it a joint. Gluing two pieces of wood together with end grain doesn't work, so what on earth were they talking about? A 3/8 M&T is a stub tenon, and pretty much a cope and stick, for the most part, so again, it's not clear to me what they are doing. A miter joint is stronger than a domino? Really? A miter joint is the weakest joint I know of, other than a butt joint.

Can't wait to see what Leon thinks of this list, particularly the domino joint being near the bottom of the list. Hogwash I say:-) Who made this list, Scott Phillips?

Reply to
Jack

I've been trying out Nexabond.

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Basically a CA glue with much longer open time-- minutes instead of seconds. The jury's still out as I haven't used it enough to form a valid opinion.

I did use it on some stairway handrail returns a few months back. I just glued with Nexabond, no trim screws or nails. It's on a friend/client's house and I asked him to be my guinea pig for the stuff. He's going to let me know if/when it ever fails and I'll come over and inspect/repair it for free.

Reply to
-MIKE-

It's on the Internet, it's got to be true, eh?

AAMOF, Leon already made his feeling known with "Bonjour". (think: French Model)

Reply to
Swingman

Well not really, all things being equal. My cope and stick and stub tenon joints typically have a minimum of double the glue surface area than a simple butt joint.

If it is too shallow it could be a problem but mine are always 1/2" deep so I am getting 1.75" square inches of glue surface area per linear inch.

A little more about different types of joints, when wood pieces mate and they interlock they also self align. With plain butt joints and or pocket hole screws you have to be cautious that the outer exposed surfaces of the joint end up on the same plane.

Reply to
Leon

Actually, it can work pretty well. With thickened epoxy.

Reply to
dadiOH

I thought a domino WAS a floating

My thoughts exactly Jack, a Domino is a floating M&T.

In fact a Domino or floating tenon may ever be better than a plain M&T. Often the end of a board that you are going to form into a tenon might not be suitable if it has a knot or strange grain.

A splined miter is really strong, I don't think so. A butt

LOL.. Scott Philips or that other guy on TV that insisted on calling his SCMS a RAS.

Reply to
Leon

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