Video on joint tests

This type of video is right up my alley. I like testing that has measureable results, and in this they even spend a couple of minutes on the biscuit.
After watching though, it looks like I may have to buy a new doweling jig!
And I knew the mortise and tenon was strong, but not that strong. I would certainly think at least some credit would go to today's adhesives. I think this video ties in well to an earlier thread where there was concern about using glue only in construction.
http://tinyurl.com/yto5av
I am sorry I missed the magazine when it came out.
Robert
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On 21 Mar 2007 11:59:36 -0700, " snipped-for-privacy@aol.com"

That was a pretty impressive video. Thanks for the link. I'm curious how dovetail joinery would compare.
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wrote:

Interesting link. I could watch stuff like that all day.
The tests were setup a bit oddly. The force in the "shear" test is being applied at some distance from the actual joint, so it is not really a shear test, so much as a test in bending. They also test a dado as in a shelf connection, then follow it with a face frame test. That's misleading and the numbers have nothing to do with one another. The face frame joints tested in the "shear" test are very strongly influenced by the moment. In other words, the distance between dowels would have a large effect on the joint strength, and that skews the results making it difficult to really compare two different types of joints. I know that real life forces are rarely entirely shear or entirely bending moments, but the forces are limited. A shelf or face frame rail presumably has a connection at either end, which would limit the amount of bending stress the joint itself would experience.
I'm surprised that they didn't make the test pieces more accurately model real world stresses so that the test result numbers could be applied to something. I already know a mortise and tenon is the strongest joint, but how much stronger than another type of joint in the same construction is the question The tests should have been conducted on face frame mockups and shelf mockups and not isolated joints. I'd hope the complete sequence of testing would have more comparable results.
Still, interesting stuff to watch. Thanks for posting the link.
R
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Do you have any opinions about the test result posted at http://www.dowelmax.com/test_results.htm ?
Its obviously a singular test aimed at showing the dowel joint compares favorably to mortise and tenon. I have yet to see any test or claim to say that there is any joint stronger than M&T, but many applications are served well with something easier than a traditional M&T joint. I am a very big fan of the dowelmax jig. My pocket hole jig and biscuit joiner are gathering dust since I got it. Of course, I don't need production speed/efficiency either.
Bob
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wrote:

This brings back memories. I did a lot of testing, under controlled conditions, of corner joints in box manufacturing. My interest was in how one vibrating side transferred energy to an adjacent side in a loudspeaker enclosure. The amount of flexing that goes on, as captured by high-speed strobe and camera combos is fascinating. So was this video. We never tested for ultimate strength. I love stuff like that. All it needs is Scarlet Johannson to do the show and tell.

then average them all. That would give us a somewhat better feel for the joint itself, not the limitation of the wood used. Oak likes to split, maple not so much...etc.
Thanks for that, Robert.
r
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Robatoy wrote:

Set a strobe at about 6-8 Hz in a dark room and watch out.
Brain goes into resonance if you stick around too long.
Lew
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me...
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