I made a new joint

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Actually discovered a variation of a joint I discovered some time ago.
Way back in the 19-ought-80s, I invented a 3-member lap joint trying to join three stretchers on a small table (I made the joint but never finished the table). It was published by /Fine Woodworking/ in their "Methods of Work" column, and later included in a couple of their collections of /Proven Shop Tips/:
http://www.geocities.com/bonezphoto/wood/3-memberLapJoint.gif
Just a few days ago I sat down to design some parts to the wooden tripod I'm building, and remembered this joint. However, after making some sketches and a cardboard mock-up, I realized that this joint could be made much more simply:
http://www.geocities.com/bonezphoto/wood/3-memberLapJointNew.gif
While the original joint is stronger since it has a larger glue surface area, the new variant is much easier to make. In fact, I did the whole thing on the table saw, where in the original joint you have to chop out half of the waste. And I'm not the best wood-chopper-outer in the world, I'll admit. Hard to keep those surfaces flat enough for gluing.
The new joint is an interesting little puzzle that I haven't completely figured out yet. Because of its asymmetry, it needs to be made oversize to cover the needed width. The finished joint looks nice, though not as interesting as the original with its angular inlets.
--
Found--the gene that causes belief in genetic determinism

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I like the original design, too. It's got a Chinese/Japanese flavor to it. Seems to me you could use a jig and router and knock out either joint fairly easily with just a little bit of handwork.
Are you still in Flagstaff? I rode through there on my bicycle on my way cross country back when your Methods of Work tip appeared. Great area.
R
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"Way back in the 19-ought-80s"
Wouldn't that translate to 19080?
1908 is aught-eight, no?
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On 5/20/2009 6:27 PM snipped-for-privacy@gmail.com spake thus:

Not to anyone with an intact sense of humor.

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I thought 2008 was aught-eight.
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David Nebenzahl wrote:

I like it!

Neat, but not as pleasing (to me) as the original.

Sometime over the summer (or perhaps next winter) I think I'll have to try writing a short CNC router program for a close variant of the original. It's just too interesting to not try! :)
Thank you for sharing both joints.
--
Morris Dovey
DeSoto Solar
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On Sun, 17 May 2009 17:27:20 -0700, David Nebenzahl

You say you've actually made the new variation of the joint using a table saw? How about posting a picture or a dimensioned sketch of the side not shown in the sketch in your link. A Sketch-Up model would be preferred.
I agree it's a puzzle. I've failed so far to lay out an arrangement that can be cut with a table saw where the side not shown in your sketched plan view isn't full of gaps, voids, and/or mismatched edges.
Tom Veatch Wichita, KS USA
An armed society is a polite society. Manners are good when one may have to back up his acts with his life. Robert A. Heinlein
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Tom Veatch wrote:

Good catch - I fired up DesignCAD and confess that I couldn't make the geometry (as drawn) work either. Perhaps Dave is remembering another joint...
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Morris Dovey
DeSoto Solar
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Actually, the second joint does work. I will post an AutoCAD sketch on ABPW. :-)
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I was successful in posting a pdf of the joint. The joint needs to be modified in order to fill the voids. That would be easy to do. I'm not sure it could be done on a table saw.
The sketch shows a single part and then three parts assembled. And then I showed a rotated view of the same assembly.
I think it is an ingenious solution.
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Lowell Holmes wrote:

Me too - but when I tried to do the modification (by shifting the "center" toward the side), I still couldn't make it work. I'm not certain that I couldn't have done better with another cup of coffee, but...

I think the original joint was the truly ingenious one. So ingenious that I've stashed it in my "must try" collection (even though I don't build furniture).
--
Morris Dovey
DeSoto Solar
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I don't disagree with you at all.
I tend to try keeping things simple. I might very well use the second method and glue blocks in the void. You could also taper the boards to fill the void. You might even make it a design element.
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R
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wrote:

Obvious solution - get a bigger cup. ;)
R I tried that also. I think the original joint with some hand work is the way to go. It would not take much time at all to do. I may go to the shop and try one just to see. If I do, I will post a picture.
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wrote:

Obvious solution - get a bigger cup. ;)
R I went to the shop and made a rough try at David's original joint. I had to make a slight change from what my understanding is, but it did make up. The work I did is rough and not close tolerance, but you can see the joint works. I posted photos in abpw news group.
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On 5/18/2009 12:58 PM Lowell Holmes spake thus:

>

>>

Now that you've made it, you should try to make some variations with n members (4,5,6, etc.). It'll work with any number of pieces (well, within reason).
I'm just afraid that the 4-member one will have a center that looks like a swastika ...
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On 5/18/2009 7:09 AM Morris Dovey spake thus:

Thanks. Since you like the design, you might find this variation interesting:
http://www.geocities.com/bonezphoto/wood/3-memberLapJointCir.gif
Came up with it while doodling designs for the tripod, but after making a mock-up decided it was too much work for this project. I like the circular motif.
Put that in your CNC program and smoke it!
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How would you assemble that joint? It seems that you'd need fairly loose fitting joinery and fairly thin pieces.
R
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Not to mention the amount of wasted material to make it (out of one piece)
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Hmmm. You've given me an idea. Just scribe some lines on some wood to make the joinery look complicated. Sure would be easier.
R
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