I made a new joint

[RicodJour]

I did visualize it, and I visualized a problem. You have tight joints, all square corners and edges, the first two pieces slide together, what happens with the third? It has to be twisted into place, and if you have exact cuts and square edges, where's the leeway to assemble it? You could undercut the joints so only the top edge is tight, but that presents other problems.

The waste is not an issue in my mind if the joint goes together. If the joint doesn't go together and fit tightly, well, then you get 100% waste!

R

[David Nebenzahl]

On 5/19/2009 11:07 AM David Nebenzahl spake thus:

Dang. Now I'm gonna have to actually make this sucker to see if it can be assembled without resorting to hammers and such.

[alexy]

I think that is structurally the same as your first joint, The shapes of the lapped pieces are different, but otherwise it is the same joint.

[alexy]

interesting:

>>> >> Came up with it while doodling designs for the tripod, but after making

I don't see the problem here, as long as the portions of the "hub" that do not have a "spoke" adjoining it are at least 60 degrees (i.e., at least as big as the spokes). If the spokes are wider than that, the last piece won't slide in.

[Tom Veatch]

I believe the 3rd piece would have clearance to slide into place along the axis of the member. I believe I see the problem you're referencing, and it would surely prevent assembling a similar 4-member joint. But 3 pieces with an angular separation of 120° should slide together quite well.

[alexy]

Depends on the relative size of the circle. The drawing is not real clear for visualizing that, but make the bulges very slight, so the circle is barely bigger than the hexagon where the (extended) legs intersect, and it won't work. Make the circle very large relative to the legs and it obviously works.

[Tom Veatch]

You are absolutely correct! As long as the radius of the central circle is greater than the width of the leg (diameter = 2 x leg width) it will assemble OK. But as soon as the radius is less than the leg width, it will begin to see interferences trying to slide that last member into position.

Numerical example: For a leg width of 1", a central circle greater than 2" diameter will allow assembly. A central circle smaller than 2" diameter, i.e. 1.5 inch diameter, will cause interference trying to insert the third leg.

[charlessenf]

"Way back in the 19-ought-80s"

Wouldn't that translate to 19080?

1908 is aught-eight, no?

[David Nebenzahl]

On 5/20/2009 6:27 PM [e-mail] spake thus:

Not to anyone with an intact sense of humor.

[Leon]

I thought 2008 was aught-eight.