That's fantastic, Will! That one gets filed away for future reference. CB.

That is fantastic! I bet that was fun to build and enjoy.

"It is built with plates, though in this instance the plates do not act as a tension ring, the thrust is redirected and resolved at the inner ring, and tension and tension joinery was avoided to every degree possible."

Will, Could you explain in laymen terms how the thrust is redirected? Is the thrust applied to the inner octagon and posts and then through the dragon beams (is that the right term?) and bracing the thrust is reduced or eliminated?

Thanks, mo

p.s. Tim, forgot to ask what do you mean by "crab"

Mo, do you recieve Timber Framing? If so check out issues 83 and 87 and the related steeple work. I keep going over them. and am trying to get into some local churches to see how they are made.

Dragon beam is the first thing that came to my mind as I scrolled down the page. Next came hammer beam. A Yurt uses a cable as a tension ring, a whole different thing though. I see each dragon beam section as a truss and they set on the inner and outter post and stand as a simple unit. Just place them all together pointing to each other. Hey, no roof board. Tim

Here's my idea for a modified english tying joint. This is done for a dodecagon (12 sides) it would definately not work for a octagon because the angle is more acute and the spline would run out of the top plates. I'm planning a dodocagon right now with a engineer and we have opted to a hidden bolt (much to my dismay). I guess sometimes metal is stronger than wood!!

Carlos, sketch up is a great communicating tool isn't it? Did the desinging of this joint force you to go to the 12 sides as your were mentioning the spline and the angle of the plate to post would not work in an octagon? Are the splines carrying all the weight of the plates? What are the two plumb rectangles at the end of the plates? Thanks, mo

Tim, yea I have those somewhere in a stack I'll try and dig em up and take a look.

What about no boss pin and no ties? Will these work as buttresses?

Mo

The two rectangles were to be housed into the rafter to help with the weight of the top plates and counter twisting. However they were only 1/2 inch in depth in my model, even then I wasn't sure about the raising process!!

We went with 12 sides as I wanted to keep the sides at exactly 8ft in length (plywood, drywall etc..). I used a polygon calculator on the net, entered 8ft sides with about 700 sq feet and in spit out 12 sides.

By the way thanks for the explanation of how to export the 2d drawings from Sketch-Up !! I've been wondering how to do that for a while!!

Carlos