The Main Corner Burr

The Burr Tools Design Interface

There are thousands of ways to make a six-piece burr, but admittedly I was only looking for one.  It needed to be construct-able with reasonable methods.  In a puzzle the rod is maybe a few ounces, but in this timber frame it is about 130 lbs for a 16 foot, 6x6.  Not at all easy to manipulate 8 feet in the air.  This is especially true when you consider that in many burrs the rest of the burr has to be moved as a whole, as the parts slide together.  The other consideration is to try to find the strongest members passing through the burr joint, that will take the load of the floor joists or roofs.

Solution (in Yellow), 1 Blue, 1 Green, 2 Red, 2 Cyan

After modeling many alternatives, this is the current solution.  It utilizes vertical rods that can be braced, a main horizontal rod that locks the first pairs in place and then two other horizontal rods that lock that level in place and finally a single solid rod that slides into place which locks the whole burr.  By many standards it would not be too interesting of a burr made as a small puzzle, but it is just right at the scale of an assembled timber frame.  I sketched and modeled the burr in different ways, but one of the best ways is a software tool call Burr Tools, and I used it here to illustrate the burr I am using in the Burr Puzzle Cabin.

The solution for the burr

www.burrtools.soureforge.net

The next step is to build the burr and test the theory, which I got a chance to do during Fedex-day, which I will show in a separate post.