Unless you're a carpenter, you probably haven't heard of the "45 degree rule." Here's how it works. the clamp forces the force applied to the triangular section of wood at a right angle of 45 degrees to each side of the corner cross section. In order for the force to be applied as much as possible to the entire fastening joint, the clamps should be placed so that the force triangles coincide. This is a particularly handy rule for the carpenter who wants to justify buying more clamps. There are never too many fasteners. But really?
The short answer given by [ari kardasis] in the video below… sort of. With the help of incredibly sophisticated strain gauges and a Raspberry Pi, he discovered that things are not so simple. Each part of the load is placed in a 3D-printed bracket that places the sensors evenly on the tree under test, and a lot of work is required to make the test rig as strong as possible with steel reinforcement. There were a few installation issues, but once that was sorted out, the test rig was up and running.
(Ari) tested the distribution of compressive forces on both hardwood and softwood logs with different widths. In general, he found that the power structure was wider than the 45 degree rule suggested, in some cases it was more than 60 degrees. The soft had a slightly different pattern than the hardwood, but it was still more than what was seen in the tutorial. Finally, two board widths between the handles will be sufficient for hardwood, and 1.5 or more for softwood. Either way, that means fewer clamps are needed.
Most woodcutters are bulls, so it's good to see serious analysis like this. This reminds me of [Matthias Wandel's] experiments with different types of wood and resin.
