The connection between the end’s of the fork branches and the top chord members has proved the most complex to detail. In the first prototype we had a rectangular mortice and tenon but this proved tricky visually (a lot of the mortice’s surround flat was exposed) and in engineering terms, as it is difficult to get the needed contact area. Instead we have develop an elliptical-conical tenon which best achieves the compression contact area and fits nicely. To prove this we worked up a version manually (using Charlie’s hand skill!) and then with the robot arm.