Hi all, I'm hoping this is a relatively simple question, but the usual Google search has not really offered me any hints ? I need to make a shaft with a connection at one end. The type of connection is not critical as the shaft it will connect to is to be specially made as well. So, I have no limiting factors of compatibility with existing components, only that of torque. The shaft must be no larger that 16mm dia. which pretty much rules out 1/2" square drive, but I would like to be able to calculate max torque on a number of different sized squares or hex's. It would only be a guess, but I would imagine the calcs to include details about contact points and / or surface area ? The maximum torque I expect to see is 80Nm Any hints would be much appreciated.