To fix the rudders to their posts so that torque is transmitted plan A was to drill through each rudder and post at two places, tap through both @ 2mm, and secure with 2mm screws. Great plan, scuppered by not being able to drill the stainless steel posts! However, they file quite easily (isn't that strange), so plan B was to make flats for the screws to bear on, as can be seen above.

This is less satisfactory for two reasons. One is that as these are not grub screws the length has to be finely judged so the heads do not protrude excessively (just for appearance sake). The other is that the threads are tapped in a bit of whitemetal and a bit more epoxy (I did put extra epoxy in where these screws were to be) neither of which can be classed as strong in terms of screw threads. So there is limited force available against the flats.

I have a plan that could somewhat improve this situation, but for now I am actually using 2mm nylon screws and the trial fits (per picture) do suggest that the retaining force is adequate, so I will go ahead with this for now. The screws as seen above are a tad too long still, so I will take another half mm or so off them at final fitting.

Next step is to go back onto the makers installation sequence and fit the rudder post top bearings.