The aluminium skin for the elevator trim tab, and the left elevator into which the trim tab fits, both have elements that need to be bent 90 degrees in order to seal the gap that would otherwise exist.
The plans call (without much detail!) for the production of a jig which will be used to bend the skin accurately along a pre-defined line and without running the risk of cracking the metal.
As ever, the Internet is my friend, and the general consensus from earlier builders is that clamping the two parts of each folded skin piece between the bench (lower part) and two pieces of a hardwood jig (upper part) is the way to go. It needs to be done that way because the two folded pieces will eventually lie on top of one another - the upper skin overlapping the lower so that rainwater etc will flow past them both rather than accumulate within the structure.
I have a piece of oak about 1 inch thick available, and that seems just the job. Measuring the angle of the trim tab and elevator skins suggests that a wedge shape of about 15 degrees will fit nicely between the skins, and so a cut of that angle through the rectangular piece of oak, with flats at boith ends to clamp to the bench, will be just what is needed.
So the newly purchased table saw is pressed into service, and voila!
