You see the lower skin and the spar here.

As you could guess by now, we will rough up the upper and lower faces of the spar, and the parts of the aileron sklin that will touch the spar, with a rough sandpaper so the hy-sol can really form a good bond. We will then put the lower aileron skin in a jig and measure out just the right amount of hy-sol and catalyst to set it. We will then smear the hy-sol onto the skin in a very thin layer, and the spar in a nice tall pyramid or wedge, and press the spar down onto the lower skin. Then, after that is set, we will repeat for the upper skin, and then put an upper jig on top of that to hold the whole thing in perfect place.

This is how the ailerons go into the jig.. they will be set there with far more precision, of course, when the hy-sol is in there, the alignment clecos are installed, and the upper jig is put in place on top of the whole works.

Diesel, having checked on everyone in the shop a few times, takes some time out under my plane.