Trailing edge riveting tip

[Steve]

I bought a 4 foot long x 2 inch wide x 1/4 inch thick piece of steel from Home Depot to use as the back riveting plate when doing the trailing edges on my -9A. The steel is cold rolled so you must spend some time (30 min or so) with the 60 grit paper working down to 400 in order to get the best possible finish on the surface of the steel.
Buy a 2 foot x 4 foot x 1/4 sheet of hardboard and have it sawn into 3 8 inch wide pieces. These will be used to support the rest of the control surface.
I back-riveted my flaps in 2 setups before flipping them over. 2 more setups on the top and they're finished. No constant repositioning of the plate or control surface needed.
I recommend using one of the smaller (3/4" dia.) rivet sets with the plastic no-slip ring around it when riveting the top sides. Be sure to weight the control surfaces while riveting helping to keep them flat. I doubled up Ziploc freezer bags filled with potting soil.

Starting on the tanks,
Steve