Building a Pitts 12

Kevin Kimball has made building ribs very simple, accurate, and fast. Kevin provides CNC machined jigs for each style of rib. The Sitka spruce rib chords are cut and positioned into the jig. Mahogany plywood plates are epoxied and stapled at all connections. After taking my time building the first few, it became clear you could turn this into a production task. With help from my son Aaron, we soon began cutting all the members at one time for a given type rib, and gluing them up one after the next. It was nice hot 90+ Missouri summer weather and the epoxy pot life was a little short until we started placing it in the fridge when not in use. The jigs do a great job of holding the members in position while the plates are attached to the first side. Short Dowels are positioned under the ribs at each junction that push the rib out of the jig, then plates are epoxied and stapled to the second side. The ribs look to be delicate. Most of the chords are 1/4 x 1/4 Sitka spruce and the plates are 1/16 mahogany ply, but after being formed into a truss the, end product is very strong. The instructions called for putting protective tape on the jigs to keep off epoxy. After doing this on the first jig we found it was unnecessary and time consuming. We were just careful to wipe down the jig after each use. On a few occasions we used a bit of lacquer thinner help out. There is just no getting around it, anticipation is pretty darn high at this point.