Saturday, November 21, 2009

Elevator Jig & Fabricating Parts

Before I started on the tail surfaces I took all the various drawings I had and the existing surfaces and created a drawing which is as close to exact as I can do. All the drawings were made after the plane was built. I have only found 2 drawings for the NINE which were drawn before my plane was built. They are for the radiator and are in the Rome Turney Radiator Company collection of the Rome, New York historical society. They exactly agree with the later production drawing of November 1930. The jig board was laid out from my drawing and was done to allow both the stabilizer and elevators to be made with one jig. The cut outs are to allow tack welding with a torch. I know there are great new welding methods and equipment. If it were a safety issue I'd go with the new methods otherwise using them misses the point of this restoration hobby.

Because the ribs pass above and below the spars I wanted the spars, leading edge and trailing edge tubes all on a plane parallel to the board. To do this and hold the tubes in position for tack welding I made these blocks which have the same distance from the board to the tube centerline. They were made by drilling the holes for the different size tubes in a simple jig and then sawing them through the holes. They are screwed to the jig board so they can be removed as needed to make the different surfaces.

The first task was to make the trailing edge from 5/16" tubing. I started with the bend which would be the hardest to get right if not done first, the small bend at the inboard end. This was done with a simple tubing bender which had the needed bend radius. This bend was used as a reference point as the rest of the tube was bent while being held flat on the jig board. That's why some of the weld cutouts were still screwed in place. They contained part of the curve for the Trailing Edge tube.

To make the larger bend I made a simple wooden bender with a large radius to get smooth bends. The radius is still significantly smaller than any on the tube. I worked from the inboard end out making very small bends while holding the tube flat on the jig board. The first one took about a half hour and the second twenty minutes.

Next the outboard end of the spar was flattened and filed to fit the trailing edge tube. This was done first because it is easier to locate and drill the hole at the inboard end then it is to flatten the tube.

The inboard end of the spar was marked for the Trailing Edge hole by rubbing with a small square. The hole was drilled through the spar and the Trailing Edge tube will be trimmed off after tack welding.

The tubes are held in the jig blocks with a piece of plumbing strap held down with the mounting screws.

The rest of the pictures show details of how the original elevator was welded together. Starting with the inboard end joint of the spar and trailing edge.

The next 2 are of the Spar to Trailing Edge joint at the outboard end.

The next 3 are of a typical Rib to Spar joint.

These 2 are of a typical Rib to Trailing Edge joint.

The last is of the elevator control horn and 3/4" tube rib.

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