Sonex 1404

Posts Tagged ‘pivot

I completed the aileron control horn assemblies. This includes the horn and pivot assembly, installed on the aft ribs on both the right and left sides.

I gathered all the parts. This includes the channels, clips, control horns and the pivot base along with the phenolic sheet. I have the machined angle kit, and I recently sprang for the pre-drilled angle kit, so most of the work is already done.

The first step was to cut the phenolic spacers to size. I had heard horror stories about cutting phenolic, but the band saw did easy work of this. I cleaned up the edges with the sanding belt.

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Next step was to drill the bolt holes out to the proper size. I did this is steps with the 3/16″ reamer used last.

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After ensuring a snug fit, the next task was to insert the brass bushings into the 7/16″ holes that were already drilled. The plans call for a press fit, and after getting some tips from the Sonextalk group, I soaked the bushings in a bowl of ice cubes, and the pivot base in some boiling water. I made a wooden spacer so that I could get the clearance while pressing the bushings in with my bench vise. You can see the spacer between the pivot base and the right side jaw in the second picture below.

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The result was a set of pivot bases with perfectly press fit brass bushings. The spacer was made of soft wood, so it deformed and I threw it away. It served its purpose very well.

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The next step was to assemble the whole thing. The plans call for the pivot bushings, bolt and steel bushing inserts to be lubricated by white lithium grease. Also, the castle nut has to be just tight enough to ensure free movement of the bell crank. I set it at the tightest it allowed me to insert the cotter pin while ensuring free movement.

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After this, I assembled the mounts for the entire assembly on two aft ribs. This goes between the forward two lightening holes, with a pair of channel stock on the other side.

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The channel stock go on the outside for the right hand rib and on the inside for the left hand rib. I mistakenly placed the channel on the outside for the left hand side too and drilled all the holes. Unfortunately, the holes didn’t line up when I put the channel back on the inside, so I decided to throw away the rib and start over. I ordered a replacement rib from Sonex. That was a $30 (plus shipping) mistake.

I riveted everything together to get the final result.

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I have to decide what to tackle next – whether I should go ahead and assemble the ribs on the spars and complete the wings, or finish the flaps and ailerons so that I finish up the smaller tasks. I’ll think about it a little.

 

 

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