Thursday, June 7, 2012

Elevator Hinge Straps

 With the hinges welded on the last thing needed to make them work is the strap for the outboard hinge.  The strap is made of .050" steel 3/4" wide.
 The strap holds the elevator spar in the hinge block.  It gets bolted to the stabilizer with a 3/16" bolt.  The center hinge does not get a strap.  The inboard hinge socket we've discussed already.

 I made a pattern from card stock to work out the length of the strap and the made it 1/8" longer.  It's easy to trim off the extra once the straps are done.  I used a piece of 1" tubing clamped in place to locate and start the "U" bend in the strap.  The strap was bolted to the block and the center of the elevator spar marked as a reference for the start of the bend.  To assure the ends of the "U" line up I squared the strap to the spar.

 To hold it in place and keep the strap flat to the start of the bend I clamped it to the hinge block.  I then bent it around the tube until it hit the clamp.  You can see here that it springs back so that it is not close to the tube.  To get the correct 1/2" radius for the bend  I then clamped the strap to an 11/16" deep socket (about 7/8" O.D.).  To finish the bend it's just a matter of making sure the bend starts at the line and the legs end up parallel.

 With the strap in position so there is about 1/64" - 1/32" play in the tube The bottom hole center was marked with a 3/16" duplicating punch.  A little care is needed to make sure the drill locates the punch mark.

I need to trim off the 1/8" excess on the second end.  They came out great.  I can swap them to either elevator and they fit the same.  Very nice.  Now I need to add the bushings for the stabilizer brace wires and the tab for bolting the front of the fin to the front spar of the stab.

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