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Fabricating Big Bend Part 3

We had a six foot P3 stainless steel hinge to use on the 9′ brake.  From the small brake on can see the middle will bow during a bend for a thicker material.  We decided to place break the hinge up into sections.  We put 2′ in the middle and on each side we have a 9″ space then a 1′ hinge section, another 9″ space and another 1′ section of hinge.  This leave a 1″ gap from the outside edge to a hinge.

Here is Dan cutting the stainless hinge with a Dremel wheel (Always wear safety glasses when using a Dremel!! ask my Dad)

We used some stainless rivets to attach the hinges.  We used the “yardstick hinge hole template” to drill the pilot holes.  Stainless is a lot tougher to drill through than alumunim.  Dan would spot face the hinges with teh template and I used the drill press to finish the holes.  Here is four of the five hinge pieces:

Aligning the first hinge halfs with the fisrt angle wasn’t too hard.  Match drilling through the 1/4″ steel angle was a pain.  Dan used a older electric drill for this task.

Aligning the other angle with the hinge was more work.

Fabricating Big Bend Part 4

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Fabricating Big Bend Part 1

We decided to make a David Clay bending brake for the rear spars, the ailerons and the flaps.  The plans show the rear spars can be made in two peices, and joined together with a splice plate.  They did this to keep one of the parts at eight feet long, perhaps to help with a sheet size of the aluminum or shipping.  Anyways we decided to make a brake for the full 109″ long spars, that way we don’t have to have the splice plate.

Dan purchased three 10′ lengths of 3″x3″x1/4″ thick steel angle from a local supplier called Discount Steel, really nice outfit.  We alos picked up some square tubing for the handle.  He cut it to length and cleaned them up.  Really dirty work.  He had to clean up the shop after this.  Dan primed them for painting.

Notice the box of hardware from Aircraft Spruce on the workbench

Fabricating Big Bend Part 2

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Hardware From Spruce

We have been working on a long list of hardware for the Sonex.  We had ordered the tail hardware when we built it but decided to order almost all the rest all at once.  We started with a list on the Yahoo Sonextalk fourm and double checked with the lists from Sonex.  We padded the bolts by adding a few extra and getting a some of the lengths around the specified ones.

I found that Aircraft Spruce had the lowest prices by a little bit.  A couple items were cheaper at Wicks.  We made a big order and was disappointed to not get the “free shipping for more orders than $500” because it weighed more than 25lbs,  bummer. 

Here is the box that arrived with the tube behind it for the longer parts

We check the order and it was spot on with the packing list, with a couple items back ordered.  Now where to store all this stuff.

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Cleaning Up Wing Ribs

Dan & I have been cleaning up the wing ribs.  Have been working on them on and off since mid January.  The outsides have a “ever so slight bumpy” (that’s a technical term) edge after the router.  The process we have been using is:

  1. Smooth the edge with the vixen file.  (Don’t have to worry about taking off too much material since we are on the outside of the pen line and this will end up being the outside edge of rib flange.)
  2. Go over the edges with a finishing file.  This is not a bastard file, it is a first or second cut file.
  3. 180 sand paper
  4. Final with 240 sand paper or Scotchbrite pad.

The real time sink is in the radiused corners  bewteen the flanges.  I want a nice transition for the straight edge of the flange to the radius.  Looking at the light reflection on the edge you can really see the quality of the surface.

The lightening holes also need to be de-burred and smoothed.

So all this take a bit of time.

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Learning Solid Rivet Gun

We have a friend Gary in our flying club who is building an EVO Rocket.  Sweet plane, checkout the EVO website.  Gary’s fuselage is just out of the pictures.  It was motinating to see his plane.
The Rocket is a variation on the RV line which uses solid rivets.  The Sonex spar uses solid rivets and Sonex Company reccomends using a dished out bold and big hammer.  Lots of builders have done this with great results.  Gary graciously offered to lend us his rivet gun for our spar.  He gave us a lesson on riveting 101.

Gary the “Rivet Master” & Dan
Would you trust this guy with your spar?

One thing to note is that RVs use size 3 and 4 rivets.  The Sonex Spar uses size 5.  So you need a 3X or larger gun for the Sonex rivets.  If you use a smaller gun I’be been told the rivets will work harden before they are properly set.

Thanks  Gary.

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Finishing Wing Rib Gussets

After cutting out the gussets had to clean them up.  This includes filing and sanding all the edges smooth especially in the radius between to flange bends.  This is a detail where one can be really picky since the radius should be tangent where it meets the straight edge of the flange.  Here is a picture of the completed parts:

With a stack of “identical” parts you can see how consistant your flange bending is.  There were a couple that were off just a little.  I think it happened becasue I had a really small height flange clamped in the bake while the main body was being bent.  There isn’t a lot od surface area for the clamping on the little flange.  After I added an additional clamp the bending brake it was a little better.  That’s my excuse and Dan seemed to buy it…

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