Wing Jig Part II

I decided to re-make the wing jig out of wood.  I did some rough calculation on what it would take to make it out of steel and 80/20, both were cost prohibitive.  To make the structure monolithic, I designed the main rails out of 1.75"x9.5" LVL engineered lumber and reinforced all of the joint with plywood.  The LVL's are very straight and stiff due to their tall section.  The plywood reinforcement keeps the corners tied together preventing the jig from twisting.  The idea is to make a very precise flat stiff structure to set the templates on, while supporting the whole assembly with simple adjustable legs.  

I modeled it in CAD to get measurements and angles.

These are the two 23ft long LVL's that make up the sides of the torsion box.

Here's my Dad cutting the LVL's for the cross pieces to size. One of the ends is tapered 4.5deg.

These are the five cross pieces.

All of the LVL's have been cut. The back piece is angled to allow the landing gear to clear while the wing is still on the jig.

To attach all three pieces together at the back center, we fabricated a steel T-bracket.

We drilled all of the holes with the drill press to ensure the holes would be perpendicular.

After screwing the pieces together with 1/2"x5"long lag screws we double checked for square. Looking good so far! In the background you can see the laser we used to level.

I MIG welded the bracket and sprayed it with a coat of paint to prevent any rust.

Attaching the back pieces. The green corner clamps were very handy during the whole construction process.

This plate ties the two back pieces together. The four extra holes are for the leg.

Overall, the bracket turned out to make a nice stiff joint.

Here is the completed frame.

Next we added 5/8" plywood to the top and bottom to give the jig torsional stiffness.

The 2x6 legs are attached with four screws. They have threaded inserts in the bottom and adjustable steel feet. They are extremely sturdy.

With the frame level, I attached the templates to the top using 2x4 guides. The templates can still float fore/aft and can be shimmed up/down. This view shows the relief for the landing gear.

Here is the finished jig with the wing installed. I only have the "B" and "E" templates installed for initial shimming. I will go back later and shim the "A", "C", and "D" templates.

Overall, I'm very happy I rebuilt the jig.  The old one had some nice features, such as good support along the trailing edge for installing the aft spar.   Since the spar has already been installed, the extra support wasn't necessary anymore.  The old jig did not move very well and required at least six people to support it.  Since I don't anticipate finishing the wing in this location, I wanted to be able to move the jig more easily.  

It was great having my Dad to help me with the jig.  Moving the heavy LVL's around is definitely a two person job.  He's a woodworker, so this was a perfect job for the two of us!  Hopefully he'll come back for more airplane projects in the future!