Main Spar SNX-W08

Main spar web and doublers The main spar webs  come pre-drilled and rolled up. After they are unrolled and mated with all the doublers they can be clecoed together and the spar caps can be slipped into position. I began by doing this and laying out the various angles into place. These are all the W11 pieces that make the stiffener reinforcements.  I used the double-ended carpenter square method to set the spacing between top and bottom spar caps before clamping and drilling the spar caps, using the pre-drilled spar webs as a drilling guide.  In the first picture you can see the sandwich of the main spar web, the main spar aft web, and center web fastened together with the upper spar cap slid into the top. I spent a week in evenings dressing the spar caps and filing the leading edges of the spar cap outer angles until they were flush

 

   

Fitting the stiffeners onto the main spar. In a couple of the pictures, you can see the double square setup used to set the spar height. I circled the pilot holes with blue marker so I wouldn't lose track and drill them up for rivets. I used wd-40 to lube the drill bit for all the holes. It really helped in the spots where there was a lot of metal to go through like the web/spar cap holes. In the lower picture you can see where I was drilling up the holes for the driven rivets from 3/32 up to 1/8 and then to 5/32.

Riveting the main spar

After much reading and trepidation that I would screw something up, I started driving rivets. I used the Avery c-frame riveter/dimpler that Dave Harster was kind enough to lend me for the job. I practiced with the flush and button headed rivets for a while before I started on the real parts. Some of the practice ones I cut through the metal and rivet and it was reassuring to see how solid everything went together. I don't have any pictures of those practice pieces. Riveting worked best on the floor giving a solid base to hammer against. Three blows was usually sufficient to get a nice looking rivet. The last shot below was a "victory" shot which felt like a large milestone in progress. I spent roughly 2 months of evening work and probably 4-6 hours on 1/2 of the available weekend days

Joining the spars

After both main spars are complete it's necessary to join them together, aligning the reference holes to drill the mating wing attach blocks up to 1/4. You can see how both spars fit together in the middle in the close-up shot. I had to open the door to the shop to get the assembly to fit on top of the table.