Making Ribs

I mounted the aluminum angle brackets on the right wing and started making the ribs this weekend.  I decided to primer the brackets like I did for the other spar pieces.  I am not going to primer the ribs.

For making the ribs, I followed the 6 part video series on the EAA website for making aluminum ribs.  

Here is a shot down the right spar with the half inch holes now drilled too.  

Here is a closeup of a leading edge rib bracket made from 3/4" .062 aluminum with AN3-6A bolts (The bolt size varies depending on the location along the spar) holding it in place.  I had to do some digging, but was able to find that the AN4 bolts should be torqued to 50-70 inch lbs of force (notice that is inch lbs and not foot lbs.  Big difference!).  There is a really great write up here that I printed for future reference in the shop.

I didn't take a lot of pictures of the rib forming process since I'm basically following the EAA video.  In the far background you can see my rib forming blocks.  One thing to keep in mind is to mark the fluting positions on your ribs.  You need to do that so your rivets fall in between them when you attach the skins.  

I'm fluting my ribs with this tool. It works fine.  I kind of wish it made smaller flutes though.

To flange the lightening holes, I'm using the process described by Dave Thatcher in the build manual.  It doesn't require an expensive die and is easily duplicated if needed.  You just use the fly cutter that cuts the lightening holes in aluminum.  You cut halfway from one side of the block, then flip it over and cut halfway from the other side.  You end up with a die like the one below that you place into the forming block to force the flange.  I've been using a hammer, but I might try the arbor press I used for riveting next.