With everything primed and ready to go it was time to start the final assembly for the HS. The plans have you start with the rear spar as it's probably the easiest part of this assembly stage. You use the spar doublers to join the two rear spar halves and rivet them together using AN470 rivets. These were the largest rivets I've used yet in terms of length. The plans call for AN470 4-6 rivets which are fairly long but once they are set through the doubler and the spar itself, the majority of that length is inside the structure so they are just the right length for this part of the build. I went round and round about which direction to place these rivets, then went round and round some more. I checked other build logs, surfed VAF, etc. Long story short, it doesn't really matter, sort of.... The general consensus is to place the factory/manufactured head against the thinner of two pieces of aluminum. In this case that would place the round head of the AN470 rivets on the front side of the spar (as installed on the airplane). To me that didn't make any sense since the round head has the umbrella shape to it and it would seem that it would tend to hold onto the doubler better than if I created a shop head on the doubler side. Squishing the opposite end of the rivet effectively fills in the empty space of the hole and the holding force is essentially equivalent to that of the factory head. In the end, even the Van's engineers will tell you that it doesn't matter which way you place them. It seems most builders eventually learn to place them in the orientation that make the most sense based on ease of access, riveting access, looks or even what will be easiest to drill out should that occur on the airplane some day down the road. Think about it, would you rather try to drill out the factory head side of a rivet or the side you squished (the shop head)? So with that in mind, I placed my rivets with the shop heads on the front side of the spar. In the end, it was a lot to do about nothing. There's as many ways to put these parts together as there are opinions on how to do it. Perfection is the enemy of progress and in this case I wasted a lot of time researching something that I really didn't need to. One last bit on rivet direction/orientation, there is some thought out there that the actual plans themselves (the drawings) indicate which way to place the rivet. Look at the pics below for a description on this theory.

So once the direction was decided it was a simple matter of setting all of these rivets thereby joining the two halves of the rear HS spar together. No going back now. And then it hit me...... WHOOPS! Forgot a step that I should have done BEFORE I started riveting the two halves together. The plans DO NOT mention this step at all, again a case of having to reference both the drawings AND the plans for things that must be accomplished. The DRAWINGS have you notch out the lower portion of the rear HS spar so that the elevator horns (later in the build) can make contact with their physical stop block. If you don't notch the spar out, the horns will hit the spar itself and not the designated stop block. You would limit your elevator travel doing this as well as damage the spar from repeated contact. So cuss word, I realized it almost right away. Goes back to the idea a planning out how you will tackle a certain part of an assembly so as not to miss crucial steps in the process. Again here's an example of where the plans leave you hanging so be careful. I decided to notch the piece out after I finished joining it together at a later stage.

I set all of the rivets with my hand squeezer ('Main Squeeze' from Cleveland Tool) as shown in the photo. Again these were the largest rivets I've tried to set with the hand squeezer to date and although it took a good amount of squeeze force to do it, it managed the task fairly easily. I tried the pneumatic squeezer on a few but I just prefer the control I get with the hand squeezer. I've learned to hand squeeze, then pneumatically squeeze and finally buck with a rivet gun, in that order of preference, for setting rivets. It's so easy to tip over a small rivet with a rivet gun, the hand squeezer by far produces the most reliable and repeatable results. With all of the rivets set joining the two doublers to the two halves of the rear HS spar, it was time to move on to the elevator hinge brackets.

BTW like everything we do, setting up the parts for ease of access is key, you see in the images how I have the spar clamped to the long board that supports it off each end of my work bench. Can't have enough clamps IMO. A big thing to watch for is to make sure you don't rivet certain holes as they get riveted later on in the sequence, again masking tape is your friend here and you see one of the images where I used small strips of painter's tape to cover the holes that were not to be riveted just yet, namely the holes for the elevator hinge brackets.

The brackets themselves were pretty straight forward with one exception. The rivet call out in the plans didn't seem correct on a few of them. The rivet was either too long or too short for the set. You can see when you place the rivet in the hole if it looks about the right length. On some it was clearly not the correct length (at least to my untrained eyes). So I got to experiment with my rivet cutter at this point. I cut a few off to a perfect length and a few I used the next longer sized rivet. So some of my hinges have different length rivets on the same hinge. I ended up getting the calipers out to measure the shop head after they had been squeezed. I wanted to know for sure if they were within tolerances for a driven rivet. Again here is an area of some debate. The rivet gauges I have are not always useful as they only show you if the rivet meets/does not meet a certain diameter once it's been set or a certain height once it's been set. There is actually a range of size for the shank once it's been set and the rivet gauges are right in the middle of that range (as they should be). So the set head may be slightly larger than the rivet gauge or slightly smaller than the rivet gauge and by the mil specs, it's still a properly set rivet diameter wise as well as height wise. Again a lot of consternation about a minor thing. Still learning as I go but I feel better knowing there is wiggle room on the size of the shop heads. As someone told me once, if you stress out over every single rivet on this project, you will never finish.

With all of the outboard brackets riveted in place, that just left the center hinge bracket, the HS-411, and as it's the big one, it gets bolted in place and the nuts torqued on so without a proper torque wrench to finish this step this was a good stopping point before I had to head back to work and off to Europe on a trip that would take a week.

Regarding the drawings and rivet directions. There are a few builders who say to look at the drawings and they tell or maybe recommend to you the order of the parts to be riveted together. In this last image look at the callout for the 609PP to the 603PP parts. The 603PP is the spar half and the 609PP is the doubler. Notice how the drawing says "AN470AD4-5 ALL HS-609PP TO HS-603PP RIVETS". What they're saying is that the plans tell you to rivet the 609PP part to the 603PP part thereby telling you to drive the rivet from the 609PP into the 603PP which is how I did it BTW. So round factory head on the 609PP doubler driven into the 603PP spar half. Whether that's a thing or not I don't know. Someone else said that's Van's giving you a recommendation on which way to place the rivet. Again open for debate but for the most part, this seems to make sense.