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Empennage

Riveting HS day 2 … and drilling my first rivets out

I reckon there is a vortex hidden somewhere in my shed that disrupts the space-time continuum. It’s the only thing that explains how the hours just fly by when I’m in there. Had a BIG build session last night. I was starting to think about packing up when I looked at my phone … 02:00. “The 06:00 wake up call from the kids is gonna be fun” I thought to myself.

I had it in mind that tonight I was going to put the HS together. I had to sort out my forward spar clash and thought I might be able to juggle things around a bit to resolve this issue. Unfortunately, as soon as I put all the clecoes in the clash kept coming back.

There was nothing else I could think of other than to sand one of the edges back and provide more clearance. I used the sanding disc on my linisher to keep a straight edge and sanded a touch off the end. Then I broke the edges on the newly sanded section using my mini-files and checked for fit. It still wasn’t sitting quite flat even with some clearance between the spar channels. It appeared my countersinks were too small. Using very small adjustments, I ended up countersinking the relevant holes to be much bigger. They now were of a size similar to the ones Alex (the builder who popped in the other day) had on his angles.

I then checked for fit and it was much better.

I then removed these parts, taped up around the newly sanded/countersunk areas and sprayed it with self-etching primer. It ruins my nice green finish but I want the corrosion protection. I won’t be able to see this area unless the fairings are off so no big deal.


I then clecoed everything back together and essentially was back at the same point I was when I started an hour ago. /sigh

Using my pneumatic squeezer I set the rivets joining the forward spar channels and the angles. It was a little tricky squeezing the rivets in the centre due to some tight clearances with the yoke, but with a bit of playing around I managed to get them all squeezed.

Be careful with the rivets here. A couple of the holes don’t get rivets yet and a couple get flush rivets. The more observant reader would have noticed in the photo my mistake already. I then went to the next step in the plans which called for the inner ribs and nose ribs to be riveted to the forward spar and angles. You know…in those four holes you just squeezed rivets into. Oops. Looks like I got a bit overzealous and put rivets in the holes where the ribs join. Time to figure out how to drill out rivets. It was going to happen eventually, may as well happen now.

Step 1 – Centre punch the middle of the factory head

Step 2 – Drill out the core of the rivet using a drill with a smaller diameter than the rivet, and the hole it sits in.

Step 3 – Using a with drill the same diameter as the hole the rivet is sitting in, enlarge the hole you just drilled but only deep enough so that the bottom of the enlarged hole is roughly the same level as the skin. You Don’t want to drill through the skin so be careful. Sorry, no photo.

Step 4 – Insert a punch into the hole and snap off the head of the rivet.

Step 5 – Place a punch over the body of the rivet that is still inside the hole and then whack it out using a hammer.

I removed all 4 offending rivets and placed the main ribs and nose ribs into position. I found the nose ribs were clashing with the angles and just wouldn’t fit. Oh man. Here I was thinking I’d have the skins on by now and I’m still mucking around with the forward spar. I chanted to myself “I will not let the kit beat me”, so off to the linisher I went and sanded the problem notches. I broke the edges with my mini-file then checked for fit. All good.

I taped off the area around the sanded areas and sprayed them with self-etching primer.

I then clecoed the ribs to the forward spar and squeezed the rivets. There are a couple of different rivets called out in the plans due to the different quantities of skins being held together.



The plans then called for the centre nose ribs to have their top flanges riveted to the skins so I celcoed them into position.

Then I set the rivets using my rivet gun with flush rivet set and my small bucking bar. I didn’t quite push down hard enough on one of the rivets so it was sitting proud of the skin.

I drilled this offending rivet out and set a new one. This time it was nice and flush. The next step was to cleco on the tip ribs and the centre main rib. This was tricky. After trying and failing a few times I found that the least painful way (it’s not easy) to get the holes to line up to accept a cleco was to have the trailing edge overhanging the edge of the bench, get down on your knees, pull the skin down and try to push the top skin forward and pull the bottom skin aft. Easy to do with a bit of force when using two hands. One hell of a frustrating job trying to do this with one hand whilst holding cleco pliers in the other. It was fiddly and frustrating but in the end, do-able.

I then riveted the other side of the nose ribs. It was tricky trying to set the forward most rivet. I had to lay the bucking bar on its side and buck against its non-machined surface. The torch function on my iPhone proved invaluable in getting visibility in this region. I only had 1 more proud rivet whilst doing both nose ribs. I drilled that out and set a new one without too many problems.

I then inserted the forward spar assembly and clecoed the skins to the forward spar and the centre ribs.

Finally! It’s starting to look like a horizontal stabiliser. This is the stage I wanted to get to tonight. It took a little longer than anticipated but I’m stubborn so I kept at it until I got to where I wanted to be.

Build time 5.5 hrs.

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About gstrack

Husband and father of 2. Control & Instrumentation Engineer. Flying nut. Gadget geek.

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