Stephan's Sonex #1627 Builder's Log

I worked on polishing of the rear spar for the horizontal stabilizer and deburring of the spar channels. The rear spar had a lot of relatively deep cuts and stratches, presumably made while the spar was being fabricated. I used red Scotchbrite pads to smooth the surface and then used grey Scotchbrite pads to further polish it. I then cleaned with Paint Thinner and then sprayed with self-etching primer. I cleco-ed everything back together and riveted the whole rear spar assembly.

I worked on up-drilling the entire horizontal stabilizer and elevator assembly. 

I didn't get a chance to clean up my 8ft bench and remove the drill press and grinder that I had mounted to it, so I decided to work on the horizontal stablizer instead of the elevators. 

The first hour or so was spent making the main spar channel and forward spar channel parts from channel stock. Each end of the channel stock had a flange that needed to be bent either 90° or 22°. I used a wooden block that I cut to size that fit the channel and then tapered the block so that I could easily make the bend to 90° (which requires you to over bend it by about 5-10° - hence the tapering).

I rounded out the tip of the slanted end of the block so that I would have the proper bend radius. It turns out that wood may have compressed at the tip when I made the bend and I actually ended up with a bend angle that is much less than the 1.6mm bend radius that the plans call for. The parts with the 22° bend don't show any significant material compression near the bend, but the 90° parts hint of material compression at the bend.

I proceeded lining up the channels on the main spar and confirmed the overall length before drilling and cleco-ing everything in place. 

I worked on drilling the left elevator assembly today. I first drilled the pilot holes in the hinge itself and then fitted the ribs in place. I noticed that one of the rib's edges was taller than the other on the opposite side, and as I had always used the open edge of the rib as reference for marking up the centre line, this would cause a problem when trying to fit the rib. It would have likely required the rib to be twisted to line up with the holes I had drilled in the top and bottom of the elevator skins. Luckily, I noticed it in time and used the closed edge as a reference to determine the centre line instead. I have made a note to do this from now on. It will likely save me a lot of grief later on.

Once the ribs were in place, I removed the clecos from the bottom and laid the whole elevator assembly flat on the workbench. I then used my wood frame again to keep the elevator down while lining up the hinge. I again used a 0.060" spacer to line up the centre hole on the hinge and then worked my way outward to each side drilling and cleco-ing while alternating left and right. The drilling is a lot easier when there is a cleco in the adjacent hole, so I don't need to put a piece of wood behind it to prevent the skin from buckling while drilling.

Now that both the left and right elevators are done, the next step is to line them up and attach the control horn. This will require that I use my 8ft workbench.

I finally had a chance to work on the right elevator. I received the SNX-Z03-01 control stock a couple of weeks ago that I needed to redo the right elevator. Although the control stock is about $75 from Sonex, by the time it ends up on my door step, and shipping/handling/brokerage/taxes are added on, it turns out to cost over $250. Hard to believe for a piece of sheetmetal. I'm going to have to check the export documentation to make sure that Sonex is submitting the right paperwork and indicating the correct HS classification. Anyway, lesson learned: re-read the plans and check measurements before drilling!

I used the Dremmel Saw-Max again to make the initial cuts and then used the Vixen file and Scotch brite wheel to get me to the line. I marked the drill lines in the centre of the elevator and the edge and drilled the pilot holes. I made sure that all the holes lined up with the centre line on the ribs without requiring the ribs to be twisted, as this may warp the elevator once everything is riveted in place. Once the ribs were in place and one side cleco-ed, I laid the elevator flat on the bench and added a wood frame -made from 2x4s- to ensure that the elevator remained flush and not twisted while drilling the hinge. I used a piece of 0.060" aluminum as a spacer (the plans call for a 0.057" spacing, but I didn't have this available). I then lined up the appropriate hole on the hinge with the centre line on the elevator and drilled the first hole. I then worked me way out to each side, alternating left-and-right. After the hinge was all drilled and cleco-ed, I drilled the additional 6 holes in the ribs on the short edge of the elevator.

The next step is to work on the left elevator.

I worked on drilling the pilot holes for the ribs and hinge on the right elevator. This didn't go as smoothly as I had hoped. The top of the hinge had to be positioned 1.45mm (0.057") below the top of the elevator skin, but I had positioned it 1.45mm above it. The hinge is therefore positioned too high. This does not appear to be salvageable so I will have to order another piece of SNX-Z03-01 control stock and redo the whole right elevator. I have a feeling this won't be the last time I have to redo a part.