I decided to finish up the elevators this weekend. I updrilled all of the holes to final size and also cleaned up the overlap on the elevator root assembly. I had cut the elevator skins according to the size and angles required, but the control horn assembly that was provided by Sonex caused the skins to overlap by almost 5-7mm, with the overlap being more pronounced near the tips. I filed down the excess so that the elevator skins were flush with the edge of the root assembly ribs.
All that remains now is to debur, polish and prime the ribs and to rivet the bottom portion of the elevator. The top portion will have to remain cleco-ed until the MD-RA inspection is complete.
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.
The pre-formed parts from Sonex are nice, but they are not perfect. One side is taller than the other. You need to always measure the centre line from the closed edge of the part.
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.
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.
I got tied up with a project for work so I didn't get as much building time in over the past few weeks. Thankfully, the project is wrapping up so I will be able to spend more time in the coming weeks.
I worked on the cutting the left and right elevators to size. I've started using a wood-working iron to cut the plastic protective covering. I had been using a utility knife, but it always left some scratches on the metal skin which then have to be polished back out later. The iron worked well and gave nice and clean cuts of the material without any scratches.
I started by marking up the skins with all the cut lines. I used the finished elevator root assembly to confirm the orientation before cutting. It's easy to make a mistake here and make the angled cut in the wrong direction. I used the Dremel Saw-Max to make the initial cut. It worked reasonably well, but it does seem to heat up the material quite a bit, as the protective covering turned brown close to the cut line. I used a Scotch-brite wheel to take most of the excess material off and then used a vixen file to get me to the cut line.
Next, I will have to mark and drill the pilot holes for the end ribs, center ribs and root assembly.
I had some time during lunch today to rivet the elevator root assembly. I figured it was going to be easy and take me only about 15 minutes. Well, it took me the better part of 1.5 hours. It all went well until I couldn't get my pneumatic riveter perpendicular to the part to set the rivet because of the welded parts being in the way. I foolishly tried to pull a rivet with the head of the rivet gun on a slight angle. The rivet set with one side noticeably up instead of flush with the part. I decided that I was going to use the hand riveter for the other two adjacent rivets instead. I had practiced on a scrap piece before and believed that I could pull a good rivet. Well, the hand pulled rivets were even worse. I obviously need more practice.
I ended up drilling out the 3 bad rivets. I had to use a wrench to prevent the rivet head from spinning, but in the process, I created bite marks in the part from the jaws of the wrench. I now had to spend time polishing the scratches and straighten the flanges. I decided that I was going to try and use the pneumatic riveter again, as this seems to pull better rivets.
I decided to grind down the tip of the rivet gun so that half of the tip had a slight angle. This allowed me to put the proper force on the rivet head so that it remained flush with the part while pulling the rivet. This worked well for the first rivet, but I had to put a slight bend in the mandral of the other two rivets in order to ensure that the rivet stayed flush with the part.
I kept the same pressure (about 45 psi) as I was using before, but it took a little longer before the head snapped off. The end results looks fine. Lots of lessons learned today.
The 3 rivets that were replaced.
Finally got one side done, after replacing the 3 bad rivets.
The elevator root assembly was fairly straight forward. The only important thing to note was that the top edges of the left & right root ribs were not twisted.
One side drilled and cleco-ed.
Up-drilled to #30
Other side up-drilled and cleco-ed.
I deburred the ribs and horn assembly, then cleaned the ribs with maroon Scotchbrite and alchol then used Sherwin-Williams GBP 988 self-etching primer. I also used primer on the horn assembly, as the updrilling with #30 exposed bare metal. The final result is a lot cleaner and more uniform and consistent than the Alodine experiment.
After bending the forward spar fitting, I moved on to bending the drive horn. The same dowel method was used, but this time I was able to use the big vice, which made it easy. I got close with the vice and then used a rubber mallet to get me to exactly 5°.
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