Stephan's Sonex #1627 Builder's Log

I finally riveted the left side of the veritcal stabilizer. I also attached the fiberglass tip.

I continued work on the rudder today. I made a hinge drilling jig (or guide) to help me drill the 41 holes that are required in the rudder hinge. I also cut the pre-formed rudder control stock to length and made the cut-out for the rudder control horn. I used a Dremmel Saw-Max with an aluminum oxide blade that cut the control stock as it if was butter. The cut-out was done initially with aviation snips and then with the Vixen file to clean it all up. 

The ribs were marked up with a centre line on all the flanges. I then marked up on the control stock and drilled the holes as per the plans. Once the holes were drilled in the stock, I put the rib inside of the control stock and used the holes to line up the rib with the centre line that I had drawn on it. I then drilled pilot holes in the ribs with 3/32" bit and cleco-ed everything together.

The rib at the top of the rudder had to be flush with the edge of the stock. I used a metal ruler to make sure that the rib was completely flush. I then drilled the holes and cleco-ed everything together.

It was getting late, so I did not complete the drilling of the control stock or the control horn. or installing the hinge.

The rudder drive horn assembly required a small part (-06) be made from angle stock. I initally clamped all the pieces together and used a metal ruler to make sure that all the flanges were aligned then drilled 3/32" pilot holes and cleco-ed everything together. I then up drilled everything to #30 and deburred and cleaned.

I wanted to experiment with Alumiprep and Alodine 1201 so I setup 3 baths, one with 25% solution of Alumiprep, another with a 33% solution of Alodine and finally a water bath for washing the parts. I scuffed the parts with some maroon Scotchbrite and then cleaned with alcohol and put it in the Alumiprep bath. I left it there for 3 minutes. There was still a significant amount of gas formation, which probably indicated that I had not done as thorough of a job removing the oxidization layer. 

After the Alumiprep bath, I thoroughly washed the parts and then put them in the Alodine bath. The alodine contains chromates, which are very hazardous to health, so I wore goggles, respirator and thick rubber cloves. I waited about 3 minutes and then turned the parts over for another 3 minutes. After this, the parts were washed thoroughly and blown dry with compressed air. The result was not too impressive. The parts did not appear to be uniformly anodized. There were dark spots and very light spots. It also appeared that I could easily remove the anodization by gently rubbing it with my rubber gloves.

I had already bought 4 cans of Sherwyn-Williams GBP 988 self etching primer, I'm going to use that instead on the next part.

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°.