Drilled and Primed Bulkheads

Posted on by Neal

Today I spent a couple of hours drilling and dimpling the aft bulkheads, and then a couple more hours priming several parts.

I used the drill block to match drill several holes from one of the bulkheads into the Vertical Stabilizer, the block was a huge help to ensure these were perpendicular to the bulkhead web. I was happy with how they turned out. Three of the holes will get final drilled to #12 and will take bolts that hold the vertical stabilizer to the fuselage. Any error in the hole orientation will effect the aerodynamics of the VS.

I needed to dimple the flanges of two bulkheads, but due to the angle of the flange, there is no way to get a female die on the inboard side of the flange. I have a spare squeezer yoke, so I cut off the end with a hacksaw, then ground it down to a small cross section. With the modified yoke, I was able to squeeze the dimples.

Modified yoke for dimpling angles flanges
Modified yoke clears the bulkhead web and the female die sits flush with the inside of the flange

In the evening I primed several parts for the aft bulkheads. The new hi-flow connectors made a significant difference. I used less paint, and the finish was much better. The paint atomized into much finer particles, covering the parts more evenly. The compressor was working harder, and I had to wait for it to catch up a few times.

About to start priming the aft bulkheads

It’s hard to tell from the photos, but the finish is significantly improved.

Primed bulkhead. The finish is much improved with the hi-flow connectors

Primed elevator parts

Posted on by Neal

This afternoon I was able to get some time in the garage, thanks to visiting grandparents. I cleaned, etched and primed all of the elevator parts. I’m not planning to prime the skins, since I’m trying to save weight in the extreme aft part of the aircraft. The arm is so long at this point on the aircraft, any increase in weight has a disproportionately large impact on the center of gravity, bringing it further aft. Weight aside, priming the skins isn’t really essential. Every mating surface will still have at least one layer of primer, helping prevent any possible corrosion.

I started by using Stuart Systems EkoClean to clean all of the parts. The ribs were the most time consuming, with multiple flanges and other nooks and crannies. Then I etched all of the parts using Stuart Systems EkoEtch. I sprayed the larger parts with the hose to make sure the residue was removed, then set them out to dry. After dinner, the parts were mostly dry. I air blasted them to make sure the holes were clear of water, and then I mixed up the EkoPoxy primer and got started. I mixed up 200 grams of part A, which turned out to be more than I needed. I’ve gotten much more comfortable with my spray gun now, and was happy with the outcome. A fairly consistent light coating everywhere, with a few spots of slightly heavier coating. The white color is hard to see when being applied, so it’s hard to judge how evenly the coats are going on. I did two coats on everything, and focused on the surfaces that will mate with other parts.

Primed Horizontal Stabilizer parts

Posted on by Neal

Apart from the skin, I primed all the HS parts today. The process went a little faster and easier than before, and the results look good. I mixed 200 grams of part A, and used a little over half what I mixed up. It really doesn’t take much to coat the parts in a thin layer, and according to the manufacturer, a barely visible layer of this epoxy primer is 90% effective.

Here are some before and after pics. These parts are cleaned but not etched:

And here they are primed:

These parts are cleaned and etched:

And now primed

Primed Rudder Parts

Posted on by Neal

I primed all of the rudder components today, starting with cleaning, then etching, then priming. Because it takes a while, and parts of it are time sensitive, it’s easier to do on a weekend day than in the late evening during the week. The job was much easier the second time through, and I was really happy with the end result. I have a nice light but complete coating on all parts except the skins. I decided not to paint the skins, because every part that touches the skins will be primed. If I end up scratching the skins, I may prime parts of them later. I am clear to start construction of the rudder frame now.

With the painting done, I squeezed a couple more rivets in the Vertical Stabilizer. Unfortunately one ended up sitting a bit proud of the skin, so I had to drill it out. It turned out to be a real pain, but eventually I got it out, without enlarging the hole.

I going to have to buck the last remaining rivets in the back of the Vertical Stabilizer skin, as I just can’t get a squeezer in to a few spots due the universal head rivets that hold the doubler to the spar.

Priming Vertical Stabilizer

Posted on by Neal

I finally had some time back in the garage tonight after a few days away with the family, and waiting for some painting supplies to arrive. My dad helped me prime all the parts for the Vertical Stabilizer, which turned out to be a frustrating job. I’m using Stewart Systems EkoPoxy to prime, which seems like a great product. All of the frustration I ran into could be attributed to a lack of experience, since it was the first time I have used the products and equipment. The process involves three steps; cleaning, etching and then priming. Stewart offer three products to do this; EkoClean, EkoEtch and (in my case) EkoPoxy. EkoPoxy is a two part, non-toxic, water based, epoxy primer. The benefits are great adhesion, light weight, and easy clean-up. I used 100 grams of epoxy base, and just managed to cover the Vertical Stabilizer parts, including the inside of the skin. I was debating whether to paint the skin or not, and eventually decided I’d feel better knowing it was coated.

The cleaning process was easy, as was the etching. I used a maroon scotchbrite pad to manually and chemically etch the parts, then washed it off with warm water, then high pressure hose to blast off any remaining etch.

Then the priming began. We mixed up 100 grams of base (150 grams once hardener and water applied) paint and set up the spray gun. I’m using a 3M gun with 1.4mm nozzle. It took some time to set it up, first getting the right amount of pressure to the gun, then to adjust the fluid flow to get an even spay pattern. It was dark by the time I started painting, and found it hard to see how much paint was being applied due to the lighting situation in the garage. The white color was hard to see against the aluminum, and I ended up with an uneven first coat. A second coat improved matters, but then I found that the paint was sticking to the drop paper I was using. In a couple of spots I ended up with paper stuck to the part. Then to top it off I started to run out of paint before I could totally finish the second coat. I was intending to have a light coat, but I’m not sure if it’s too light. Will look at it again tomorrow in some better lighting, and figure out how to deal with the touching up where paper stuck to the paint.