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| Looks like some kind of eldritch-horror tentacle monster emerging. |
Oil is definitely needed here. Without it the drill bit is quick to bite into the lead and pull the drill down rather than pulling the material up and out of the hole. I would drill maybe a quarter of the way before having to re-lube the hole and the bit.
A couple notes for this step:
1) Make sure the drill is actually perpendicular to the assembly during drilling. The underlying E-703 and E-704 ribs are getting match drilled along with the counterweights, so if the drill is held at even a slight angle then the resulting hole in the ribs may be off center. Worst case, the hole ends up too close to the web or to the edge and both the rib and the counterweight need to be replaced.
2) Remove the blue vinyl immediately after the drilling is complete or the oil will probably be trapped under it. I didn't remove the vinyl until a few days later and the skin ended up slightly discolored around the drilled holes. If left on for too long this could probably cause some corrosion.
The second task of the day was starting to bend the aft edge of the right elevator skin. I followed the plans and made a bending tool out of some 2x8s and door hinges, with a scrap 2x4 put in the middle to gain some leverage.
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| The right elevator has the longest folded trailing edge in the build at around 5 feet, so I made sure to make the bender long enough to accommodate it. I should be able to fit the entire edge of any parts that need to be bent from this point on. |
Also at the behest of the plans, I went ahead and used some oak and steel welding wire to make a smaller bending tool for fine adjustments later on.
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| The edges are sanded smooth enough to prevent any creases in the skin when pressure is applied. |
I put the right elevator skin into the bender and made sure it was butted up against the hinges as closely as possible, then started the bend. Holding the skin in place is crucial to prevent it from slipping out of the bender; the skin slipping out of place during the bend causes the bend to occur well forward of the trailing edge and the skin becomes ballooned rather than folded.
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| Not bad! |
Just like rolling the leading edge of the rudder skin, it takes a lot more force to get the skin to bend than I was initially comfortable with. It's still good to take it easy at first to get the bend started, then increase the pressure as the skin gets more folded. By the end of it I pretty much needed to make the stiffeners touch the opposite side of the skin to get the bend to where it needs to be. The skin is bent enough when you can insert the spar, hold down the skin against it, and there's little to no springback when the skin is released.
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| No springback, and the skin rests almost completely on the spar. Success! |
I've seen some builders insert dowel rods into the fold to make sure the edge stays straight. This isn't really necessary as long as the bending tool itself is straight and you're holding the skin tight against the hinges on the bender itself. Not to mention, I've seen builders that have used dowels that slip out of place during the bend (completely negating any benefits of the dowel) or cause the bend to not be sharp enough (the dowel prevents the skin from bending far enough at the inside of the trailing edge). I ended up with a perfectly straight fold without using any dowels at all.
