2004-09-18


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Today I will start by bending the HS-702 spars to the same 6° angle as the HS-710 and HS-714 reinforcement angles. (BTW, the reason that I am always repeating the part numbers is not to be redundant, I believe that it will help searching the site later. All you need to do is enter the part number on the search page and find all the pages that I've worked on that part.) I started by re-locating the bend line which was removed when I polished the spar with the scotchbrite wheel. 
Then I clamped a block of wood underneath the spar so that the edge of the wood was directly on the bend line. You can't really see that in this picture. 
The I used the hand seamer to bend the spar right on the bend line. I over-bent it a little both times by about 3-4 degrees but it came back with hardly any effort at all. 
Here it is all clecoed back together.
I love the smell of aluminum in the morning...

(update 11/18/2004) when you get to this step, make sure that you have the correct HS-710. There were a number of empennage kits that went out with the wrong part here. Jim Diehl was kind enough to send me this picture of an INCORRECT Part which, unfortunately for him, came in his kit. 
Next, you have to countersink the reinforcement angles as shown on the plans. I start by circling the holes that need countersinking so I don't mess it up.
Then I use the Micro-stop countersink in the drill press. You don't have to countersink too much. After you do, put a AN426AD4 rivet in it and see if it's flush.
Nicely countersunk...
I need to start thinking about priming these parts. Unfortunately the spray gun that I ordered from Harbor Freight isn't here yet. I ordered it on the 7th and here it is 11 days later. I checked the website and it hasn't even shipped yet. In the meantime, I want to go over to Irv's house and spray them with his gun.

This is the metal prep I got from Aircraft Spruce. It says to dilute it with two parts water to one part metal prep. 
I found this spray bottle that has markings on it to help you mix a concentrate with water. This sucker is PERFECT for what I want. It was up in the cupboard over the refrigerator for about 7 years. You can get one just like it from Amway. It only costs $14,000 and you have to sit thru 310 meetings and agree to waste all of your extra time eliminating your friends one by one by taking strangers into their homes and forcing them to buy toilet paper from you for $11 per roll.  Sorry to say, been there, done that.
The next step is to trim HS-404 to fit around HS-710 & HS-714. To do this, first I measured the distance from the edge of the flange. One side is 23/32 and the other is 31/32. Remember to make a left and a right. It's a little tough to see in this picture, but I have written a small L on this rib and an R on the other. 
Then I drew a line that was where I wanted to back-cut the part. 
Then I center punched 1/8 inch away from these two lines and drilled a 1/8" starter hole. 
The idea is to use the step drill to enlarge these holes until they become tangent with the two lines. Since the center was 1/8" away from each line, the hole gets enlarged to 1/4"D.
the step drill is very easy to use. especially if you run it in a drill press.
Then you take the snips and cut the flange along your line to the tangent point of the 1/4" hole.
Then, using the hand seamer, straighten out the two tabs from the flange so that you can cut the other direction.
If you never knew why you needed left and right snips before, you'll know after you build one of these planes.
All cut, ready for clean-up.
It is very important to get rid of all burrs and stuff from these cut edges. I use a fine rat-tail file to clean up the inside of the corners. If you don't clean these up so that they are completely smooth to the touch, cracks could form.
After cleaning up. This part was filed, and then buffed with the scotchbrite wheel.
Next the instructions say "Prepare" HS-404, HS-405, HS-706, HS-707 and HS-708. I'm going to go and figure out exactly what that means. I'm assuming that they mean to deburr, smooth and flute. We'll see.