393.5 hours on the hobbs - Countersinking the elevator rear spar

So yesterday I continued with dimpling the elevator skin adn the E702 front spar. I then hung the top flange of the E606PP rear spar over the edge of my particle board drilling board, and match drilled #40 holes through the existing holes in the spar into the particle board. Then I clecoed the spar to the particle board in every other hole so I could use my microstop countersink with the number 40 countersink bit to countersink all of the holes on the top flange. Worked pretty good.

I still don't like the inconsistent countersink results that I seem to get with this tool. Some holes end up a little more countersunk than others - not sure if it is due to an incorrect angle of the bit in the hole, too much pressure while drilling, or holding it on the hole for too long. Probably a combination of all three. Anyway, they came out acceptable enough for me. The trick is to countersink them just a bit further than the point where the flush head of the rivet is exactly flush with the top of the skin. You take it just a bit deeper to allow room for the dimple to sit down completely inside the countersunk hole. This then also allows the dimpled skin or part to sit flush on top of the countersunk part, making a strong joint in the process.

Here is a shot with several holes already countersunk. I placed a rivet in each one to check the depth. On other note about this. You need to do one of two things when you set out to use the countersink tool:
1. Make a test piece and check the countersunk depth on the test piece before doing it on the actual part, or
2. Start out with the countersink tool set to a depth that you know is much much too small so that there is no way you will remove too much material when you start out. Then adjust the depth of the tool until you get it where you want it.

Either method will work, and will keep you from damaging the part by drilling too deeply.

And a little closer shot to show how each head is just a bit deeper than flush with the top of the skin:

And the end result - both the top and bottom flanges of the rear spar sit nicely against the top and bottom of the elevator skin.

Tonight I would have finished dimpling a few areas in the elevator skin that require the close quarters tool or the C frame, and may have even finished countersinking the forward spar of the trim tab, but with the weather down to 5 degrees I decided to stay indoors tonight and get some non-airplane stuff done that I had been putting off long enough.Even if I get all the prep work done I still have to wait until the weather gets warm enough to prime the parts. My little radiator heater just can't keep up with temps that low, and I don't want to take a chance on screwing up anything on this part of the build because I was shivering from the cold.

Hopefully I will finish the remaining prep work and the riblets this weekend. There are two more weather systems waiting to hit us here in Denver over the next two to three days, so it may be next week before I can prime everything and start final assembly.

On another note, I have finally purchased my builders insurance policy. too much invested in everything at this point not to protect it.