Wednesday, July 6, 2016

Little more debur, countersink, and dimpling - 4.5 hours

I had finished the majority of deburing and counterskinking however there is just a handful of places where I just couldn't reach the end (inside) ribs where my wing stand structure blocks access. I've built a slightly smaller wing stand structure than indicated on the plans to maximize space in the garage. It works, but I have to make some concessions to make it work. ie. I have to climb under the structure to access between the wings. I will have to rivet the skin on the wing, with one wing at a time. And of course in today's work session, I have to take the wing structure off the stand to access a few locations. Not the most efficient setup, but given that I need the space in the garage, this is a totally workable situation.

So I had pulled the left wing off the stand and finished the 6 or so holes that needed to be countersunk, as well as the handful of holes that needed to be dimpled.

Now it was time to countersink the rear spar (top) holes. The bottom ones are very easy to do with the pneumatic squeezer. The top side is another story due to the angle and interference with the rear spar. I've been giving this area some thought for a while, and I figured that my vice grip 3/32" dimpler would do the trick. I tested a couple of holes first and checked with a rivet. The dimple is not as nice as the pneumatic squeezer, but it works.



Once I was complete I pulled out my microstop countersink (having it set up for the main spar I just did) and I started to check the holes. Of course the holes that are dimpled with the vice-grips take some material off. I then checked the bottom of the rear spar that was done with the pneumatic squeezer and little to no material is removed. I decided that this is the correct setting and went to work cleaning up the top side holes on the rear spar.

Next order of business is to clean an prime the spar where the countersink holes are made. The manual indicates that this can be done as a spot prime while countersinking (i.e. when doing the tank screw countersinks) buy I opted to prime the whole face as some builders choose to do. I masked off the front spar and primed it. I had also primed the top of the rear spar where the machine countersink had removed the primer (and where the dimpling operation flakes off the paint).


As I let the primer dry...I moved on to starting to de-vinyl the wing walk doubler. Next operation was to debur. Now at the back of my mind, I had to keep my dimpling operation correct. I had chose to dimple the ribs for the wing walk doubler with tank dimple dies. The idea is that if I dimple the ribs/doubler skin with tank dies, and then dimple the skins with regular dies this will provide slightly better nesting. However....months ago when I dimpled the rear spar....I didn't use this thinking and I dimpled with regular dies. Confusing I know but basically when it comes to the doubler the bottom line for my build was this;

Dimple the rear spar line with regular dies, dimple the rest with tank dies. So...to make sure I mitigate the risk of messing this up at a later date. I dimpled the rear line.
 
Of course it wasn't midnight yet and I was still wide awake...why not do a little more I thought. So whats a little more deburing and dimpling? I took the left leading edge out and debured. Now...most important for me to remember. I used the edge forming tool and ran through to two edges. Next I dimpled.

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