I finished up the main parts of the rear spar tonight. First I deburred the inboard spar doublers. I hit the edges I could with the scotchbrite wheel -- always works great. Then there is the inside part that the scotchbrite wheel couldn't get to. I just picked up a used bench sander the other day, so I decided to put that bad boy to use. It worked perfectly. It really earned the $35 I payed for it this session. Next I match drilled the two doubler plates. The one on the tip was easy to do. The middle one around the aileron hole is a bit more difficult. Van's gives you a basic measurement, but you gotta make sure you have the proper rivet hole edge distance on the flanges that take a #40.
Next was drilling the aileron pushrod hole. I did it the recommended way of getting rid of most of the metal with 2-3 unibit holes. Then I broke out the file, then the dremel with the sanding wheel. When I got it close, I clecoed it back into the spar and finished it up there with files and emery cloth. Its a near perfect match - less than 1/64" off. I wasn't going to risk enlarging the hole in the spar to get any better.
Next was match drilling the inboard spar doubler plates. All that's left is deburring the holes, countersinking the dimpling...then of course priming.
Drilling the tip doubler.
Drilled the center doubler and marked where the aileron hole is on the doubler.
This is the hole you need to cut.
Both doubler marked.
I first clamped it to two 2x4 scraps.
Then I drilled 2 #30 pilot holes.
Then enlarged with the unibit.
I used my dewalt cordless drill because it is just so easy to swap bits.
This is after filing a little so there is enough room for the dremel sanding wheel.
I basically took the hole to the line with the dremel. I knew I had about 1/32" more to go after this.
This is my knock off sears dremel. Works great.
And the finished product.
Now back to the easy stuff. Match drilled the inboard doublers.
Last Modified: June 5, 2023