Now its time to match drill the end fittings to the struts. Since the fittings are pre-drilled, we must clamp them to the outside of the strut and then drill through the existing holes and into one side of the strut. Once those holes are drilled, we will slide the strut fittings in place inside the strut and finish the hole all the way through.
Here is how to do it:
First double check that your wings are set up with 1 degree of dihedral and that the fuselage is level side-to-side.
The struts will be angled forward at the bottom because the strut mount on the fuselage is forward of the wing spar about 6" or so. This causes the strut to angle forward a little. Therefore, the top strut fitting (at the wing) must be mounted to the wing and tightened down, and then the struts are clamped in place. This sets up the correct angles and you can then match drill the ends to the struts.
Looking inside your struts you will see flat pads about 2' aft of the leading edge. your strut fittings must end up on the pads.
In preparation, for this procedure, take a Sharpie marker and transfer the edges of the flat pads inside your struts to the outside. Do this at both ends and on both sides of the strut. Make your lines at least 5" long. Now draw a third line exactly 2 1/8" back from the leading edge of the strut. This line should come out just about centered between the two pad lines you just drew. These are your reference lines so that you will know where the pad edges are and where the centerline of the pad is. Again do this on both ends on both sides of your struts.
Bolt your top strut fittings (they mount between the two bars sticking out of the wing) in place with 3/8" bolts and nuts. Snug them down but allow them to be able to pivot up and down a little.
For the bottom fittings, since they will be mounted straight along the centerline of the strut pads, you can go ahead and match drill them the struts on your workbench. Position the bottom fitting on the outside of the strut with the pad centerline that you drew, centered in the holes. Look inside the holes with a flashlight and make sure the line is visible and centered in the holes. Position the end fitting to stick out past the end of the strut 1 1/2" to the center of the 3/8" mounting hole as shown in the drawings. To allow you to tightly clamp it in place, you can slide a short piece of 1 1/2" thick wood inside the strut. Clamp it in place so it can't move and recheck that the holes are stilled on center along your pad centerline, and that 3/8" mounting hole of the fitting is 1 1/2" from the strut end.
Now using a 1/4" bit, match drill the first hole going only through one side
of the strut (not all the way through to the other side).and then slide in
a bolt. Re-check that nothing has moved and drill the 4th hole, slip
in a bolt. Now drill the middle two holes. Again, don't go all the
way through the strut to the other side yet. Only drill through one
side of it for now.
Now bolt the bottom fitting to the outside of the strut using washers and
nuts. You can then install the strut to the bottom fuselage mount and
bolt it in place with a 3/8" bolt and
nut:
The bolts I had were too long so I had to stack a bunch of washers up
so I could tighten it down all the way.
The top end fitting should already be installed on the wing. Position
the strut up against the top strut fitting and lightly clamp it in place.
As I said previously, this fitting will be angled slightly due to the way
the bottom mount on the fuselage is forward of the wing spar. The goal
here is to make sure that the fitting is centered on the pad as much as possible.
The two center holes on your strut fitting should end up being fairly
close to the pad centerline. The outer holes will be on either side
of the center line about 1/2 of a hole off center.
Again, to allow you to tightly clamp it in place, you can slide a short piece of 1 1/2" thick wood inside the strut before installing it. Once you are happy with the positioning of the fitting, clamp it down tightly so it can't move. Use a sharp, fine point marker and trace around the fitting so you will be able to see it if it moves.
Now very carefully remove the 3/8" bolts at the top and bottom strut mounts
and move your strut ,with fittings in place, to the workbench. Make sure
that the fitting didn't move any before drilling. As a precaution,
you can always drill the first hole, slip min a bolt and then test fit the
strut back on the airplane to make sure that it still fits well . Then remove
it and drill the other holes. As you drill the holes, slip a bolt in each
hole before moving on to the next. Again, down't drill all the way
through both sides of the strut, just one for now.
Now with all the holes drilled through one side of the strut, your can remove
the strut fittings and debur the holes in the strut. Now slide the fittings
inside the strut and slide in a couple of bolts to line it up with the holes
you drilled. You can then finish drill your struts all the way through the
other side, sliding a bolt in each hole as you go.
Sorry for the blurry picture.
Disassemble, debur all the holes and then reassemble with bolts, washers
and nuts, torquing them down to the proper specs. Repeat with the other spar
and you are done. Mount your spars on the airplane, remove the "T"
braces and admire your work!
This thing is starting to resemble an airplane!
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