I collected my main spar center section spacers from the engineering shop this afternoon. These spacers go in between the forward and aft main center section spars as shown in the pictures to simulate the wing spars during construction of the fuselage. I've made mine long enough to be used to man-handle the fuselage around with once it is together, and to be able to use them as hardpoints if I choose to mount some supports to them during fuselage construction.
To fit them I clamped them in position, made sure they were all level and then marked through the 1/4" holes in the center section to get the hole positions. Then I took them off, drilled clearance holes using my drill press, and then bloted the spacer back in using the 1/4" close tolerance bolts as instructed. I did this for each of the four spacers, and I'm rather happy with the way things have worked out.
