Spar Box on the Way

This evening I was able to get quite a bit done. I washed off the rough surfaces of the parts I primed yesterday with water and a hint of soap and a Scotch pad (not a scruffing one but the one for doing the dishes). It might be due to the heat and dryness in Tucson but even with diluted primer (you can add up to 10% water to VpCI-373) it dries so quickly during spraying that the surfaces always end up being quite rough after they completely dried. I tried a few things to polish it afterwards and what works best and quickest is that aforementioned Scotch pad for dishes and some water. Afterwards I rinse it quickly with water and let it dry.
After the washing I could already rivet the inner Spar Box. Nothing exciting here, except that the plans are very wrong about the rivets to use. That includes the Where and also the type. The noted AN426AD3-x are not marked everywhere where you should put them to finish the inner Spar Box. That's not too unusual for the Oregonian Manuals as we've already learned in the previous sections but this time they call out AD3-4 rivets in places where they appear to be too long and the AD3-3.5 are totally sufficient. Use the -4's only on the far out countersunk holes on each far end of the Box. It's obvious that you need the longer ones there as you have to rivet 3 pieces together. In the inner locations though my gauge shows that the -4 are too long and not necessary.
Besides that there were no further surprises - except that I had previously forgotten to deburr the outer spars that would complete the Spar Box Assembly. So I had to do that and then ran out of time before it was time to close shop and head for bed. That's why you can see the Main Spar leaning next to the rest of the Box.