Priming Done, Riveting Started

It took me another day until I could get to prime the parts of Section 14. Work was crazy and the air still humid, so I didn't want to carve out day time to do this.
So today in the morning I started the priming and all went well. I also did not forget to stack up all prepped parts and weigh them before and after the priming. The stack of weighable parts (everything but the rear spars) came out at 1411 grams (yes, grams! I don't see why you should come up with fractions of an ounce when there is a unit that has a reasonable resolution to so the job).

All this came out at 1411 grams:



After two hours the parts looked like this and formerly weighed 1411 grams was now at 1436 grams, a difference of 25 grams ( yes, I waited a few hours to let the parts dry before weighing them) or 0.882 ounces or a little less than 23/256th of an ounce.



So, the weight increase was about 1.77%. While this is particular to the combination of these parts as the weight increase is certainly a function of surface area (which I was too lazy to calculate), on average this should be a reasonable number for basic parts that are not skins or ribs (as these have a low weight but a huge surface area).
If I would apply the 1.77% to the advertised empty weight of the finished product of 740lbs, I get 753lbs primed. I think I saw 755lbs reported on the Van's Airforce Forum for one that was completely primed on the inside. So, I assume this is a good figure for the estimate.

After the primer had fully dried, I started the fun part of this section and went on to assemble the hinges.



This is how they looked after priming. Now, I remembered from the early beginning in May when assembling the hinges for the rudder that the COM3-5 bearings are very sensitive to primer dust inside their milled seating area. So, I went ahead and scraped the inside of the hinge flanges clean of primer.



I also remembered to bent both flanges a bit towards the inside so they would open up and leaving an ugly gap when riveted.
Then I noticed that I haven't been riveting delicate parts like hinges for quite some time so I figured it'd be best to get some squeezing practice on something else that's not so unforgiving. The flaperon hinge brackets seemed to be a good candidate for that and sure enough it turned out to be a nice practice.



The I decided to increase the challenge a little by riveting the doublers onto the nose stub spar. This included riveting countersunk rivets in doubly countersunk holes in order to get both sides flush. I felt the suggested rivet AD3-3 was a bit too short to really provide enough area in contact once it was seated. I tried a 3.5 that sure enough was a bit too high when the squeezer applied all the force it could but it was filling the holes much better. I decided to use a punch and a sledge hammer to set rivet deeper and using the concrete floor of the workshop as an anvil turned out to be an excellent job. I used 3.5 rivets on the other spar doubler inboard are exclusively.



Oops, that was the pretty part. Here's the inside:



The primer suffered a bit but the surface across the rivet is now completely smooth AND the shop head fills the countersunk hole completely.

Well, finally that all left me with not enough to really start on the hinges but I at least clecoed them and fine adjusted them for proper alignment. It is probably a good idea anyway to start riveting a delicate part like in the morning...