Primed the F-711 Bulkhead and started assembly - 3.5 hours

Very small day today. I just need to prime the components before I can assemble them. I always try to get 12hrs dry time on the parts when I can as the primer can be too soft.24 hours is best. 

My priming process is a little intense. First a scotchbrite scrub, then soapy wash, then acid bath, Degrease wipe, MEK wipe and prime.

All done with priming. Now to wait for it to dry.

I waited until the late evening to start assembling. I cleco's the assembly and clamped it in the vice, and started bucking.

As I started the row at the very top (where it isn't clamped well). I slipped with the rivet set and gave the piece a small smiley. Ugh....very annoying. I managed to perform some surgery and dressed out the smiley with some scotchbrite on the dremmel to remove any sharp edges.

I then wiped the area with acetone and masked off the set rivets and re-sprayed primer. Almost like it never happened.

Prep'd the F-711 bulkhead components - 3 hours

I was ready to prep and prime the F-711 bulkhead components. Unfortunately this took quite some time as the F-711 bulkhead as a lot of little tabs, nooks and crannies. Like every other piece I broke the edges with a small file, and then polised the edges on the 3M wheel. All of the nooks and crannies get polished with the maroon scotchbrite on the dremmel tool.

Fabricated F-711D and fitted to bulkhead - 2.5 hours

Well, after getting back from holidays in Mexico the desire to build is very low. I have to make myself get into the garage today. I fabricated the F-711D angle which is fairly straight forward. I took my time and made sure it was exact. Once fabricated, I carefully clamped it to the Bulkhead.
 
 I drilled and clecoe'd. Yup everything looks good.

I set the angle so that the bottom of the flange is even with the top of the bulkhead as per the plans.

More work on the F-711C bars and the F-711 Bulkhead - 2 hours

I wrestled with the idea of cutting down the horizontal attach bars. Of course on the RV7 they are not cut down, but the plans call for it on the 7A. I see on some 7A build logs not everyone cuts them down and I suspect to maximize strength. In the end I decided to cut down them down to shape to save the weight. Everyone complains about the tail being heavy, nobody complains about this area being weak.

All cut, finished on both the sanding station and the 3M station.

Next, I went to work with the files on the F-711 bulkhead opening.

Working the F-711C bar (again) and working on the F-711 bulkhead - 3 hours

The replacement AB4-187x1 1/4 arrived so I can remake the F-711C horizontal stabilizer attach bar. Fortunately I have one completed and ready to go so it makes things very quick to so the second. I measured everything out. Placed the correct piece overtop and used the palm drill to provide pilot holes for the bottom most hole and top two attach holes. Before completing the holes in the drill press I verified the measurements of the holes.


Looking great, so I finished the holes in the drill press. Next I then cleco'd the attach bar to the F-711 bulkhead and transfer the holes. Then I completed those holes on the drill press.

Then I marked the space that is cut out on the F-711 bulkhead and cut it on the band saw.

I will have to finish these off with a file.

The longeron twist - 2 hours

No magic here. The twist goes extremely quick and is very easy to do. Looking at other blogs, I used a piece of 2x4 that I cut out the shape of the angle out of the wood. It was about 2' long and made the bend very easy.

First I verified that I was 0deg before the twist. 

I used the 2x4 to twist the angle. I must admit I checked about a hundred times to make sure that I was twisting the right way, the top of the angle bends in, and the bottom bends out. It only takes a few mins to get the 17deg bend.

So glad to be finished with the longerons. They got stored up in the garage for installation later.

The sharp downward bend - 3 hours

 I'm glad to be finished the big bend or curve as it was very nerve wracking. I was terrified of ruining the longeron, but in retrospect it wasn't that difficult. Just quite time consuming and a little frustrating as the plans suggest. An I too agree that its best done when broke into small segments.

Fortunately the sharp downward bend goes much quicker. I was careful not to put a sharp edge on the piece of oak that i'm using using for a bending block (its 1/8" radius) as I have found in the past bending aluminum around sharp corners can cause cracks at least with thin material....so why stop now.


I was having a tough time figuring out how best to set up for measurement of the 2 3/4" drop. I have a bike stand that I used to clamp a wood ruler onto.



It looks good in theory, but in actual fact it doesn't work so well. I ended up in the end just simply using the straight clamped across the top and using a ruler to measure the drop. The sharp bend down causes quite the bend in the other direction so ultimately the stand just gets in the way.
To promote a clean sharp bend at the 28 1/4" mark, I locked the angle down in the vice and clamps.


I began to bend, check, correct for straightness, bend some more, so on, and so on. I managed to get one finished fairly quickly. But it is time consuming to remove the clamps just to do the measurements. One all done...Measures 2 3/4" apart from the unbent one.

Now its 5 1/2" apart when both are bent, and more importantly both are perfectly aligned.

Best of all, it matches the skin perfectly.