Tonight's goal was to put a couple of hours on the plane without having to think too much...  For my fuel tank cap, I went with Van's deluxe locking fuel cap.  These fuel caps are very nice (and spendy).  These use a different filler flange than Van's stock fuel caps that are shipped with the wing kit so these deluxe caps have to be installed at the time of tank construction.

Because they are lockable, the fuel cap is oriented in definite locations (it can be locked down every 90 degrees).  So the idea here was to get the cap centered in Van's pre-punched hole and to have it oriented so that the latch is pointing straight aft (or forward) and not at some screwball odd angle.  The filler flange is angled so that it follows the curvature of the tank.  So orienting the flange is not to difficult.  If you are rotated out of position a couple of degrees, you can tell as it doesn't feel like it fits correctly up against the skin.

It should be noted at this stage, my fuel tank is clecoed together, but I have removed the inboard rib (T-703) so that I could use some simple clamps to hold the flange in place until I got a couple of holes with clecoes in them.

Below, is a far off shot showing the alignment of the fuel cap position .  I even had Tami come out if do some quality control for alignment in case my eyes were on crooked today.  To double check our eyeballs, I took a straight edge and ran it centerline from the forward to aft rivet holes and verified that the straight edge intersected the center of the latch rod and the little finger lip on the latch.

I just took it slow, drilled a hole, clecoed it, and made sure the hole I drilled was in the center of the fuel filler flange.  Went to the next hole (180 degrees out) did the same thing.  As I added clecoes, I took off my other clamps.  So far so good.

If you look at the filler flange, you can see the notches in the flange every 90 degrees.

After I got all the all the holes drilled, I inserted the fuel cap to make sure that the tank skin didn't interfere with the cap.  In the picture, it looks like it is not perfectly centered.  It must be the angle I shot these pictures because when I was putzing with this, it was perfect (thank goodness).  In the picture, the fuel cap is unlatched and you can see the keyhole.  Van's has put a little forethought when shipping these locking caps as they sent me two that were keyed alike.  Yes, you have to buy them individually.

Pictured below, you see the cap is latched and the latch is bent down (in-flight mode>>>   SOMEDAY).

While I was at it, I decided to countersink the fuel filler flange holes.  I made a test coupon out of some scrap aluminum.  However, for this coupon, I used my tank dimple dies (CAT Part #: DIE4263T) as I wanted a slightly deeper countersink to account for use of tank sealant.  The tank dimple die is supposedely .001" or .002" deeper than the standard 3/32" dimple die.

I don't particularly like countersinking as I have a difficult time getting consistent results with microstops.  Tonight, all holes looked really good...  I couldn't be happier.

Just a little anatomy lesson on these locking fuel caps.

Do I really need to go into more detail here???

I had a little time left before I wanted to quit for the night so I decided to cut out the tank access plate.  The first thing I was challenged to do was to determine the center of the hole being cut.  I tried to apply a little Geometry 101 here.  What I did was take two measurements 90 degrees apart with a machinists ruler.  I fixed one end of the ruler (with my finger) and then pivoted the opposite end.  At the maximum diameter, the ruler would intersect the center of the circle.  Do that again displaced by 90 degrees and viola, you have the center of the circle.

Okay, the center of the cutout has been determined...  Next, I had to adjust the cutter radius to get the proper diameter cutout.  I measured the INTERNAL diameter of the T-407 reinforcement ring.  Van's gives you the external diameter of the ring and you could subtract to get the internal diameter, but my way was just as easy.

After about 30 seconds of shaking the table with a spinning circle cutter, the damage has been done.  I deburred and took 400 grit wet/dry sandpaper to finish the edge of the hole.  It turned out GREAT....  WooHooo!!!!