Fabricating replacement Z brackets, aligning the rear baffles

The new Z brackets with the larger flanges finally arrived. I had actually ordered the wrong size brackets at first. The actual brackets have a height of 1 1/8" but I mistakenly ordered brackets with a height of 1" instead, so I had to order another set with the correct dimensions. The unfortunate thing about the larger brackets is that they only come with 1 1/8" wide flanges, meaning they have to be cut down quite a bit for this application. Not a huge deal; this is a custom installation after all.

The brackets actually come as a single piece of Z channel, so to start I cut each bracket to length. Next, I set about finding the exact middle of one side of each flange and drilling a hole to match up with the hole in the fuel tank baffle. The holes in the baffle are aligned perfectly, so that was the side I clecoed first before match drilling anything to the spar.

With the brackets clecoed in place I again used the largest bit I could to match drill the angle through the nutplates already installed on the spars. Finally, I took the brackets off of the spar and updrilled the bolt holes to #12.

The new brackets have much better edge distances for all of the holes. A quick check with the bolts revealed that there is plenty of room to bolt and unbolt this bracket easily. I had seen some builders have issues with being able to fit a socket around the head of the bolts since they were so close to the angle, so thankfully I won't have this issue.

Holding the original bracket next to the new bracket shows just how much more material there is on the new one.  

I cut off the excess aluminum with the bandsaw and deburred the edges with the scotchbrite wheel. The finished flanges only ended up being slightly larger than the original brackets, but these will work way better than the old ones. Done!

Now that all of the brackets were in place I could finally start to align the rear baffle with the holes in the brackets. As expected there were quite a few variations in where the holes fell. Read, most of the holes didn't line up at all. This was mainly due to my barely-adequate centering of the holes in the brackets when drilling them. The plans say to elongate any holes that don't match up, so these are easy fixes.

This was one of the worst offenders. Most had some slight misalignment, but this one required substantial elongating of the hole in the baffle to fit. Any more misalignment than than and I would have considered making a new bracket.

A couple ended up being perfect though!

The easiest way I found to elongate the holes was to use the #30 reamer. The drill bits aren't really designed for removing material via the side of the bit, but the reamer chews through these holes quickly.