<November 21, 2007>
Crotch Strap Brackets - Day 3
Day 3 of the crotch strap brackets, although last night was so short I would hardly consider it worthy of counting it as day. Anyway, I was back at it today and I got the second bracket installed. As with anything in this project, the second time was somewhat easier. I refined my process a bit for the second one and I thing it went a little easier. I took lots of pictures, so please enjoy.
Before I started on the second bracket, I had one more task to complete on the first bracket and that was to drill the seat floor to the top flanges of the brackets. I clamped the flanges to the seat floor and first drilled them to #40, then I enlarged the holes to final size of #19.
Here is how it turned out. The edge distances are fine, but obviously a little off from the plans sent with the brackets simply because of the increased spacing required by the Hooker Harnesses.
Alright, onto the second bracket. I was pleased with the way the first bracket went, but I felt it could have been better. I changed the order of tasks on the second bracket and I think this new process worked a little better. Like the first brackets, the first task to complete was to mark the location of the brackets on the ribs. Like the first, I used the stiffening depression in the rib to draw a reference line.
Using my reference line to ensure vertical alignment, I then marked a line centered on the nutplate hole.
I then drew the lines for the brackets 7/32" forward and 3/32" aft of the line I had just drawn off the nutplate.
Here is where I started to change things up a bit. I clecoed the now marked ribs to the bulkhead and clecoed on the seat floor. I then slid the aft bracket into place between the ribs and loosely clamped it in proper position. I flipped the assembly over and verified the alignment of the top flange of the bracket, clamping it into position when I was satisfied that it was parallel to the edges of the hole in the seat floor. In other words, before I clamped the piece into its final position for drilling, I made sure that it was aligned with the hole in the seat floor. I hadn't done this on the first bracket, and the alignment while not bad, could have been better.
Next, using the wood spacer, I slid the forward bracket into position and clamped its top flange to the seat floor.
Here's what it looks like from the other side. Adjusting the alignment of the brackets relative to the seat floor caused me to make adjustments to where it was positioned, relative to the lines I had drawn on the rib. Clear as mud? If I had just blindly followed the lines I had drawn on the ribs, without verifying the alignment of the brackets to the hole in the floor, I might have ended up with a similar small misalignment that I did on the first bracket. As it turns out, the brackets needed to be installed about 1/32" further aft on one rib than the lines I had marked.
Now that I was happy with the position of the aft bracket relative to the hole in the floor, I drilled the top flange of the aft bracket only with a #40 drill using the holes in the floor as a guide. I then inserted clecoes into the holes I had just drilled to hold it in position while I performed the rest of the drilling for this bracket.
With the aft bracket firmly clamped and its top flange cleoced to the floor, I drilled the holes in the ribs using my angle drill.
With the aft bracket drilled and clecoed, I verified the location of the forward bracket using the wood spacer, and clamped it into position for drilling. Like the aft bracket, I first drilled the top flange with #40 using the seat floor as a guide.
With the top flange held in place with clecos, I double-checked the brackets alignment, and drilled the holes in the ribs with the angle drill.
With the ribs both drilled, I then enlarged the holes in the seat floor and top flanges of the bracket to #19.
I still have to drill the bolt holes in the brackets for attaching the harness, and I need to enlarge the hole in the seat floor so I can pass the buckle though it, but I am calling it quits for now.