I cut the seat belt fittings from 1 x 1 x 1/8" 2024-T3 Angle. I cut the pieces to length using my miter saw with a metal blade. This must be done cautiously but it works great! I then drilled the holes on my mill and finished the shapes on the disk sander using the seat belt hole as a pivot, Worked great! I then put them in my tumbler for awhile to debur. The seat belt fittings will get alodine finish at some point.
I then milled a small drill fixture to pre-drill the holes for the seat belt fittings into the triangular doublers. The block is held flush to he inner flat surface of the longeron and guides the drill bit perpendicular with a goal of coming out the opposite sharp edge of the doubler. I used 1/8 bit to drill these holes. The jig worked great and the holes were well located on the outer sharp edge of the doubler, definatley worth the effort. For the forward locations I was having trouble reading the plans dimensions, either 5 or 6 inches. I ultimately decided it was a 6 after some careful handwritting analysis.
Seat Belt Fittings - One Extra
Drill block and bit
Located in position and secured with hot melt glue
