I first printed the CNC pattern as a line output on 13x19 paper. I hand cut the pattern and folded it to check initial fit. I made some final adjustments for fit and retested, then I cut the battery box flat pattern from 0.020" aluminum sheet stock from the big-box store to practice bending and check final fit. I then cut the battery box flat pattern from 0.032" 6061-T6 sheet stock on the CNC. Triangular design cut outs were to provide some lightening of the box.
I cut all hinges for the three sides being secured to the firewall, plus the hinges for the battery retaining strap that will secure the battery in the box. Drilled all hinge #40 pilot holes at 1 inch spacing, centered on hinge lugs.
I started bending the 0.032" final box flat pattern on the bending brake. I forgot the important specification of bending the top opening 180 degree 1/2" lips to a 1/16" radius. This was not as important on the 0.020" sheet material. but was very important on the 0.032" final material. By the time I figured out how to get the lips bent to 180 degrees, I had bent them at entirely too severe of a bend radius. I destroyed the bending radius by flattening the lips using the brake alone, without any form of spacers, to bend the lips the second 90 degrees. I then just evenly flattened the lip bend radius. This ultimately stressed the bend so severely that after a small amount of handling the box to complete the other bends (the bottom and two sides), the lips cracked and began separating at the bend.
I completed bending the box to better familiarize myself with the brake. At this point it was a throw-away, so I got some practice with it.
I cut a second flat pattern to correct the 180 degree lip bends on the second box.
Cutting the full flat box pattern.
Folding the two sides on the bending brake. Notice the mistake of flattening the 1/2" lips.
