Making subpanel cutout^6h

The next big task was to make a hole in the subpanel for the central avionics stack.

The idea was to make a hole in the subpanel to make room for the longer units in the central stack (GTN650 being the longest). First, I calculated the location of the hole based on the units I plan to install:

Since this hole weakens the subpanel, I reinforced it with angles. Two angles go horizontally on the back and two angles go vertically on the front.

Everything is drilled together.

Then I cut the hole using the Bad Dog Biter Nibbler tool.

And smoothed it with my angle grinder and ball-bearing router bit. While doing that, I cut a bit into the horizontal angles, so I decided to replace them with new ones.

The parts are primed.

And the installed cutout looks like this. The horizontal angles will transfer side-to-side loads (to reinforce the weakened flange), and the vertical angles will be used to attach the back of the avionics stack.