Cutting motor ports into aluminum R2 battery boxes

I thought I'd offer some guidance here about how to cut the motor ports out of the battery boxes.

First, the dimensions:

Notice that there should be a right and left motor port, and that the port should be cut on the same end as the knurled hose fitting holes:

There are several ways you could make these cuts, depending on what equipment you have.  I use the table saw, a compound miter saw, and a grinder with a metal cut off wheel to make the cuts.

I set the fence so that the cut here would be at 1" from the left edge, I clamped a stop block to the fence so that the blade would only cut to 3.5" inches into the body, and I set the height of the saw blade so that it only cuts 1.5" up.  Measure twice, or three times, and don't get this wrong.  For the other parallel cut, you can keep the stop block in the same place, and the blade at the same height, and just move the fence over.

For the cut on the body, I use the compound miter saw:

Again, I set a stop block on the fence.  It's on the right behind the blade.  It set so that this cut is 3.5" from the outside edge of the box.  And I carefully plunge the blade down and in (take care, the blade can catch) until the cut just meets the other two at the corners.

For the last cut along the curved spine of the battery box, I use a metal cut off wheel on my grinder.  I clamp the grinder on top of blocks to get it 1.5" off the table top.  Then I carefully plunge the box into it to make the cut.  This method is slower than the others but it's the best way I've got to cut the curved side of the box.

I hope that helps.