Left Wing Trailing Edge Slots

We are in the process of cutting slots in the trailing edge of the left wing.  These slots are for the flap and aileron hinges that will (eventually) be attached to the wing ribs and protrude through these slots.  The instruction manual suggests chain-drilling to create a slot.  We tried this method, and also tried a few other methods including using a Dremel rotary tool with a cutting bit, and a  Dremel multi-tool with a vibrating cutting bit.  No method seemed superior to another, but regardless of the method used, extreme care was taken so that the ends of the ribs (which are centered between a pair of slots), were not nicked.  Once a rough slot was created, the edges were fixed and smoothed with files.  One side of each slot was filed back so that it was even with the edge of the rib.

Two slots in the left wing for the aileron hinges

There will be a total of 12 slots in the trailing edge, 6 for the ailerons, and 6 for the flaps.  We opened up 10 of them so far, so just have a few more to go for this wing.  Hours: 2.5