Estes Asteroid Hunter #3224, Build, Part 17, Fitting the Q Piece Sides

Check the root edges where the fin sides exit the skin slots. 

If there are any raised areas - 

You can press them down before the glue fillets are applied. Try to get the sides as straight as you can. These edges will be covered with fillets, but if they are flat they will look better in the end.

The slots in the "Q" side pieces were smaller than the thickness of my filled fins. Notice where the glue fillet stops to allow the end of the Q piece to slide in.

I had to widen the slots with a flat diamond file.

The slot is rounded, but the leading edge of the fins are square! There is a round gap in front of the squared leading edge of the fin.

Note the front of the Q piece. It should slightly overhang the front of the angled top assembly.

That slight overhang should allow me to taper the rear slot and still fit the front.

Tapering the inside of the slot will move the fin back and give a little tighter fit at the leading edge gap.