Estes Blackhawk #2053 Build, Part 4, Cutting The Vent Holes

Hoo Boy! This is a tough cut to make. I wouldn't usually put in a new #11 blade, but for this cut it is needed. 

The guide is wrapped and taped so it can't move.

Score the oval cut then remove the guide.

Cut, cut and cut some more. Going through the old style fish paper coupler takes many passes.

 

On the left side picture you can see the two layers of tube and coupler. That tube cut reminds me of Pac Man.

My scanned cutting guide must have been small. The engine mount tube wouldn't slide in.

I wrapped some 220 grit around an used engine casing and rotated it in the side vent hole.

Right side picture:

Looking up the engine mount from the rear.

I've marked with a pencil where the fit was tight and needed a bit more sanding for a friction fit without any tube distortion.