Estes Cosmic Interceptor Build, Part 22, Root Edge Fit

The supplied fin marking guide fit!

The root edge contact positions (two on each of the main wing fins) had the filler/primer scraped off for better adhesion. 

A dry fit of the wings showed the lower root edge not making complete contact. The upper root edge was good.

The root edge was sanded with 320 grit on a block until the fin made full contact down the fin / body tube joint.

New Way Letter - Go Build, Part 8, Sanding the CWF & Filler/Primer

Here's the tube fill after working the CWF into the seams.

I usually hit the filler with 400 grit on a sanding block to start.

Take a close look at the end of the launch lug. That edge is rough and needs same sanding with 400 grit on a block.

On the left, there is already sanded CWF filler in the lug.

After sanding the ends clean, use a sharpened dowel to round the lug and clean up the inside wall. 

Thin strips of masking tape kept the filler primer of the root edge gluing areas.

On the right is the tube after sanding the filler/primer and pulling of the masking tape strips.