Estes Hi-Flier XL, #3226 Build, Part 7, Making A Baffle

You can make an internal fillet by applying a line of glue just inside the edge of the coupler.
Then apply a second bead of glue on the upper edge.





TIP: While the glue is still wet, set the disk on the end of the coupler and turn the disk.
This smooths out the glue bead inside the coupler edge. You should end up with a pretty even interior glue fillet.

After the glue is totally dry, sand off the overhanging edges.

Here I am sanding only with down strokes so I can't pull up and loosen the cap edge.
Use 220 grit and the edge should come off easily.

Here's the finished coupler/baffle.

Before gluing the coupler into the body tube ends,
TEST FIT (no glue) and SAND, 
TEST FIT (no glue) and SAND, 
TEST FIT (no glue) and SAND.

You may have to go over the baffle ends a few times for a sliding, smooth fit in the tubes.
I might use epoxy to insure there is no chance of it seizing up in the wrong position.