Estes Boosted Bertha #001946 Build, Part 6, Fin Marking & Booster Mount Gluing

Join the booster and sustainer segments with the coupler . . . No glue yet.
TIP: Instead of using the wrap-around marking guides, use the booster fin slots to mark the upper stage fin locations. Slide both tubes together with the coupler. Set your aluminum angle on the booster fin slots and extend pencil lines onto the upper body tube.

The face of the booster centering ring is even with the tube end.
The mount is slid in halfway, then run a ring of glue around the inside edge of the tube. Press the mount the rest of the way in. I used the flat side of my sanding block to get the ends even.






A glue fillet was applied from the top.
Yep, I go through a lot of Q-tips.