True Modeler's Rocket Kits NASA Scout Build, Part 6, Balsa Adapter Filling

I had to sand down the low edge of the balsa adapter to better match the diameter of the BT-60 tube. You've got to use a sanding block to do this. Sand a little, check the fit in the tube, sand some more.

To sharpen up the shoulders -
Paint some CWF over the edge of the shoulder lip. Slide the upper tube down into the the filler and turn the tube. This will cause a filler lip bead to form.

Turn and lift off the upper tube.
Notice the filler bead left at the joint. When this is sanded down with a block you'll have a sharp, cleaner edge where it meets the body tube.

On the right is the same application on the bottom of the balsa adapter.