Estes Black Brant XII, Kit # 9723 Build, Part 4, Prepping The Fin Pieces

I've mentioned this a few times before - 

Laser cut fins are great! Except, the laser cut beam is diffused when it cuts into the balsa sheet.

Look at both sides of the sheet. On one side of the sheet, the line will be wider. It is a angled "wedge" cut.

Square up the fins setting the at a 90 degree angle on your sanding block. The right side picture shows the fin edge after light sanding. Some of the angle and the hold down tic has been sanded.

After gluing up a few of the fin sets - 

TIP: I recommend gluing together the outside halves (Parts L & M) together FIRST before joining to the center tabbed balsa layer. There will be too much sliding around when the laminate layers are glued up. It's easier with the L and M pieces joined beforehand.

TIP: You can use your block to square up the root edges.

On the right is the "M" piece. Notice the notch and most of the front root edge is slightly raised. Don't sand or remove this raised root edge area.