I went "old school" and made my own fin marking guide.
A 2 1/2" wide strip of paper was cut from some 20 lb. printer paper. Be sure you cut the strip in a true rectangle, it's just easier to line up the ends.
Cut it longer than you'll need, more than a full wrap around the tube.
Wrap, mark and cut off the excess.
Fold in half and mark the folds with pencil.
Fold in fourths (using the half fold lines you just made) and mark those folds.
TIP: After you mark the fin locations using a marking wrap, rotate the wrap around the tube and check the other pencil marks you just made.
Simply slide the guide around the tube 90 degrees to the next mark on the tube. Check all four fins. Rotate and check again.
Even if you are using a marking guide supplied in a kit - Double check your fin markings!
If you still don't have an aluminum angle to mark body tubes - what are you waiting for?
This one is 3/4" on a side. One single guide is used on everything from a BT-5 to a BT-70.
The BT-5 fit in the V groove is a little small, but still usable.
Home Depot and Lowe's carry them in 36" lengths.
Cut it in half with a hacksaw, and file the end smooth.
This is a valuable tool for any rocket builder. I use it on every build.
After drawing the fin placement lines, The paper guide was slid to a position just below the leading edge position of the fin. Using the wrap edge, a tick mark was made.
For a better gluing bond, the fin line will be lightly rough sanded using 220 grit on a block. The upper "stop" tick mark was drawn as a reference so I won't rough up the body tube beyond the leading edge of the fin.
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