Tube Slotting and Cutting Guide

Cut your own slots for 1/8 inch thick through-the-wall fins in cardboard airframe tubes with this sturdy plastic tube slotting guide!  It's also useful as a tube cutting guide, helping you cut straight cuts perpendicular to the tube. Works directly with 3 or 4 fin patterns up to 85mm in length although you can slide the guide up the tube and realign to cut longer slots. You can also rotate the tool after cutting 3 or 4 fins to align and cut 6 or 8 fins. To cut a fin slot, slide the guide tool around a cardboard tube, align the aft end of slot guide with the tube where you want to slot the tube, and slide the tightening ring onto the forward end of the slotting guide to secure the guide in place. Mark the fin slots to match the length of the fin slot you need.  Then, using a new, sharp hobby knife, lightly score the tube along the 2 sides of the plastic guide slot. Do not stab directly through the tube; use 3 or more cuts to gradually cut through the tube. This will help avoid crimping the tube with a heavy downward force. Direct the cutting force parallel to the tube wall. After cutting the 2 long edges of the slot, gently score across the ends of the slot, taking care not to press hard down into the tube. Drag the blade gently across the tube, taking 3 or more slices to cut through the tube.  Repeat for the other fin slots, making sure you are cutting the labeled slot guides for the fin pattern you need.