Estes Astron Explorer tube cutting templates

The Estes Astron Explorer is a super cool rocket where the exhaust gas from the ejection charge has to route through 3 external tubes to go from the bottom body tube to the top body tube. In order to accomplish this, you have to cut a bunch of very precise slots in the BT-20 and BT-55 body tubes. In order to simplify this process and make it much more precise, I created these body tube slot cutting templates. There is 1 for the BT-20 tubes and the other is for the BT-55 tubes. 

Instructions for printing: I printed these with 15% lightning infill and only 2 top and bottom layers on a Prusa I3mk2 to save filament and decrease printing time. Printed out of Hatchbox white PLA. 

Instructions for use:

BT-20 Template - First, mark a line all the way down the tube using a door jam or marking guide. Next, insert the tube all the way into the template until the tube bottoms out. Align the line you made with the pencil slot at the top of the template. Mark the tube on the opposite side using the pencil slot (this will give you 2 lines 180 degrees apart). Remove the tube and use this mark to make another line on the tube. Insert the tube back into the template, aligning one of the lines with the pencil slot. Use a hobby knife to cut the tube through the main slot. Remove the tube and flip it over and insert the other end, make sure to keep the slot you just cut on the same side as the main slot. Cut the second slot and remove the tub. 

BT-55 Template - There are 2 sets of main slots on this model. The lower of the main slots is for the top (longer) tube and the upper of the main slots are for the bottom (shorter) tube. These directions work regardless of which slot you are cutting just make sure you are cutting the right slots in the right tubes. First, mark a line all the way down the tube using a door jam or marking guide. Next, insert the tube all the way into the template until the tube bottoms out. Align the line you made with the pencil slot at the top of the template. Mark the tube using the pencil slots that are 120 degrees from the line. Remove the tube and use these marks to make 2 more lines on the tube. This will give you 3 evenly spaced lines around the tube. Put the tube back into the guide. There are holes above 2 of the main slots. Select which main slot you are using and put a pencil into the slot. Rotate the tube 360 degrees to draw a line around the tube (you will use this later to line up the BT-20 tubes when gluing everything together). Finally, line up the vertical lines with the pencil slots that are 60 degrees from the slot you are cutting. Use a hobby knife to cut the tube through the main slots. Another way to think of this is you will NOT be cutting the slots into the lines. If you are confused about this step, reference the Estes instructions/templates and it should be clear. Repeat on the other tube using the other main slots. 

Hopefully my instructions make sense. If not, leave me a comment on what is confusing and I can try and make it more clear. Hopefully these templates help you get your rocket perfect!