Ever had a passion for 3D printing and rocketry but didn't know how to combine the two? Well look no further than this guide on building your own model rocket using nothing more than a 3D printer!

This project was inspired by a desire to create a functioning rocket that could perform just as well as any store bought kit while also providing far better structure and resistance to damage. I wanted to be able to create a rocket without requiring all the additional tools you need for most kits this size: adhesives and tools that take hours to set and a single mistake could put you out an entire kit.

Not here! Instead I looked to create a series of parts that allow for replacing only sections of the rocket in case of failure. Whereas with a kit you might break a fin and have to replace the entire lower portion of a rocket, you only need replace the single broken fin and be up and running again without a moments notice.

This guide will lead you through building your own model rocket in Fusion360 along with any tips or advice I discovered through the development process.

Supplies

Software:

Fusion360
Cura

Building your Rocket:

3D Printer (with a minimum build height of 192.5 mm in the case of my design)
Filament ( I use PLA which has worked just fine for multiple launches)

Launching Your Rocket (Not exhaustive, please look at local rules and regulations):

Parachute
Parachute Cord
2 Eyebolts
Launch Stand
Launch Controller
Motors

Step 1: Design the Upper Rocket Body's Lower Section

We can start with any part of the rocket, but one of the simplest portions will be the section of the rocket that will connect with the lower rocket body. Here there are 4 key features: the launch lug, bulkhead/ mounting hole, and upper threads.

First, we must create the tube of the rocket. Using a commonly available rocket diameter will let you select motors and launch materials in line with commercially available systems, so I have chosen an outer diameter of 75 mm. I then decided an inner diameter of 69 mm to create a wall thickness to provide durable structure while not being overly heavy.

Now we have the launch lug, this component is used with the launch stand to provide your rocket a fixed direction of motion: upwards. There will be a second lug attached to the lower body for stability that will mirror this one. Depending on the size of the launch rail's rod, the inner hole of your lug will change, however for mine I chose a diameter of 7.50 mm. This is then followed by an outer diameter of 9.5 mm to create a simple hole for the launch rod to run through. You must also make sure that the length of your lug is not too long or too short. A longer lug provides more structure, but also increases the friction while the rocket travels up the rod, resulting in a lower off-the-rail speed and therefore lower peak altitude.

Next we have the bulkhead and mounting hole. This is to create a separation between your upper rocket body that can house any additional electronics and payload. The mounting hole also provides a point to connection your upper and lower rocket bodies together with your parachute cord. This is a simple design, you merely will create a solid wall of a minimum of 5mm thickness with around 70 mm of spacing between the bottom of the bulkhead and the bottom of the Upper Rocket's Lower Body. This will allow you to use a Fillet to curve the bottom of the bulkhead downward to create an easier to print curvature rather than a flat face. You will also wish to add a lip on the inside of this lower section to allow for a snug but loose fit with the lower rocket body. This joint is meant to separate due to the ejection charge of your rocket and therefore should not be too tight, otherwise you run the risk of containing the pressure inside the rocket body until it bursts.

Next we add some small threads to the upper portion of this body to connect to the second portion of the rocket body, these can be any size threads or any other form of connection if you wish to make it permanent with glue.

Step 2: Designing the Upper Rocket Body's Upper Portion

This portion is quite simple, you only need two key parts: upper threads and lower threads.

The lower threads should be the opposite of the threads you created on the lower portion of the upper body. That way these two pieces will lock and stay together. They should match the same length as your lower portion or slightly shorter to ensure the rocket body does not have any gaps at the joint.

The upper threads shall be used to connect the nose cone of your rocket to your upper body. These do not have to be as strong or deep as the lower threads as you are holding a lighter piece that is not subjected to as great of force.

Step 3: Designing the Nose Cone

Here we created a simple pyramid with threads to match the upper body's upper threads, this will lock whatever is stored in the upper body and keep it from coming loose during flight and fall.

A method of making the nose cone is a side profile that is revolved around a a center point. You can then insert the threads after making the initial cone.

Step 4: Designing the Lower Rocket Body's Upper Portion

The upper portion of the lower body contains two especially important features: the baffle and the mounting point.

Much like the Lower Portion of the upper body, you have a simple press fit to connect the upper and lower rocket bodies together to be separated during parachute deployment.

Additionally you have a bulk head with a mounting point for an additional eye hole to attach the other end of your parachute cord to.

The more intricate section of this part is the baffle. A baffle is used to provide a physical method of trapping burning material from the rocket ejection charge without the use of recovery wadding. Instead it catches burning material in the inner tube and allows the hot gases to escape through the smaller outer holes. This inner tube will fit over the motor tube while still allowing enough room for the gases to maneuver.

Lastly you have a set of threads to connect to the lower portion of the lower body. These should once again be strong enough to hold the two portions together, be advised that longer threads can get pretty exhausting to turn over and over so choose your thread size carefully.

Step 5: Designing the Lower Rocket Body's Lower Portion

This last portion contains our physical motor and fins.

For the motor we must take into account the size of the motor we wish to use. For this style of rocket we commonly use motors that are around 30 mm in diameter so we will create a tube to fit this size. Next we create slots for our fins along with a set of threads to seal the fins once they have been inserted. This will allow us to replace broken fins quickly without replacing the entire lower portion.

Finally we have the motor thread, this will allow us to seal the motor in place to prevent it from moving or escaping from the rocket body during use.

Step 6: Designing Fins

The fins should have a profile that matches the cut-out in the lower portion of the lower body, this way it can slide inside and be held in. Something in the shape of an "L" or "T" would provide a snug fit while also preventing the fin from merely falling out.

Your fin design can be whatever you want, but make sure there is a space between the full body of the fin and the rocket tube. This will allow your lower launch lug to not interfere with the fins when screwed on.

Step 7: Print

I used a standard Ender 3 printer to be able to print all of these parts. My infill was only 15 % which saved on weight while still providing structure.

A thing to note is overhangs and supports. Several parts such as the Lower Body Lower Portion will need supports in connection with the build plate or else your printer will struggle to connect sections such as the fin threads.

Always watch your printer and identify any changes you need make first rather than coming back hours later to find a ruined print and wasted filament.

Step 8: Assemble

Make sure to sand the connection between the upper and lower bodies. It should be a firm connection but not too tight to prevent parachute deployment.

Also some threads might be tighter and more friction, you can use soap on the threads to aid in a smoother performance.

Make sure that your eye bolts are connected securely to the Upper Portion of the Lower body and the Lower Portion of the Upper Body (Confusing I know). Using a parachute cord ,you can then connect your parachute to this line and then fold and insert it inside the lower rocket body.

Step 9: Launch!

Always follow all required safety rules and regulations for your location and rocketry class. Do not fire without permission of required persons and always be aware of your surroundings.

When in doubt, look for resources such as the National Association of Rocketry:

https://www.nar.org/

I hope everything goes well and thank you for checking this instructable out! As this is my first time instructable if you have any comments or advice for me moving forward I would super appreciate it.

Thanks!