How to 3D print a combat robot 

3D printing is now an integral part of modern hobby and professional robotic engineering. With 3D printing, you can:

• Quickly and cheaply produce complex parts exactly according to your own designs
• Customize and iterate the design during development without the need for complex milling or machining
• Save weight thanks to optimized internal structures (such as reinforced grids)
• Create unique shapes and functional elements that would otherwise be difficult to manufacture

1. Designing parts in CAD software
   Free programs like Fusion 360 or OnShape allow you to create a precise model based on dimensions and functional requirements.
2. Export to STL or 3MF
   The created model must be exported to STL or 3MF format so that the print software can understand it.
3. Uploading the model to a slicer
   To ensure the printer knows how to manufacture the part, the model must be uploaded to a printing program called a “slicer.” In the slicer, the model is cut into individual layers with instructions on where the material should be placed; the printer then uses this data during the printing process.
4. Choosing the right material and print settings
   Select a suitable filament based on your requirements and set the correct nozzle temperature, print speed, and layer height.
5. Printing
   It is recommended to print at a low speed for higher quality and better layer adhesion.
6. Post-processing
   Remove supports, sand the surface if necessary, or insert threaded nuts.
7. Testing and modifications
   After the first production, test the part in real conditions. If necessary, adjust the CAD model and print a new version.

 

Filament selection

Material is absolutely critical for the robot’s durability.

• PLA/PLA+: Great for printing initial prototypes. It is easy to print and cheap, but relatively brittle. Not ideal for combat.

• Overture Super PLA+ / eSun PLA-ST: Special PLA blends created to be as tough as possible. The advantage is that they retain the ease of printing of regular PLA, so you can print them on any printer while obtaining very durable parts, or even entire bodies for antweight robots.

• PETG: It is stronger and more flexible than regular PLA, so it handles impacts better, but is still too weak for combat.

• ABS/ASA: Durable, but harder to print as it requires higher temperatures and ideally an enclosed printer. It has low inter-layer adhesion, but also low density, making parts lighter. Can be used for parts that do not receive direct hits, or do so in a direction perpendicular to the layers.

• TPU: An extremely durable and flexible material. It can absorb a huge amount of impact energy. Some robots even have entire bodies made of TPU. However, printing is slower and more demanding regarding correct printer settings. It comes in various hardnesses; soft and flexible variants are more durable but do not hold their shape and are thus not ideal for building a frame. However, TPU is a very suitable choice for armor.

• Polycarbonate (PC): Demanding to print because it requires high nozzle temperatures (around 275 °C), a heated bed, and a closed printing chamber. The results are very rigid and strong parts that handle normal impacts well. However, in extreme collisions typical for combat robots, the material can crack.

• Nylon (PA) or Carbon Fiber Filled Nylon: The absolute top tier in durability. It is extremely tough and strong. Printing it is demanding, however – it requires high temperatures and often a special hardened nozzle.

Recommendation for beginners: Start with Super PLA+ or PLA-ST. Once you gain experience, you can experiment with TPU or Nylon.

Print preparation in slicer

Software called a “slicer” (e.g., PrusaSlicer, Bambu Studio) converts your STL model into instructions for the printer (G-code). This is where you set the key parameters for strength:

• Layer height: Lower layers mean stronger bonding, but a longer print time.

• Nozzle diameter: With a larger nozzle, you are able to extrude more material in a single pass, which positively influences the resulting strength at the cost of the ability to create finer details in the model.

• Number of perimeters (walls): This is the most important setting for strength! Most of a part’s strength lies in the outer walls, not the infill.

• Infill: Set a high density, ideally 50–100%. Gyroid or cubic are excellent infill patterns because they are strong in all directions.

• Part orientation: As mentioned above, place the part on the virtual build plate so that the layers lie perpendicular to the direction of expected impacts.

• Print temperature: For combat robots, it is advisable to print at the upper limit of the material’s recommended temperature range. Higher temperatures ensure better heating of the layers and stronger bonding, which minimizes the risk of the part tearing apart during an impact.

Supports: These are temporary structures that hold parts of the model “in mid-air.” For robots, try to eliminate the need for them, for example by using chamfered edges, because the contact points of supports are usually structurally weaker. If they are necessary, set them to provide firm support while still being easy to remove, so you don’t damage the load-bearing parts of the part.
Brim: This is a layer of material printed around the base of the object. For combat robots, it is essential because it prevents the part from warping while cooling. A wide brim ensures that the model does not peel off the print bed during printing, which is critical for materials like Nylon or PC.

Printing and post-processing

• Prepare the printer: Make sure you have a clean and well-adhering print bed.

• Start the print: Printing larger parts can take many hours. Be patient.

• Finishing: After printing, let the part cool down, carefully remove it from the print bed, remove any supports, and clean up the edges.

• Assembly: Install all the components. You may need to slightly enlarge some screw holes with a drill bit, which is completely normal.

 

Tips for 3D printing combat robots

• Modularity – print parts as separate modules for easy replacement and repairs.

• Dimensional accuracy and fit tolerances – overly tight joints can be a problem; it is better to leave slight clearances (0.1–0.2 mm).

• Printing can be paused – during a pause, you can insert items like nuts directly into the part and print over them, sealing them inside the model.

Your first design will almost certainly not be perfect. Don’t be afraid to iterate! Build the robot, go fight, find out what broke, and based on that, improve the model and print a new, more durable version. That is the true beauty of 3D printing and combat robots.