3D Printing for FRC

3D printing is useful when you need complex geometry fast, especially for parts that would be difficult or expensive to machine. However, printed parts are weaker than aluminum and can fail if designed or oriented poorly. Knowing when to print, what material to use, and how to design for printing is what makes the difference between parts that hold up at competition and parts that crack on the field.

When to print vs. when not to

Good use cases

• Custom spacers for hex shafts

• Sensor mounts and camera mounts

• Cable guides and wire management clips

• Pulleys with custom tooth counts or bore sizes

• Intake funnels and game piece guides

• Prototypes of any kind

3D Printable Snap-On Spacers

We didn't necessarily use this but it's a 3D printed camera mount!

Bad use cases

Materials

Material	Strength	Heat resistance	When to use
PLA	Low	Low (softens around 60C)	Prototypes
PETG	Medium	Medium (around 75C)	The default for competition parts. Good balance of strength, ease of printing, and heat resistance.
Nylon	High	High (80C+)	High-load parts, gears, anything that takes repeated impact. Harder to print (needs dry filament and often an enclosure).
TPU	Low (but very flexible)	Medium	Flexible parts like bumper padding, vibration dampening mounts, impact-absorbing camera mounts.
CF-Nylon / CF-PETG	Very high	High	Strongest option. Use where you'd consider aluminum but want to print instead. Requires a hardened nozzle.

If you only stock one filament for competition parts, make it PETG. It handles most FRC applications well and is not significantly harder to print than PLA.

Print orientation

This is the single most important factor in how strong a printed part is. Layers bond to each other much more weakly than the material within a single layer. This means a part will almost always fail by splitting between layers.

The rule: orient the part so that the primary load goes across the layers, not along the layer boundaries.

A hook printed standing upright will snap at the layer lines when you hang weight from it. The same hook printed on its side is significantly stronger because the load goes across continuous filament paths rather than between layers.

When you can't avoid bad orientation: if the part geometry means some areas will be loaded along the layer lines no matter what, increase the wall count in those areas or redesign the part to distribute the load differently. Adding fillets to inside corners also helps prevent cracks from starting at layer boundaries.

Slicer settings that matter

Setting	Recommendation	Why
Layer height	0.2mm for competition parts, 0.3mm for prototypes	Finer layers bond better and produce stronger parts, but take longer
Wall count	3 to 4 minimum	Walls carry the structural load. More walls help more than more infill.
Infill	20 to 30% for most parts	Going above 40% rarely adds meaningful strength for the added weight and print time
Infill pattern	Gyroid or cubic	These patterns provide strength in all directions, unlike lines or grid which are strong in only two
Top/bottom layers	4+	Prevents infill pattern from showing through the surface

Design tips

Tip	Why
Add fillets to inside corners	Sharp inside corners are where cracks start between layers. Even a 1 to 2mm radius makes a big difference.
Design holes .005" oversized	Printers tend to shrink holes slightly. Test on your specific printer and adjust.
Use hex pockets for captive nuts	Design a hex-shaped pocket into the print so a nut drops in and is held in place. Saves you from needing to hold a wrench on the back side.
Use heat-set inserts for bolted connections	If a printed part will be bolted and unbolted multiple times, a brass heat-set insert gives you strong metal threads instead of threading directly into plastic.
Avoid tall thin features	They wobble during printing and come out weak. Add a base or fillet to stabilize them.

More on heat-set inserts

Heat-set inserts are small brass threaded inserts that you push into a hole in the print using a soldering iron tip. The heat melts the surrounding plastic, and when it cools the insert is locked in place with strong metal threads.

Use the hole diameter recommended by the insert manufacturer (usually slightly smaller than the insert's outer diameter). Common sizes for FRC are M3, M4, and #10-32. These are available cheaply from McMaster or Amazon.