3D Printing for FYPs: Mechanisms, Gears and Electronics Enclosures.

3D printing lets an FYP team make mechanisms, mounts and electronics enclosures in days instead of waiting for machined parts. This guide covers the two jobs students most often print: moving mechanical parts, such as gears and grippers, and enclosures that hold the electronics. It explains print settings, fits and material choices that work for a final demonstration.

Print settings for strong mechanical parts

• Walls before infill: four to six perimeter walls add more strength than raising infill. Two walls with 60% infill is usually weaker than five walls with 30%.
• Orient for the load: FDM parts are weakest between layers. Lay the part so bending or pulling loads run along the printed lines.
• Use gyroid or cubic infill: these spread load more evenly than a simple grid.
• Choose a tough material: PETG for most parts, nylon or carbon-fibre nylon for gears and high loads. See the filament guide.

Mechanisms that work well when printed

• Gearboxes: planetary and cycloidal reducers for robot joints and slow actuators. Use a gear module of at least 1.5 to 2 mm, print the hub solid, and lock the shaft with a metal D-shaft or set screw rather than relying on plastic alone.
• Grippers: linkage grippers in PETG, or flexible fingers in TPU, for pick-and-place arms.
• Wheel hubs and suspension arms: for small rovers and robots, with bearings pressed in.
• Mounts and brackets: motor, sensor and camera mounts that would be slow to machine.

Bearings, shafts and fits

FDM holes usually print 0.2 to 0.4 mm undersize. For a bearing press fit, start with a hole 0.1 to 0.2 mm larger than the bearing's outer diameter, print a test ring and adjust. Leave 0.3 to 0.4 mm clearance per side for parts that slide or rotate. Add a small recess at the bottom of bearing pockets so the first-layer squish does not block the bearing. The tolerance chart lists values for resin and nylon too.

Designing an electronics enclosure for your FYP

A tidy enclosure makes a prototype easier to carry, demonstrate and defend. Design it around the actual boards and connectors, not a guess.

• Port cutouts: measure every USB, DC jack and antenna connector, and leave about 0.5 mm clearance around each.
• Display and button openings: add a recess or bezel so OLED or touch screens sit flush.
• PCB standoffs: raise boards 4 to 6 mm on printed bosses with M2.5 or M3 heat-set inserts. Leave 0.8 to 1.2 mm clearance between the board edge and the wall.
• Ventilation: put vents above motor drivers and voltage regulators. A printed shell traps heat.
• Service access: use screws or snap fits so you can open the box during testing.
• Wall thickness: 2 to 3 mm keeps FDM enclosures stiff without warping.

Enclosure material by use

An enclosure does not make wiring or batteries safe on its own. Fuse your battery, secure loose wires and test the closed box at full load before the defence.

For the bigger picture of building an FYP, see turning an FYP prototype into a demonstrable product. PakMEC can print FYP parts in FDM, resin, SLS, MJF or metal through its 3D printing service, and help with CAD through FYP development support.

Frequently asked questions