Extruder

The extruder is the motor-driven mechanism that grips filament and pushes it toward the hotend. It’s sometimes called the “cold end” because it handles filament before it’s melted.

How It Works

1. Motor turns a drive gear (often with teeth)
2. Filament is pressed between drive gear and idler bearing
3. Gear teeth grip filament and push it forward
4. Filament moves toward the hotend

Types of Extruders

Direct Drive

Extruder mounted directly on the print head:

• Pros: Better retraction, prints flexibles well, precise control
• Cons: Adds weight to print head, potentially slower

Bowden

Extruder mounted on frame, filament travels through PTFE tube:

• Pros: Lighter print head, faster movement possible
• Cons: More retraction needed, harder to print flexibles

Single vs. Dual Gear

• Single gear: One drive gear, simpler
• Dual gear: Two gears grip both sides, more grip, less slipping

Common Issues

Grinding/Slipping

• Filament gets chewed up by drive gear
• Causes: Nozzle clog, too fast extrusion, idler too loose/tight

Under-extrusion

• Not enough filament comes out
• Causes: Partial clog, wrong e-steps, worn drive gear

Clicking/Skipping

• Motor skips steps
• Causes: Too much resistance, temperature too low, clog

Maintenance

• Check drive gear teeth for debris
• Adjust idler tension—firm but not crushing
• Clean dust and filament particles
• Lubricate gear shaft if needed