QIDI i-Fast Dual Normal Extruder with X-Axis Rail

The QIDI i-Fast Dual Normal Extruder with X-Axis Rail is a complete upgrade kit that transforms the single-extruder QIDI i-Fast into a dual-extrusion 3D printer with linear-rail precision, enabling two-color printing, soluble support structures, and dual-material prints at temperatures up to 250°C for $179.99.

This kit replaces the stock single extruder carriage with a dual direct-drive extruder assembly and upgrades the X-axis from V-wheel rollers to a precision linear rail. The dual extruders support independent nozzle temperature control, allowing you to print two colors, two materials, or use soluble support (PVA/HIPS) for complex overhangs. The X-axis linear rail eliminates V-wheel wear, reduces vibration, and improves print surface quality — especially at high speeds.

Product Specifications

What's Included in the Kit

How the Dual Extruder Works

The dual extruder assembly features two independent direct-drive extruders mounted side by side on a single carriage. Each extruder has its own nozzle, heating element, thermistor, and cooling fan. The printer firmware (QIDI Slicer / QIDI Studio) controls which extruder is active at any given time.

Dual Extrusion Modes

X-Axis Linear Rail Benefits

• Zero maintenance: Linear rails do not require tightening or replacement like V-wheels (which wear every 6-12 months).
• Better precision: Linear rails have ±0.02mm repeatability vs ±0.05mm for V-wheels.
• Less vibration: Rigid rail connection reduces print head oscillation, improving surface finish at high speeds.
• Higher speed capability: Linear rails can handle 200+ mm/s print speeds without quality loss.
• Longer lifespan: Linear rails last 5+ years vs 1-2 years for V-wheels.
• Quieter operation: Linear rails produce less noise than V-wheels on aluminum extrusion.

Installation Overview

1. Power off and unplug the i-Fast printer. Allow all components to cool.
2. Remove the old extruder carriage by disconnecting the wiring harness and unbolting the carriage from the X-axis V-wheel assembly.
3. Remove the X-axis V-wheel rail from the gantry. Keep the original hardware in case you need to revert.
4. Install the new MGN12 linear rail using the included mounting brackets. Ensure the rail is parallel to the Y-axis gantry.
5. Mount the carriage adapter plate to the linear rail carriage blocks.
6. Attach the dual extruder assembly to the carriage adapter plate using the included screws.
7. Route the wiring harness along the existing cable chain, connecting to the mainboard. Match labels (E1, E2, FAN1, FAN2, T1, T2).
8. Verify all connections are secure. No loose wires or pinched cables.
9. Power on and update firmware to the dual-extruder version (available on QIDI website).
10. Calibrate nozzle offset (X and Y offset between Extruder 1 and Extruder 2) using the calibration wizard in QIDI Studio.
11. Run a test print — a two-color calibration cube to verify both extruders work correctly.

Performance Comparison: Before vs After Upgrade

Pros & Cons

Dual Extrusion Printing Tips

Two-Color Printing

• Use a prime tower (5-10mm diameter) to purge the inactive nozzle before each switch.
• Set the inactive nozzle temperature 10-20°C lower to reduce oozing.
• Enable "wipe tower" or "ooze shield" in QIDI Studio to catch stray filament.
• Calibrate X/Y nozzle offset carefully — even 0.1mm error causes visible misalignment.
• Use the same filament brand/type for both colors to ensure consistent flow rates.

Soluble Support (PVA/HIPS)

• Dry PVA filament before use (45°C for 4-6 hours) — wet PVA causes bubbling and clogging.
• Store PVA in an airtight container with desiccant when not in use.
• Use PVA for support only, not for the model — PVA is expensive and slow to dissolve.
• Dissolve PVA in warm water (40-50°C) for 4-12 hours, depending on part size.
• HIPS dissolves in limonene (citrus-based solvent) — use for ABS models with HIPS support.
• Set support extruder temperature: PVA 180-200°C, HIPS 220-240°C.

Dual-Material Printing

• Rigid + flexible combinations (PLA + TPU) work well for grips, hinges, and seals.
• Ensure both materials have similar printing temperatures (within 30°C) for best results.
• Use a higher infill for the rigid material and lower for flexible material.
• Enable "prime tower" to purge each material before switching.
• Design parts with material boundaries on flat surfaces for clean transitions.

Compatible Printers & Filaments

Real-World Use Cases

• Two-color figurines and models — Print skin tone and clothing color in one print without painting.
• Soluble support for complex parts — Print mechanical assemblies with internal cavities using PVA support.
• Rigid + flexible parts — PLA housing with TPU gasket or grip in a single print.
• Multi-material prototypes — Test different material combinations without assembly.
• Batch production (mirror mode) — Print two identical parts simultaneously for doubled throughput.
• Text and logos — Print raised text in a contrasting color on a model surface.
• Water-soluble supports — Dissolve PVA in water for smooth overhangs without support marks.
• High-speed printing — Linear rail enables 150-200 mm/s printing with quality surface finish.

Frequently Asked Questions