Creality SPARKX i7: TPU & Flexible Filament Printing Guide

Flexible filaments like TPU open the door to printing soft, impact-resistant, and bendable parts — perfect for phone cases, seals, wearables, and functional components. However, flexible materials behave very differently from PLA or ABS. 

This guide walks you through how to successfully print TPU and other flexible filaments with the Creality SPARKX i7. 

Selecting Your Material: The Hardness Scale

The most important factor in flexible printing is the Shore Hardness. Flexible filaments range from "stiff like a shopping cart wheel" to "soft like a rubber band."

The hardness order from hardest to softest is:

77D > 70D > 68D > 55D > 95A > 85A > 83A > 80A > 75A > 70A.

Hardness Recommendations for the i7:

• SPARKX i7 (Standalone): Supports 95A or higher. This is the standard hardness for most "Easy TPU" on the market.
• i7 with CFS Lite (Color/Autofill Combo): Because the CFS Lite must push filament through long tubes, you must use stiffer flexibles with a hardness of 64D or higher. Attempting to use soft 95A in the CFS Lite may lead to jams.

⚠️ If using CFS Lite, the TPU must be 64D or harder.

Always dry your TPU! Flexible filaments are "hydroscopic," meaning they soak up moisture like a sponge. Use a filament dryer before printing to prevent the "popping" and excessive stringing caused by wet material.

Hardware Preparation: The "Bypass" Setup

Some flexible filaments cannot be used through the CFS Lite and must be printed via an external spool holder.

Step 1 — Prepare the Toolhead

Remove all PTFE tubes from the toolhead.

Step 2 — Install External Spool Holder

Mount the spool holder on top of the gantry. Do not feed flexible filament through the spool holder’s pneumatic fitting.

Step 3 — Prepare a Short PTFE Guide

Mount the spool holder on top of the gantry. Do not feed flexible filament through the spool holder’s pneumatic fitting.

• Use a ~10 cm PTFE tube
• Insert it into any pneumatic port of the toolhead five-way connector

Step 4 — Load the Filament

• Remove the extruder front cover
• Open the extruder idler latch
• Insert filament into the short PTFE tube
• Once filament reaches the drive gears, close the latch
• Reinstall the extruder front cover

  

Step 5 — Finalize on Screen

• Go to Filament → External Spool Holder
• Edit filament info
• Tap Load and follow prompts

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Recommended Slicing Settings

Your software settings are just as important as your hardware.

Nozzle

Use a 0.4 mm nozzle with matching presets.

Preset Profiles

• Creality CR-TPU / HP-TPU → Use dedicated presets

  

• Third-party TPU → Use Generic TPU preset

  

Model Placement Tips

TPU strings easily, especially with frequent travel moves.

Best practice:

• Print one model at a time, OR
• Use Print by Object mode
• Avoid overcrowding the build plate

Post-Printing: Clean Removal

Remove the Model

TPU sticks very well to PEI plates. If a model has a large surface area, do not rip it off, as you might damage the plate coating.

The Method: Gently lift one corner. Spray a small amount of Isopropol Alcohol (IPA) into the gap. The alcohol breaks the surface tension, allowing the model to slide off easily.

Dealing with Stringing

Even with dry filament, you might see fine "hairs" on your model.

The Fix: Use a hair dryer on high heat or briefly pass a lighter flame over the area. The thin strings will shrivel up instantly, leaving a clean finish. (Just be careful not to melt the actual model!)

Learn more about:

SPARKX i7 FAQs: Everything You Need to Know >>

SPARKX i7 Hotend Replacement Guide >>

Creality SPARKX i7 Color Combo New Release >>