Updated 2026-10-30
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Quick answer: Most beginners should start with 95A TPU, the stiffer and easier grade, ideally on a direct-drive printer. In our planning example, a 40 g phone-stand bumper costs about $1.20 in TPU vs $0.80 in PLA and takes roughly twice as long to print. Print slowly and keep the spool dry.
When TPU is the Right Flex Material
TPU (Thermoplastic Polyurethane) is the go-to flexible filament for beginners due to its balance of elasticity, durability, and printability. It's ideal for parts that need to bend, stretch, or absorb impact, such as phone cases, flexible hinges, and wearable prototypes. Unlike rigid materials like PLA or ABS, TPU can deform without breaking, making it perfect for functional parts. However, it's not the best choice for high-stress applications like structural beams or load-bearing components, where rigidity is essential. TPU also performs poorly in extreme temperatures, so avoid using it for parts exposed to prolonged heat or cold. For beginners, TPU is a great starting point because it's easier to print than other flexible filaments like TPE (Thermoplastic Elastomer) or high-shore TPU variants. Always confirm your printer's compatibility before purchasing.
Is Your Printer Ready: Direct Drive vs Bowden
TPU requires a printer with a direct-drive extruder to ensure proper feeding and minimize stringing. Direct-drive extruders have the motor mounted directly on the extruder body, allowing for precise control over filament flow. This is critical for TPU, which is more prone to clogging and requires lower retraction settings. If your printer uses a Bowden extruder (where the motor is separate from the extruder body), it can still work with TPU but requires adjustments. Lower print speeds (e.g., 20-30 mm/s instead of 50-60 mm/s for PLA) and minimal retraction (0.5-1.0 mm) are essential. Some Bowden printers may struggle with TPU due to the increased friction and need for precise tensioning. Always test a small print first to confirm compatibility.
TPU Classes: The Criteria Table
TPU is categorized by Shore hardness, which measures flexibility. Lower numbers (e.g., 85A) indicate softer, more elastic material, while higher numbers (e.g., 95A) are stiffer and more durable. Below is a planning example to help choose the right class:
| Class | Best For | Watch Out For | Example Planning Numbers |
|---|---|---|---|
| 85A | Flexible parts (e.g., hinges) | May require more careful printing | 3.0 cents/gram, 2x slower than PLA |
| 95A | Durable parts (e.g., phone cases) | Stiffer, harder to print | 3.0 cents/gram, 2x slower than PLA |
For beginners, 95A is often recommended because it's easier to print than 85A, which can be more prone to warping or stringing. However, 85A is better for parts requiring extreme flexibility. Always check your printer's capabilities and the part's requirements before selecting a class.
Speed, Retraction, and Drying
TPU prints significantly slower than rigid filaments like PLA. A typical PLA print at 50 mm/s may take 1.5 hours, but TPU will require 3 hours for the same part. Use a print speed of 20-30 mm/s to avoid clogging or under-extrusion. Retraction settings should be 0.5-1.0 mm to prevent stringing, as TPU is more prone to oozing.
Drying is also critical. TPU is hygroscopic, meaning it absorbs moisture from the air, which can cause bubbling, poor layer adhesion, and clogging. Always use a dry spool or store TPU in a desiccant container. If your spool is not dry, consider using a filament dryer (e.g., a 3D printer-specific desiccator) before printing.
Cost Per Print vs PLA
TPU is generally more expensive than PLA, with prices ranging from 2.5-4.0 cents per gram compared to PLA's 1.5-2.5 cents per gram. For a 40g phone-stand bumper, TPU costs $1.20 (40g x 3.0 cents/gram), while PLA costs $0.80 (40g x 2.0 cents/gram). The difference is 40 cents, which can add up for multiple prints. However, TPU's durability and flexibility often justify the cost for functional parts.
Print time also affects cost. A 1.5-hour PLA print becomes 3 hours for TPU, increasing the opportunity cost of time. Use a filament cost calculator (see link) to compare total costs for your specific project.
How to Pick by Part Type
The type of part you're printing determines the right TPU class and settings. For phone cases, 95A is ideal because it's stiff enough to protect the phone but still flexible enough to fit over the device. For flexible hinges, 85A is better due to its elasticity.
If printing wearable parts (e.g., bracelets), ensure the TPU is dry and use a 0.4 mm brass nozzle for smooth extrusion. Avoid using TPU for thin, intricate parts unless your printer has a direct-drive extruder and can handle low speeds. Always test a small sample before printing the full part.
Worked Example: Cost and Time for a Phone-stand Bumper
Let's compare a 40g phone-stand bumper printed in TPU (95A) vs PLA:
- TPU cost per gram: 3.0 cents/gram (planning assumption).
- PLA cost per gram: 2.0 cents/gram (planning assumption).
- TPU weight: 40g.
- PLA weight: 40g.
- TPU cost: 40g x 3.0 cents/gram = 120 cents ($1.20).
- PLA cost: 40g x 2.0 cents/gram = 80 cents ($0.80).
- Cost difference: $1.20 - $0.80 = $0.40.
Print time:
- PLA print speed: 50 mm/s.
- TPU print speed: 25 mm/s (planning assumption).
- PLA print time: 1.5 hours.
- TPU print time: 1.5 hours x (50 mm/s / 25 mm/s) = 3.0 hours.
Final check: The TPU part costs $0.40 more and takes 1.5 hours longer to print than PLA. Use a filament cost calculator to adjust for your specific project.
Common Mistakes
- Assuming all TPU is the same: Shore hardness and printability vary significantly between classes.
- Ignoring printer readiness: Bowden extruders may struggle with TPU without adjustments.
- Not drying the spool: Moisture can cause clogging and poor layer adhesion.
- Using high retraction settings: TPU is prone to stringing, so keep retraction to 0.5-1.0 mm.
- Printing too fast: TPU requires slower speeds (20-30 mm/s) to avoid under-extrusion.
Who This Is Not For
This guide is not for users requiring medical-grade filaments, high-strength materials (e.g., for engineering parts), or printers incompatible with TPU (e.g., those with poorly calibrated Bowden extruders). It also avoids health claims or wearable device recommendations, as TPU's safety for prolonged skin contact is not covered here.
FAQ
Q: What Shore hardness is best for beginners? A: 95A is recommended for its balance of stiffness and printability, though 85A is better for highly flexible parts.
Q: Can I use TPU with a Bowden extruder? A: Yes, but reduce print speed to 20-30 mm/s and retraction to 0.5-1.0 mm.
Q: How do I dry TPU? A: Store TPU in a desiccant container or use a filament dryer (e.g., a 3D printer-specific desiccator).
Q: Is TPU more expensive than PLA? A: Yes, TPU costs 2.5-4.0 cents/gram vs PLA's 1.5-2.5 cents/gram, but the cost depends on the part's weight.
Q: How do I choose between 85A and 95A? A: 85A is for highly flexible parts (e.g., hinges), while 95A is for durable parts (e.g., phone cases).
Use the filament cost calculator to compare TPU, PLA, and other materials for your next project. Input your part's weight, filament type, and printer settings to get instant cost and time estimates.
Related guides
- PLA vs PETG vs TPU Filament for Beginners
- Filament Cost Per Print Calculator for Beginners
- Print Time Estimation for Different Filament Types
- Filament Cost Calculator for 3D Printing Beginners
- Spool Cost Per Print Estimation for Beginners
Questions about this guide? Email hello@charlandandco.com.