The Appeal of Bendable Prints
The goal is straightforward: to create truly flexible, rubber-like parts that you can squeeze, bend, and twist. There's something really satisfying about holding a perfectly printed, highly flexible part that feels more like a store-bought product than a 3D print. But this appeal often comes with worry. We've all seen the pictures or dealt with it ourselves: a tangled mess of spaghetti-like filament wrapped around an extruder gear, turning what looked like a promising print into hours of annoying cleanup.
This brings us to the main question for anyone trying materials beyond standard rigid filaments: Is printing 85A TPU really that much harder than printing 95A? The numbers seem close, but what actually happens during printing can be completely different. This guide provides a practical, experience-based comparison of TPU 95A vs TPU 85A. We will move beyond theory to give you the useful advice needed to master both materials, or to choose the right one for your skill level and equipment in 2025.
Understanding the Numbers
To understand the printing challenges, we first need to explain the numbers. The "95A" and "85A" ratings refer to the material's Shore Hardness, a standard way to measure the softness of flexible materials.
The Shore A Scale
The Shore Durometer scale measures a material's resistance to being pressed in. For our purposes, it's a simple measure of softness. The lower the number, the softer and more flexible the material. To put these numbers into real-world terms, think of these common objects:
- 95A TPU: This feels like a skateboard wheel or the hard rubber tire on a shopping cart. It is firm, with noticeable give when you press hard, but it mostly holds its shape. It's flexible, but not truly "squishy."
- 85A TPU: This is closer to the sole of a running shoe or a classic pink rubber pencil eraser. It is noticeably soft to the touch and easy to squeeze. This is the "squishy" feel many people want.
A Ten-Point Difference
On paper, a ten-point drop from 95A to 85A might seem small. In the world of 3D printing, it represents a huge jump in difficulty. The relationship between Shore hardness and how easy it is to print is not straight-line. That small number difference translates to a major change in how the filament behaves as it's pushed through the extruder and hotend. A filament that is just a little softer requires a completely different approach to printing, as it is far more likely to fail under the mechanical stresses of the printing process.
The Science Behind Failure
The main challenge of printing softer TPU can be summed up in one idea: the "wet noodle effect." Imagine trying to push a cooked spaghetti noodle through a small tube. It will definitely bend and buckle. The same principle applies to soft filament. The extruder gear is trying to push this highly flexible strand into the melt zone, and any resistance can cause it to fold and jam.
This leads to several key mechanical problems that are far more serious with 85A than with 95A.
- Filament Buckling: This is the main failure mode. The filament is pushed by the drive gear toward the hotend. If there is any open space in the filament path—even a millimeter or two—the soft filament, under pressure, will bend into that gap instead of moving forward into the nozzle. This causes an immediate jam.
- Extruder Grip Issues: The drive gears that grip the filament face a problem. If the tension is too loose, the gears will slip on the soft, slick surface of the TPU, leading to inconsistent feeding and under-extrusion. If the tension is too tight, the gears will deform or flatten the filament, changing its shape and causing it to jam in the tight spaces of the heat break or nozzle.
- Elastic Behavior and Pressure Buildup: Soft 85A filament acts like a spring within the Bowden tube or even in the short path of a direct drive extruder. As the extruder pushes, the filament compresses. When the extruder stops, the filament expands. This makes retraction almost completely useless. The stored pressure continues to force filament out of the nozzle, leading to severe oozing and stringing. The compression and stretching also mean the flow of plastic is not instant, making precise material placement a big challenge.
Head-to-Head Comparison
Here we break down the practical differences you will encounter when printing TPU 95A vs TPU 85A, from hardware needs to the final slicer settings.
Hardware Requirements
Your printer's hardware is the single most important factor in determining your success with soft flexible materials.
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For 95A TPU (The Accessible Flexible):
- Extruder: A direct drive extruder is highly recommended for a consistent and trouble-free experience. The short, controlled path minimizes the chance of buckling. However, a well-tuned Bowden setup can work with 95A. This requires slow speeds, minimal retraction, and often a high-quality tube with tight internal tolerances. It is challenging but possible.
- Filament Path: A controlled path from the gear to the hotend is helpful, but minor gaps may be tolerated with careful tuning.
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For 85A TPU (The Expert's Flexible):
- Extruder: A direct drive extruder is absolutely necessary. Success depends on having the shortest, most controlled path possible between the drive gear and the melt zone. Any system with a significant gap is almost guaranteed to fail.
- Filament Path: A fully controlled filament path is absolutely critical. This means there is no room for the filament to go anywhere but straight into the heat break. Any unguided space is a potential point of failure where the "wet noodle" will buckle.
Preparation is Everything
All TPU filaments absorb moisture from the air. This moisture turns to steam in the hotend, causing a host of print quality problems.
- 95A: This material is moderately forgiving. You might get away with printing from a spool that's been out for a day or two, but drying is always best practice. If you experience stringing or popping sounds, drying the filament is the first and most effective solution.
- 85A: Drying is absolutely critical and non-negotiable. Attempting to print even slightly damp 85A TPU is a recipe for complete failure. You will hear constant popping and hissing from the nozzle as steam escapes, see extreme stringing that looks like spiderwebs, and the final part will have a terrible surface finish and poor layer bonding, making it brittle. Using a dedicated filament dryer as a standard part of your workflow is a requirement for success with 85A.
Slicer Settings Guide
Your slicer settings are where you control the physics of the printing process. The approach for 85A is fundamentally different from 95A, focusing on minimizing pressure and managing ooze rather than trying to eliminate it with retraction.
| Slicer Setting | 95A TPU (Baseline Settings) | 85A TPU (Advanced Settings) | Reason for the Change |
|---|---|---|---|
| Print Speed | 25-40 mm/s | 15-25 mm/s | Slower speed reduces back-pressure in the nozzle and prevents the soft filament from buckling under the compression force from the extruder. |
| Retraction Distance | 0.8-2.0 mm (Direct Drive) | 0.0-0.5 mm (Or Disabled) | The extreme stretchiness of 85A makes retraction useless. The filament just stretches instead of pulling back, making it a primary cause of jams. It is better to manage ooze with other settings. |
| Retraction Speed | 20-30 mm/s | 10-20 mm/s (if enabled) | Slow, gentle movements are necessary to prevent the drive gear from grinding away the soft filament or stretching it, which can cause a jam on the un-retraction move. |
| Print Temperature | 220-240°C (Follow mfg. range) | Often +5-10°C higher than 95A | A slightly higher temperature lowers the thickness of the molten plastic, allowing it to flow more easily with less force required from the extruder. This further reduces the risk of buckling. |
| Extrusion/Flow % | Calibrate (often ~105%) | Calibrate carefully (often 105-115%) | Softer filament can be slightly compressed by the drive gears. A higher flow rate is often needed to compensate for this volume change and prevent chronic under-extrusion. |
| Cooling Fan Speed | 20-50% after first layers | 0-30% after first layers | TPU has excellent natural layer bonding. Too much cooling, especially at the very slow print speeds required for 85A, can weaken layer bonds. Minimal cooling is usually sufficient. |
| Travel Speed | 100-150 mm/s | >150 mm/s | With retraction disabled or minimized, the strategy is to move the nozzle between printed sections as quickly as possible. This minimizes the time the nozzle has to sit still and ooze molten plastic. |
Troubleshooting Common Failures
Even with perfect preparation, you will likely encounter issues. Here is how to diagnose and fix the most common problems.
Failure 1: Jam in Extruder
- More likely with: 85A, by a large margin. This is the classic buckling failure.
- Fix: The first and most important step is to immediately slow down your print speed. This is the number one cause of excess back-pressure. Next, inspect your filament path for any open gaps and find a way to eliminate them. Finally, reduce your retraction distance to near-zero or disable it completely, as the push-pull motion is a major source of jams.
Failure 2: Severe Stringing
- More likely with: 85A, primarily because you cannot use effective retraction.
- Fix: First, ensure your filament is completely dry. Even a small amount of moisture will cause oozing that looks like stringing. Run a temperature tower to find the lowest possible temperature that still provides good layer bonding; lower temps mean less ooze. Increase your travel speed to the maximum your printer can handle. Finally, explore advanced slicer settings like "Coasting," which stops extruding just before a travel move, and "Wipe," which moves the nozzle over the print to clean off any excess plastic.
Failure 3: Inconsistent Extrusion
- More likely with: 85A. This shows up as gaps in walls or a rough, uneven texture.
- Fix: Check your extruder gear tension. It must be just tight enough to grip the filament without deforming it. You should be able to see very light teeth marks, but the filament should not be flattened. Carefully calibrate your flow rate (extrusion multiplier) for the specific spool of 85A filament. It often requires a higher value than you expect. And as always, when in doubt, slow down the print speed.
The Verdict: Measuring the Jump
So, just how much harder is it? Let's measure the jump in difficulty.
- From PLA to 95A TPU: This is a moderate step up. It requires a fundamental shift in mindset toward "slow and steady wins the race." You must learn to tune retraction and accept slower print speeds. It's an excellent introduction to the world of flexible filaments and is achievable on a wide range of modern printers.
- From 95A to 85A TPU: This is a significant leap into advanced territory. This jump moves beyond simple slicer settings and becomes a challenge of hardware optimization and process discipline. Success is heavily dependent on having the right equipment—specifically a high-quality, fully controlled direct drive extruder. It is far less forgiving of any shortcuts in filament drying, speed, or calibration.
To use an analogy, printing with 95A TPU is like learning to drive a car with a manual transmission. It takes some practice to get the feel for the clutch and shifter, but it's a common skill to learn. Printing with 85A TPU is like being handed the keys to a classic race car with a sensitive clutch, no power steering, and a temperamental engine. It demands more skill, constant attention, and a deep understanding of how the system works.
Print with Purpose
In the TPU 95A vs TPU 85A debate, the difference in printing difficulty is substantial. Your choice should be driven by your application and your appetite for a challenge.
95A TPU is the versatile, reliable workhorse. It's perfect for functional parts that need durability and moderate flexibility, like custom gaskets, vibration dampeners, and protective cases. It strikes an excellent balance between flexibility and printability.
85A TPU is a specialist material. It should be chosen when the primary design goal is maximum softness and "squishiness"—for things like ultra-flexible grips, wearable items, or soft robotic components.
Do not be afraid of the 85A challenge, but go into it with open eyes and realistic expectations. Mastering it is a mark of a skilled, patient, and methodical 3D printing operator. With the knowledge from this guide, you are now well-equipped to tackle the flexible filament challenge and choose the right material for your projects in 2025.