TPU Isn't That Hard — Especially with an Eryone X400

If you had to pick one 3D printing material that people love and hate at the same time, TPU would win hands down.

The ones who love it really love it — flexible, impact-resistant, great hand feel. Phone cases, drone shock absorbers, seals, gaskets… all the stuff PLA just can't do, TPU does beautifully. The ones who hate it? They've got a list too — stringing, clogging, failed prints that look like a plate of noodles. It feels like every possible thing that can go wrong has gone wrong for them at some point.

Here's the truth: TPU isn't that scary. It has a personality, sure, but once you understand how it thinks, the results are incredibly satisfying. These tips come from real testing, not theory. Hope they save you some filament.

What Makes TPU Special?

TPU (Thermoplastic Polyurethane) is basically a cross between rubber and plastic. It has the elasticity of rubber and the melt-and-print capability of plastic.

But being flexible comes at a cost — the softer the TPU, the harder it is to print. The most common grades are:

• 95A— firmer, feels like a car tire. Great for beginners.
• 85A— medium flexibility, better for shock-absorbing parts.
• 75A and below— very soft. Save these for when you've got some experience under your belt.

If it's your first time printing TPU, start with 95A. You'll thank yourself later.

Why the X400 Handles TPU So Well

One word: direct drive.

You might think "it's just a design detail" — but for TPU, it makes all the difference. Bowden setups (where the motor sits on the frame and pushes filament through a long tube) are a nightmare with flexible materials. The filament bends, expands, and clogs inside the tube. The extruder keeps turning, but nothing comes out of the nozzle — until suddenly a giant blob bursts out.

The X400's direct drive extruder sits right on top of the hotend. The path is short, straight, and direct. TPU gets pushed into the nozzle, not pulled through a tube. That's the difference between success and spaghetti.

A few other X400 features that make TPU printing easier:

• dead quiet at low speeds, no vibration artifacts on your print surface
• AC heated bed— fast heating, stable temperature, a real advantage for large TPU parts
• 3-inch touch screen— you'll be tweaking parameters a lot with TPU, and a big screen beats a tiny knob any day

Dialing In Your TPU Settings

### Temperature

TPU is actually less sensitive to temperature than PLA. Print at 200°C or 230°C — the surface quality won't look dramatically different. But higher temps mean more stringing, and lower temps mean weaker layer bonding.

Start at 220°C. For 95A TPU try 210–220°C. For 85A, go higher — 220–235°C.

### Retraction — Public Enemy #1

Write this down: keep retraction low.

TPU is soft. Too much retraction and it jams inside the hotend. The X400's direct drive already has a short filament path, so you don't need much retraction anyway.

Start with retraction off. If stringing is really bad, add just 0.5mm at 20mm/s speed.

### Print Speed

TPU doesn't like speed. You can blast PLA at 180mm/s, but with TPU, 40mm/s is already a comfortable pace. This isn't the printer's fault — TPU is soft, and if you push it too fast, the filament can't get out of the nozzle fast enough and builds up pressure in the hotend.

Start at 40mm/s. Once you're comfortable, try 50–60mm/s.

### Flow Rate

TPU compresses as it's being pushed, so the actual output is slightly less than what the slicer calculates. Start with 1.05 and check the first layer. If the surface looks under-extruded, bump it to 1.08.

### Layer Height

TPU bonds to itself way better than PLA, so you don't need tiny layer heights for strength. 0.2mm is plenty strong and keeps print times reasonable.

First Layer Tips for the X400

A good first layer makes everything easier. Here's how to nail it on the X400:

Lower Z-offset by 0.05mm. TPU needs to be slightly squished into the build plate. Too high and it won't stick. Too low and it'll get scraped off.

Bed temperature: 40–50°C. TPU doesn't need a hot bed. In fact, too much heat makes it stick too well — good luck peeling it off.

Use a glue stick. A thin layer of solid glue on the build plate (let it dry first) is the cheapest insurance policy for good first layer adhesion.

Common Problems & Fixes

Printer stops extruding mid-print — Almost always caused by too much retraction jamming the hotend. Heat it to 220°C, clear the nozzle with a cleaning needle, and turn retraction off.

Bubbles or popping sounds during printing — Wet filament. TPU absorbs moisture fast. If you hear popping, that's water vaporizing inside the nozzle. Dry at 60°C for 4–6 hours.

First layer won't stick — Check the Z-offset (might be too high). Make sure the bed is at 40–50°C. Clean the build plate with alcohol and apply fresh glue.

Warping on large prints — The X400's 400mm bed is generous, and large TPU parts can curl at the edges. Add a 6mm brim (3 layers tall) — it makes a real difference.

Final Thoughts

TPU isn't a "load and go" material, but the payoff is worth every bit of tuning. There's something special about holding a perfectly printed flexible part — a drone landing gear that bends and springs back, or a custom grip that fits your hand just right. That feeling is different from printing a hundred PLA cubes.

Start with a spool of 95A TPU. Turn off retraction. Slow down. Give it a little extra flow. The X400 gives you a solid hardware foundation — the rest is just dialing in the numbers.

One last thing: dry your filament first, and don't rush. TPU isn't hard. It just has a personality.

Have you tried printing TPU on your X400? Got any tips of your own? Drop them in the comments!