TPU 70A Printing on Bambu H2C: How to Tame Ultra-Soft Filament
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Time to read 7 min
Table of contents
Why TPU 70A Is So Hard To Print TPU 70A And 70A TPU Filament: Real Setup Tips For Bambu H2C Drying During Printing Is Not Optional For Soft TPU Support Strategy Matters More Than People Expect What The Finished TPU 70A Print Shows Common Mistakes When Printing TPU 70A A Practical TPU 70A Workflow I Would Use Closing Note
TPU 70A is one of those materials that sounds fun until you actually try to print it. It is soft, stretchy, easy to deform, and not very forgiving when the feeding path has too much drag. In my experience, TPU 70A is less about “can the printer melt it?” and more about “can the printer feed it without turning it into a noodle?”
That is why this Bambu H2C challenge is interesting. Xiaoya took on pushing a Bambu setup with very soft TPU 70A, using a smoother spool path, a Bambu-style feed assist setup, active drying during printing, and HT support material for more complex parts.
The no-BS version: TPU 70A is not beginner-friendly, but it is not impossible either. If the feeding path, drying, and support strategy are handled carefully, this kind of soft filament can produce flexible parts with serious bounce and stretch.
Why TPU 70A Is So Hard To Print
The problem with TPU 70A is not just that it is flexible. It is that it is flexible enough to fight the entire feeding system. Compared with more common TPU filaments, this softer material can stretch, compress, buckle, or bind before it ever reaches the hotend consistently.
Most users miss this part. They think the fix is only a temperature setting or a slower speed. Settings matter, but with TPU 70A, the physical path matters just as much. If the filament is being pulled from a stiff spool position, dragging through a rough angle, or fighting too much resistance, the extruder has to deal with a soft material that does not behave like PLA or PETG.
The source material describes TPU 70A as soft enough to feel almost “boneless” in the hand. That is a good way to think about it. This filament does not want to be pushed hard. It wants a smooth, low-resistance route from spool to extruder.
TPU 70A And 70A TPU Filament: Real Setup Tips For Bambu H2C
For this kind of 70A TPU filament, the setup matters before the print starts. In my experience, you want to reduce every bit of unnecessary friction because the filament is already doing its best to bend, stretch, and misbehave.
The source workflow highlights two hardware-side helpers. First, a very smooth spool holder reduces drag from the filament roll. Second, a Bambu-specific assist module helps stabilize the feeding path before the filament reaches the extruder. That combination makes sense because soft TPU needs guidance before it needs force.
This is also where a TPU feed assist upgrade can fit naturally. The Bambu TPU Feed Assist Module is positioned for flexible-filament feeding on compatible Bambu Lab printers, including H2D / H2S / H2C / P2S / P1S according to the product page. It is designed to help reduce flexible-filament issues such as buckling, binding, grinding, and uneven extrusion, but it still depends on filament dryness, profile, installation, and printer compatibility:
I would not treat any feed assist part as a magic fix. Wet filament, a clogged nozzle, wrong slicer settings, or a bad filament path can still ruin the print. But if you are already serious about printing soft TPU on a Bambu machine, a cleaner feed path is one of the first things I would look at.
Drying During Printing Is Not Optional For Soft TPU
TPU is known for absorbing moisture, and soft TPU can make that problem feel even worse. The source video specifically points to printing while drying, which is a smart move for TPU 70A because moisture can show up as bubbles, stringing, weak surfaces, or inconsistent extrusion.
Here’s the common mistake: people dry the spool once, then leave it exposed during a long print. In my experience, that can work with less sensitive materials, but TPU is less forgiving. If the print is long, or your room is humid, drying during the print gives you a more stable baseline.
That does not mean every dryer setup is automatically perfect. Spool routing, exit angle, tube drag, and enclosure placement can still affect feeding. With TPU 70A, I would rather have a boring, smooth filament path than a clever setup that adds tight bends.
Support Strategy Matters More Than People Expect
The source material mentions using HT support material for the print. That is an important detail because very soft parts can be annoying when supports are hard to remove or when the model geometry flexes during cleanup.
With TPU 70A, support strategy is not just about whether the model prints. It is also about whether the part survives post-processing without ugly scars or stretched features. In my experience, flexible parts often need more planning because the finished object can bend while you are trying to clean it.
If the model is simple, you may be able to avoid aggressive support. If it is complex, the support material and interface choices become much more important. Do not assume TPU support removal will feel like PLA support removal.
This is where Xiaoya's approach makes sense: solve feeding first, solve moisture second, then think about support quality. If you skip the first two, supports will not save the print.
What The Finished TPU 70A Print Shows
The final result shows a very soft, highly elastic part that can be squeezed, stretched, and recover its shape. That is exactly the reason people go through the pain of printing TPU 70A in the first place.
But I would be careful with expectations. The source shows a successful challenge, not a guarantee that every Bambu H2C user will get the same result on the first try. Filament brand, dryness, model geometry, support settings, feeding resistance, and machine setup can all change the outcome.
Still, the takeaway is useful: ultra-soft TPU is possible when the entire workflow is built around the material. The printer is only one part of the system. The spool path, feed assist, drying, and support plan all work together.
That is the real lesson here. If you treat TPU 70A like a normal filament, it will probably punish you. If you treat it like a soft material that needs low friction and careful handling, your odds improve a lot.
Common Mistakes When Printing TPU 70A
The first mistake is pulling TPU through a rough path. A stiff spool holder, sharp angle, or too much tube resistance can create feeding problems before the filament even reaches the extruder. Reduce drag before changing random slicer settings.
The second mistake is skipping drying. If the filament is wet, the print can show bubbles, stringing, rough surfaces, or inconsistent extrusion. With TPU 70A, I would rather over-prepare the drying setup than troubleshoot a failed soft print later.
The third mistake is assuming a feed assist module solves everything. It can help stabilize feeding, but it does not fix wet filament, poor profiles, clogged nozzles, or incorrect installation. The Call3D TPU Feed Assist Module also requires an external spool holder, and the housing/frame must be 3D printed and assembled by the user according to the product page. That is a setup project, not a plug-and-forget shortcut.
The fourth mistake is ignoring clearance and hotend-side choices. The product page notes that left versus right hotend installation can affect dual-hotend use and clearance. For Bambu H2C users, that means you should verify the installation path before assuming every configuration will fit your workflow.
A Practical TPU 70A Workflow I Would Use
If I were setting up a Bambu machine for TPU 70A, I would start with the boring mechanical checks. Make sure the filament roll turns smoothly, the path is gentle, and nothing is pulling the filament sideways. With soft material, friction is the enemy.
Next, I would dry the filament and keep it dry during the print if the job is long or the room is humid. The source video’s “print while drying” approach is the right mindset. You want stable filament behavior from start to finish.
Then I would test a small part before trusting a complex model. In my experience, soft TPU failures are easier to diagnose on a simple test than on a multi-hour print with supports. If feeding looks inconsistent, fix the path before chasing fine details.
Finally, I would add feed assist only as part of the system. A module like the Call3D Bambu TPU Feed Assist Module makes the most sense when you already understand the compatibility limits and are trying to reduce common flexible-filament feeding problems. The goal is not brute force — the goal is controlled feeding.
Is TPU 70A hard to print on a Bambu H2C?
Yes, TPU 70A is challenging because it is extremely soft and can deform, buckle, or bind in the feeding path. A smooth spool route, careful drying, and stable feed support can make the print more manageable.
Do I need a TPU feed assist module?
Not every TPU print needs one, but very soft TPU benefits from a more controlled feed path. A feed assist module can help reduce buckling, binding, grinding, and uneven extrusion, but it does not replace proper drying, correct settings, or printer-specific installation checks.
Can TPU 70A work with AMS?
For the Bambu TPU Feed Assist Module setup, the product page says AMS automatic loading and unloading are not supported. An external spool holder is required, and AMS HT TPU outlet routing may be used where applicable to help with dry routing.
What is the biggest thing to check before printing 70A TPU filament?
Check the filament path first. With 70A TPU filament, too much drag can cause problems quickly. Keep the spool movement smooth, avoid tight bends, dry the material, and test with a small model before committing to a complex print.
Closing Note
TPU 70A is not the kind of filament I would casually throw into a printer and expect perfect results. It needs a smoother path, better drying discipline, and more patience than harder TPU. But when the setup is right, the payoff is obvious: soft, elastic parts that normal rigid materials cannot match.
For Bambu H2C users, the main lesson is simple. Do not fight soft TPU with force. Guide it, dry it, support it correctly, and give the filament the cleanest route you can. That is how TPU 70A goes from “printing nightmare” to a realistic challenge.
