Creality CR-10 Ninjaflex

First, a correction this page owes you: there is no such machine as a “Creality CR-10 NinjaFlex.” The old version of this article reviewed one anyway, complete with a direct-drive extruder, dual Z axis, enclosed chamber and built-in bed leveling — every one of which is the opposite of a stock CR-10. NinjaFlex is not a printer at all. It is a filament: a soft, rubber-like TPU made by Fenner Drives, famous for being one of the most flexible — and most demanding — materials a desktop printer can run.

So the real question this page should answer is the one owners actually ask: can a CR-10 print it? The short answer is yes, within limits — and the limits are set by the CR-10’s Bowden tube.

Why flexible filament fights a Bowden printer

A stock CR-10 pushes filament from a frame-mounted extruder through a long PTFE tube to the hotend. Stiff PLA barely notices. Soft TPU behaves like pushing a rope: under pressure it buckles and coils inside the tube and extruder path instead of advancing, and the softer the filament (NinjaFlex, at around 85A shore hardness, is about as soft as FDM filament gets), the worse it behaves. Every setting below exists to reduce that pressure and give the filament nowhere to escape.

Settings that give a stock CR-10 its best chance

Work within these conservative ranges, and change one thing at a time:

• Print slowly — really slowly. Around 20–30 mm/s, evenly, including walls and top layers. Speed spikes are pressure spikes, and pressure is what buckles the filament.
• Retraction: minimal or off. Every retract/deretract cycle pumps soft filament back and forth through the tube. Start with retraction disabled; if stringing is unbearable, add distance back in very small steps (fractions of a millimetre) at a slow retraction speed.
• Feed path as straight and constrained as possible. This is where a Capricorn-style tube (tighter internal tolerance than the stock tube) genuinely helps: less room sideways means less room to buckle. Make sure the filament path into the extruder has no unsupported gap for the filament to fold into.
• Temperatures in NinjaFlex’s normal range — roughly 225–245 °C at the nozzle, with the bed warm (around 50–60 °C) rather than hot; our bed adhesion guide covers TPU first layers, which are usually forgiving if the first layer is slow.
• Cooling moderate, not maximum. TPU layer bonding suffers when the fan blasts every layer; part cooling around half, after the first layers, is a sensible starting point. The profiles logic in our Cura settings guide explains how to build a separate material profile so these settings do not overwrite your PLA setup.

Start with a small, simple test part — a short, thick-walled object — before committing to a long print. Flexible filament failures are usually slow tangles, not dramatic ones, and a twenty-minute test tells you more than any settings list.

The honest limit — and the real fix

There is a point where tuning stops helping: very soft TPU at anything beyond slow, gentle geometries will keep defeating a long Bowden path. That is not a CR-10 defect; it is physics, and it is why flexible-filament specialists use direct drive — the extruder sits on the print head, the filament path shrinks to a few centimetres, and buckling has nowhere to happen. If NinjaFlex-class materials become your main work rather than an experiment, a direct-drive conversion is the upgrade that actually changes the answer (and it adds gantry weight — the mechanical side of that trade is covered in our CR-10 dual Z guide).

Firmer TPUs (95A class) are a different story — a well-set-up stock CR-10 handles those far more comfortably, and they cover more real uses (gaskets, grips, bumpers) than the ultra-soft grades.

Frequently asked questions

Is the CR-10 NinjaFlex a real Creality printer?

No. No such model exists. NinjaFlex is a flexible TPU filament brand. The “printer” described in some old articles — direct drive, dual Z, enclosed — was invented; a stock CR-10 is an open-frame, Bowden, single-Z machine.

Can a completely stock CR-10 print NinjaFlex?

It can, slowly and carefully, with the settings above — expect a learning curve and occasional tangled feeds. A tighter-tolerance Bowden tube improves the odds. For regular NinjaFlex printing, direct drive is the proper fix.

What is the best speed for NinjaFlex on a CR-10?

Slow and even: around 20–30 mm/s is the working range most Bowden setups tolerate. Faster printing raises feed pressure and is the most common cause of buckling and jams.

Why does the filament tangle in the extruder instead of feeding?

Because soft filament under pressure takes any sideways escape route — a gap at the extruder inlet, or slack inside an oversize tube. Constraining the path (tight-tolerance tube, no unsupported gaps) and lowering pressure (slow speed, minimal retraction) are the two levers you have.