# Specific 3D Printers, Scanners, & Hardware > QiDi 3D Printer Forum >  Qidi X-Max jamming with Ninjaflex Ninjatek TPU

## GotCoffee88

I recently purchased a Qidi X-Max, and the first print with PLA went flawlessly. It's an amazing printer, considering the price.


However, I tried to jump over to Ninjaflex NinjaTek (50-55A durometer) and it repeatedly jams within 1-2 hours of printing. I've tried raising the hot end to 250C and dropping speeds below 25 mm/s, but I still can't stop it from jamming. I'm guessing that pressure is building up in the head, but I don't know how to prevent it. Every time, it skips the drive gear and grinds inside the single-gear extruder.


Any suggestions on what to do about it?

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## fred_dot_u

I've noticed with my X-Max that I can accidentally re-direct the PLA filament in such a manner that it does not exit the nozzle and instead exits to the rear of the assembly. This leads me to believe that there's an excessive gap etween the gear and pinch roller and the heat sink/hot end assembly. I've recently worked on a Robo3D R1+ conversion from stock to E3Dv6 which included a short length of PTFE tubing. The end of the tubing has to be chamfered to fit more closely to the exit of the pinch roller and hobbed gear. 

I've not taken apart my hot end assembly to examine the corresponding location on the X-Max, but I suspect that the filament is not getting pushed into the hot end and is instead buckling and jamming in the manner you describe.

On a side note, did you find any form of manual on the USB drive that ships with the printer. I purchased my printer new and came with nothing of the sort. The manufacturer provided me with the S3D configuration file, but if there's a manual on the disk, I'd love to see it. The manufacturer's web site is sorely lacking in that respect.

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## curious aardvark

print flexibles slower - NO slower than that :-)
15-20mm/s
Possibly evem down to 10mm/s for the really bendy stuff/. On the positive side you don't actually need to heat the porintbed up and the first layer can go down at 100% print speed - which helps for larger prints. 

It might also be worth taking the extruder apart and seeing if you can insert a short length of ptfe to make sure the filament can't escape the path.
All my extruders - bar the sapphire pro - have been modified with ptfe tube. Unfortunately the bmg extruder on the sapphire pro, can';t be modified and is absolutely crap for flexibles, they manage to escape sideways. It should not be technically po9ssible - but nobodsy tells the filament things like that :-)
And if it can escape - it will, a bit like sheep :-)

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## fred_dot_u

@curious aardvark, the comma missing after "NO" seriously changes the context.

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## tron

I have an x-plus. When I ran into a similar  problem with NinjaFlex, QiDi’s support told me to bypass the filament feeding tube mounted on the printer and feed the filament directly into the extruder from the top to reduce the pull on the filament. That coupled with upgrading the feed roller with a ball bearing mechanism worked for me. I can now print with NinjaFlex without jamming.

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## fred_dot_u

tell us more about the ball bearing mechanism? do you have photos and a reference for the part? If the feed roller wasn't a ball bearing type, was it merely a bushing mounted roller?

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## tron

This is what I’m referring to:
https://www.thingiverse.com/thing:4277874

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## fred_dot_u

oh shucks, that's not what I expected. I had some other bearings left over from a project and replaced the entire rod/shaft with a new one. The roller spins so freely that a full spool unrolls and tangles, so I had to switch back to the original. I would not expect that is a critical factor, but if it improves TPU printing, I have it in reserve. I thought it was a reference to the pinch wheel on the extruder.

I think it's back to the gap between the feed mechanism and even more likely the too-high speed for such soft material.

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## tron

You may want to look into the extruder upgrade shown below. I’m in the process of upgrading mine so I can’t personally vouch for it at this point but others have said this upgrade helps with printing flex materials thanks to the two-gear extruder.

https://www.thingiverse.com/thing:3994628

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## fred_dot_u

That's an amazingly comprehensive (and complex) upgrade for the printer. My Sigma 16 uses Bondtech geared extruders and I know how well they work, but this upgrade sort of scares me!

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## tron

Well, I’ll let you know how scary it actually is once I receive all the parts and perform the upgrade. ????

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## fred_dot_u

Great! Take tons of photos!

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## tcinsatx

Thanks, Tron, for this info. I just bought a Qidi X-Max and am looking forward to printing with flexible filament.

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