Problem printing with PLA Flex

I have been trying to print PLA Flex, and I am getting bit of trouble.
I tried a number of things so far in cura:

  • disable retraction

  • speed down to 15mm/s

  • temp 225 deg

  • cook the filament for 6h at 50 deg celcius

  • increase flow to 120%

  • left flow to 100%

  • layer set to 0.1mm

  • the first layer is pretty good
    However then the result is not great, it is not smooth.
    The most effective improvement was increasing the flow.
    At 100%, the filament lines are broken in small blobs. Usually that typically because of moisture.

Calibration wise, I used the same one as for PLA which works great + 0.05mm

Any else I could try to get as good results as with PLA ….with normal PLA, I get outstanding results…

Have you tried drying the filament? Often factories can accidentally ship wet filament, even in a vacuum bag with desiccant.

Not sure what’s going on with the top either - underextrusion, or the temp is too high, or maybe it’s very wet, or a partial clog.

@gpt1plon I’ve never used PLA Flex before, and really hadn’t heard about it until now, so I had to do some research to make sure that my first thoughts were correct. If you look very closely, you’ll see shinny melted areas that have no form. That typically means that the temperature is too high, which matches what I’ve found. That also explains the holes and missing patches, as the temperature is at a level where it is beginning to coagulate.

Try 215°C and see how it turns out. If that’s no good enough, try dropping the temperature by 5°C for each subsequent test until you find a good temperature to print at. Alternatively, you could print a temperature tower, and/or follow the directions at Temperature Tuning. I couldn’t find any references to its hygroscopy, and I don’t really see any steam explosions, so I don’t know if it is something that you need to dry before using.

Best of luck!

I guess its printed too hot too.
Flex from renkforce used to print with 190° for example.

I’ve got some eSUN Flex (PLA based TPU? 87A) I’m putting up shortly, I’ll let you know how I go!

I’ve been dialing in PA (Nylon) seem to have it sorted.

PLA & PTEG seem pretty easy although I’m not sure how good the SM stock filament is?

Full metal hot end parts are on order and then I’ll be dialling in some Wood filled and PA-CF (also got 0.6 nozzle in case of clogging)


Snapmaker filament is unreliable in quality. Some people have had no problems with it; others have gotten spools that are practically unusable. Snapmaker sources their filament from third parties rather than manufacturing it themselves, and not all of their sources have good QA. However, there have been fewer complaints about the newer spools (the legendary bad ones were mostly shipped out with the Kickstarter rewards), so you may get lucky.

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I did a PETG print… all good, nice result….

Back to flex PLA, I am doing a temp tower, starting at 195. That’s not pretty so far.

Maybe that’s just crapy filament. Better use TPU then!

You should try changing hotends. There’s a spare in the toolkit. When you pull that one out make sure the thermistor is at the bottom of the well. It looks like it’s not accurately measuring temperatures and is wayyyyyy too hot.

Worlds most expensive test draws for some crap model off Cults…

eSUN Flex 87A printing so far so good! :slightly_smiling_face:

(Left) eSUN PA (Nylon) 3 attempts to get acceptable :+1:

(Right) SM PTEG :man_facepalming:


Well, if there was a temp issue, I couldn’t print PLA, ABS or PETG successfully?
I just can’t get anything out of that filament!

You make a convincing point. What could be causing the blobs on the top then… And usually excessive stringing partially indicates too hot.

Try turning cooling fan down a touch?

With PA I went down to 0% first 4 layers then only 40%

My settings for Flex so far is generic TPU 95A in Cura
0% first 2 layers then 80%
Retract on
30% infill


Not bad for a first run…

Material would not auto load, (bunched up in the module) I had to work it through the hot end by hand or light/moderate pressure on the cover mechanism. I can only imagine softer materials would be more difficult to load!

Pull through with an enclosure was like a bungee cord :man_facepalming: Could do with smoother system. I guess that’s up to us?

Artefacts in the print I can narrow down to infill speed at times inside the walls was to fast so I’m going to print another with infill maxed to 25mm/s as opposed to 50mm/s

Surfaces are smooth and no delamination feels strong.

Only adjustments to my above baseline will be slow the infill and slight drop in cooling fan :+1:

And after all that I just realised my material is actually TPU and not PLA based which is what it was marketed to me as…

I do hope there is a little bit of use in my ramblings :joy:


If you’re not already using one, this thread Printing TPU with A250 (or any SM 2.0) - #37 by stevilg links to files for a small adapter you can print (or CNC). It fills up the slack space inside the print head so that flex filament doesn’t have anywhere to bunch up.

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