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Inconsistent thickness after 30 metres



I'm currently working on finding the best setting profiles for different ratios of virgin PLA granules and recycled PLA waste material.

If found some decent settings that seem to work. However, after around 30-35 metres of extruded filament the thickness starts to fluctuate a lot, even though I didn't change any settings in the extrusion process and also the surrounding didn't change. There is also enough material in the hopper. This happened with the 50-50 mix and also with the 100 % recycled material. I've tried adjusting the spooling tension and the extrusion speed but that also didn't help in the long-term. I didn't want to change any temperature settings as they worked for the first 30 metres. 

Any ideas why this is happening or how I can solve that problem?

Thanks in advance!


Topic starter Posted : 17/04/2021 8:16 am

The problem has nothing to do with the settings on the extruder, the material does not flow evenly. Shred the recycling material a little smaller and try again.



Posted : 17/04/2021 8:28 am


Thanks for the tip. I will try it out and hopefully it'll work!

Topic starter Posted : 17/04/2021 8:44 am
Member Admin

Hello @arpikkarainen and @gerd

Thank you both for sharing your experience 😉 

Indeed, when working with shredded flakes, inconsistent feeding is a common issue, as shown in the attached picture.

Shredding the particles smaller might not fix the issue, but shredding the batch of flakes again shouldn't take long ; that will increase the size homogeneity, and that can stabilize the flow a little.

It is possible that the settings are not optimal. If you send me a short 20s video of the output coming out of the nozzle, I might be able to identify the type of issue. (you can do so as an attachment on the Forum, or to if it is too big).

Conclusion :

- can you please keep an eye on the feeding, and perhaps send me a short vid of what happens in the hopper ?
- can you please show me the output with a short vid ? If possible, once in the first 30min (when everything is 'fine') and once after (when the fluctuation starts)

There are many factors to take into account here, but I am sure we can narrow our diagnosis down to the core problem very soon.

If you have any questions, please let me know !


Best regards,

Posted : 20/04/2021 1:02 pm