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Worst filament ever

Yeah it does not look round...

I had many problems lately with my extruder.
First I broke its PTFE tube because I printed with extruder nozzle too close to the bed.

When I replaced the PTFE tube, I have been supposed to prepare the PTFE tube like this:

I drilled with 4.5mm drill bit too much. with my new filament the extruder is very unreliable.

I think with this filament the extruder is operating beyond its limit.
I bought 50kg of it in 5kg coil form, like this:

Here it's a comparison photo between my old (blue) and new(white) filament:

I called my teddy bear to help measuring it:-)

The micrometer precision is 0.002 mm by the datasheet.

The cross-section of the new filament:

Looks like it has more an egg form then an ellipse:-(

Here is what Teddy bear measured on the old filament:

And a 90 degrees turn of the filament:

Its is pretty round in my opinion.

And now the new filament:

And the 90 degrees turn:

Yeah, I could not believe in my eyes either. The difference between 3.5 and 2.7mm diameter is a huge.
Working with this filament is not easy, I do believe i need a more reliable extruder then the stock Rapman's extruder.

I need to crack this nut, because I have 50kg of this filament...

Comments (6) Trackbacks (2)
  1. Where did you buy the filament from? name and shame.

  2. Looks like we have the same filament. I had issues with the backflow in the extruder due to the oval shape. I started pulling it through holes in a metal plate from 3.5 to 2.9mm in 0.1mm steps. Its quite labor intensive but at least I don’t have to throw it away.

  3. Giles: I dont blame the guy, from who I have bought it. He never said it will work, he doesnt have a working machine. In plus, Im still waiting the second half of the shipment to arrive;-)
    The filament originally is from a chinese factory. (I dont know exactly their names).

    Markus: Im able to print with it, just it is not reliable. It gets blocked after 1.5hours. And starting a new print has more problems.

    Im redesigning the extruder, because it could be made to work. (more of it later, probably next week).

    In fact on the first picture, the two y-moto-brackets are printed using this filament.

    If you help pushing the filament by hand, it works;-) Just it is a lot of work.

  4. I was also able to print, but always got some random blocks. It always blocked after some time, when the extruder thermal insulation was getting warm. I’m pretty sure it was because of the oval shape of the filament, some abs could flow back to quite cold extruder regions, where it got stuck.
    The other problem is, you can’t control the backflow. And during a backflow the extruder will extrude a lot less. So print quality suffers anyway (I was printing drive-pulleys).
    Also my filament isn’t constant iregular. I got anything from 2.6×3.2 to 2.8×3.6mm.
    I just had enough of removing stuck filament, and I still think its easier for me to fix the filament than to build a super robust extruder.
    But hopefully you succeed where I failed (50kg is a LOT).

  5. Using high quality purpose machined PTFE tube solves the stucking problem. I can easily pull it back (while it is hot) the filament. The problem, that the extruder’s threading rod cant grip enough into the plastic. Due to its oval shape.

    If you have problems with your PTFE tube, I have just got machined enough PTFE tube (for Rapman’s extruder).
    It is made from a 8mm diameter PTFE rod with a lathe, and it has a completely non transparent white color.

    It is available for sale. I sell it 3EUR/piece, which is a pretty good deal I think.


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