Defective PTFE Tube - unable to load filament  

Re: Defective PTFE Tube - unable to load filament

Hi Markus,

the Ptfe does indeed look split.

but that shouldn't cause a blockage to the filament, unless a broken piece has got into the filament feed hole down the middle...

could you try doing some 'Atomic' pulls, to clear the filament path

https://shop.prusa3d.com/forum/prusa-i3-kit-building-calibrating-first-print-main-f6/atomic-method-cleaning-take-off-the-extruder-cover-t2702.html#p21183

regards Joan

Re: Defective PTFE Tube - unable to load filament

the PTFE Tube is an expendable item, it will always wera or deform over a period of time,

this will depend upon many factors, heat, filament abrasive nature, ptfe quality
etc.

please see the ptfe change thread here https://shop.prusa3d.com/forum/prusa-i3-kit-building-calibrating-first-print-main-f6/instructions-for-replacing-ptfe-tube-t2434.html#p19702

also note the ends of the PTFE should be shaped before use...

regards Joan

Re: Defective PTFE Tube - unable to load filament

Hi Markus,

the Ptfe does indeed look split.
but that shouldn't cause a blockage to the filament, unless a broken piece has got into the filament feed hole down the middle...
could you try doing some 'Atomic' pulls, to clear the filament path

https://shop.prusa3d.com/forum/prusa-i3-kit-building-calibrating-first-print-main-f6/atomic-method-cleaning-take-off-the-extruder-cover-t2702.html#p21183

regards Joan

Hi Joan,

thanks for your reply. I will try to do some Atomic pulls when I am back home from work.
What confuses me is, that the prints turn out to be just fine, as soon as the filament is loaded, so I am unsure if there is really a blocking issue somewhere.

I will report back!

Cheers,
Markus

Re: Defective PTFE Tube - unable to load filament

the PTFE Tube is an expendable item, it will always wera or deform over a period of time,
also note the ends of the PTFE should be shaped before use...

This is what I thought, so I just ordered replacement PTFE tubes. Since it is my first 3d printer I was unsure if changing the PTFE will solve the actual issue at hand.

So, Atomic pulls and definetly change the tube.

Cheers,
Markus

Re: Defective PTFE Tube - unable to load filament

Hi Marcus

remember that the black ring on top of the extruder heatsink, is intended to stop the PTFE pulling out

if you are actually trying to pull the ptfe out, you need to press the black ring in towards the heatsink, to release the grips inside.

as you will have the extruder housing dismantled to complete this task, it is often easier to unscrew the heatsink from the stainless steel heatbreak, and push the ptfe into the space left, inside the heatsink, rather than pull it out...

however, I have had one PTFE tube, stick inside the heatsink... as I had a spare heatsink, I replaced the heatsink in that instance

regards Joan

Re: Defective PTFE Tube - unable to load filament

remember that the black ring on top of the extruder heatsink, is intended to stop the PTFE pulling out
if you are actually trying to pull the ptfe out, you need to press the black ring in towards the heatsink, to release the grips inside.

as you will have the extruder housing dismantled to complete this task, it is often easier to unscrew the heatsink from the stainless steel heatbreak, and push the ptfe into the space left, inside the heatsink, rather than pull it out...

however, I have had one PTFE tube, stick inside the heatsink... as I had a spare heatsink, I replaced the heatsink in that instance

Thanks for the tip, I just recently read the guide on replacing the PTFE tubing here: http://manual.prusa3d.com/Guide/How+to+replace+PTFE+tube/82 but will keep in mind what you suggested.

Since prusa shipping will take a couple of days, will any PTFE tube with inner diameter of 2mm and outer diameter of 4mm work? I could get some from a local store way faster than from prusa directly.

Cheers,
Markus

[edit] changed outer diameter from 3mm to 4mm

Re: Defective PTFE Tube - unable to load filament

Ah, never mind the question about the PTFE Tubing, it looks I found it already:

http://manual.prusa3d.com/Guide/How+to+trim+PTFE+tube+-+MK2-S+%28Single+extruder%29/500

4mm outer, 1mm inner diameter :-).

Cheers,
Markus

Re: Defective PTFE Tube - unable to load filament

Gi Markus. Its 4x2 for single extruders. Yes any supplier should do.

The mmu is different

Regards Joan

Re: Defective PTFE Tube - unable to load filament

Hi Joan,

so I did some atomic cleans with no real success regarding the loading issue. The piece of PLA popped out clean and nice but shows no traces of grind or sorts.
I noticed that when I cut the filament and insert it with the chamfer facing towards the split of the PTFE tubing the filament load works pretty reliably. I am wating for the replacement and will report back, but I am pretty sure it's the tubing.

Cheers,
Markus

Re: Defective PTFE Tube - unable to load filament

Okay then, I replaced the PTFE tubing and took a picture of the old one (see attachment). It was definitely split but the new tubing does not solve the issue at hand.
I am starting to think that there is some sort of displacement in the filament path between the hole of the PTFE tubing and the gear which pushes the filament downwards. Maybe unprecise extruder part where the tubing goes in?

I can reproduce the hobbing problem everytime I insert the filament with the chamfer facing towards halfway the gear and the stepper motor. If I load the filament with the chamfer facing in the opposite direction loading works fine - every time. I guess I could live with that, but shouldn't I be able to insert the filament regardless the chamfer's direction?

Any suggestions?

Cheers,
Markus

Re: Defective PTFE Tube - unable to load filament

Try aligning your hobbed pully better. It looks like it should be a hare closer to the motor side based on the pictures.

Re: Defective PTFE Tube - unable to load filament

Try aligning your hobbed pully better. It looks like it should be a hare closer to the motor side based on the pictures. It also looks to be a hair short. It should (almost ) but up to the gear.

Re: Defective PTFE Tube - unable to load filament

Thank you devdoc, indeed the gear was slightly misaligned, I changed that and now the filament loads reliable again.

Unfortunately the ptfe tubing can't be pushed further towards the gear since it comes pre cut from Prusia. For what it is worth I also think it should be a bit longer to eliminate any unguided path the filament could possibly take.

Cheers,
Markus

Re: Defective PTFE Tube - unable to load filament

Thank you devdoc, indeed the gear was slightly misaligned, I changed that and now the filament loads reliable again.

Unfortunately the ptfe tubing can't be pushed further towards the gear since it comes pre cut from Prusia. For what it is worth I also think it should be a bit longer to eliminate any unguided path the filament could possibly take.

Cheers,
Markus

Glad it helped. You can always pick up some bulk PTFW on Amazon reasonably. Just look for ones with excellent reviews and Prime in the event you are not satisfied, but if everything is working for you now, leave it, and just stock up for the future. It is a wear part of sorts.