Filament without attachment to spool  

RE: Filament without attachment to spool

That would be pretty difficult to do. How would you wind the filament on if there was no anchor on the spool you are going to turn?

RE: Filament without attachment to spool

Oh, there are options, I just need to find somebody who applies them (and has the colours and materials I want, of course). Regular office tape works great, for example. You can also stick the filament through one of the holes on the rim instead of through the spool core to keep it accessible for a clean cut.

RE:

Hmm that's a pretty good question, so I took a photo of my spools that I print, I don't remember having issues with them ... yet.

Prusament PETG Jet Black 

Devil Design PETG White

Fiberlogy PETG Yellow

RE: Filament without attachment to spool

The DevilDesign and Fiberlogy spools both appear to have hard kinks right at the end where the filament is hooked to the spool. I can't tell if the Prusament has the same issue. Even if these filaments fall off the spool cleanly at runout, I've had issues with kinks like that on my old MK3 where the kink can't fit through the entrance hole to where the filament runout sensor is. I also remember having issues on my MK3 with some filament (especially at the hub) having enough curve that when the filament runout is triggered the ejection misses the hole and the remaining stub is stuck inside the extruder. I made it a habit of trying to cut the filament off the spool once I could reach the end (either when the penultimate filament wrap on the spool exposed the end, or during the last filament wrap on the spool where I could loosen the last bit of filament) to get rid of hard kinks in the filament or remove the tape holding the filament to the spool (I see you PrintedSolid).

I haven't (yet) had a filament runout on my MK4S so I don't know if there will be an issue. But since my MK4S is in the Prusa enclosure, I would expect a kinked end of filament to get caught on the start of the reverse bowden that is part of my enclosure.

RE: Filament without attachment to spool

That's why I weight spools before the print and I know how much filament there is and what model I can print, so it fits in the spool.

I wonder if there could be some kind of filament detector modification to detect the end of filament but for the filament with a kink at the end...

RE: Filament without attachment to spool

Posted by: @_kaszpir_

That's why I weight spools before the print and I know how much filament there is and what model I can print, so it fits in the spool.

I wonder if there could be some kind of filament detector modification to detect the end of filament but for the filament with a kink at the end...

Weighing the spools isn't practical with my setup.

A mod? I can think of two: Either watch the spools with a camera and use AI to detect the last winding or use a separate stepper to feed the filament into a sensor equipped-buffer, from which the extruder pulls it and stop the print once feeding it fails. Neither is a "print this and problem solved" kind of idea, though.

RE: Filament without attachment to spool

try not to push AI everywhere 😀
if the filament is stuck to the spool then it would be possible to detect the fact that the spool is displaced

- if it drags the spool towards the wall through which the bowden tube goes to the outside
- could be detected when the tensor beam under the spool gets sudden spike because the spool is lifted

If the filament gets loose then it would be possible to detect a kink at the end of the spool also with a increased pressure because the hooked end would lock on the metal plate and trigger the sensor, otherwise the filament could be bent by the extruder and sucked into the pipe and there normal filament runout sensor would pick it up

RE: Filament without attachment to spool

Not pushing AI, it's just a great application for it and Prusa is working on it anyway.

By the time something gets stuck, it's too late. You have to preemptively pause the print at a convenient moment and, more importantly, in a known condition if you want to be sure to save it. If you wait for an issue to dictate your action, you can't be sure how exactly the extrusion looked in the moments prior. That's also one of the reasons why the built-in stuck filament detection doesn't work for me.

And I'm still annoyed that the solution would be so easy and yet nobody applies it 🙂

RE: Filament without attachment to spool

I struggle with this too.  Sometimes it comes off ok, and sometimes it gets stuck and strips out in the extruder.  The Prusament example wouldn't cause me an issue, it's the ones that are bent at 90° and go thru the center of the spool. 

I print almost exclusively Hatchbox and that's unfortunately how they do it 

When I see the spool getting low enough I push the kink out from the center and cut it off.  This is difficult because you need to catch it with only 1 or 2 layers of filament left on the spool or else you can't get to the kink. 

It's definitely a design flaw in the spools, I think what Prusa does all manufacturers should do.

RE: Filament without attachment to spool

Time consuming, but set up a rewinder and rewind the whole reel to another spool with the end set up the way you feel is best to release.

Teamwork, Steve 

RE: Filament without attachment to spool

Posted by: @reddadsteve

Time consuming, but set up a rewinder and rewind the whole reel to another spool with the end set up the way you feel is best to release.

Tried that. Works, but takes a few minutes per spool, introduces potential for me to mess it up and quite frankly I don't want to spend that time and re-do work that should have been done at the factory.

In my opinion, people should take enough pride in their work and product to consider what happens when it's used up. On most spools, the holes on the rim are literally right there as a solution and aren't being used for absolutely not reason, which leads me to believe that they just don't care.

More on topic: So far, I've tried:

• Extrudr - They use transparent spools that many other manufacturers also have (like Devil Design, see _KaszpiR_'s picture above) and they do have kinks.
• Prusament - If I remember correctly, there were no issues. I want different colours and finish, though. Only tried a single spool, might have been coincidence.
• FormFutura - Haven't reached the end yet. Cardboard spool with relatively large core hole. Filament goes through there, but no kink visible. Also only got a sample size of one spool here.

I'd be interested to know how the ends of the new made-for-Prusa and Buddy3D filaments look. If this is a checkbox on Prusa's quality control checklist, maybe they do it differently.

RE: Filament without attachment to spool

I only have 2 brands of filament.  Prusa looks like it is just slid through a side slot.  No kink or bend.  The other was pushed through a cardboard tube and was bent.  I could cut that with a flush mount side cutter.  Now there is only a small bend but shouldn't get caught on the spool.

A filament detector close to the spool with an alarm may be the best option if you don't want to watch the weight.  Should be easy to put one together and mount it so it feeds into the tube feeding the print head.  Depending on the length of the tube, you could get a long warning.

I have been looking at filament that doesn't ship with spools which may be the best option.

RE:

I mainly use the 2.2 kg ColorFabb economy PLA spools. The filament comes loose from the spool before the end. Thus, no problems on spool changes. (which don't happen very often anyway  with those big spools)

I know the circumference of the core of the spool is 64 cm. The slicer not only specifies the weight of the needed filament, but also the length. With a simple calculation I can translate that to the minimum number of windings on the spool. But this method only works for smallish prints.

RE:

Havent had any issue with Prusament, but on my BambuLab using Bambu Filament they actually tape the end to the spool!

Last weekend I was using the spool holder (not the AMS) for a single colour print and was coming to the end of a spool, so when it got to the last few coils and I could reach the end that's taped to the spool, I just snipped it. I then removed the empty spool, leaving the last few coils loose on the spool holder. 

This gave me ample time to take the spool apart and reload it with a refill, put it back on the spool holder, and as the last of the old filament was going down the PTFE tube to the extruder, I was gently pushing the start of the new roll directly behind it. lol 

Wasnt sure if it would work, but it did, and the print continued without error 😉