I’ve just been taking the filament off a roll so I could rewind it because it had the trapped loops. Even as I was getting down to the bottom of the roll, I was still seeing this trapped loops, even though the filament was tightly wrapped. What was obvious during the unwinding is that the filament was wrapped very unevenly, there were distinct mountains and valleys. My hypothesis about the cause is that loops N and N+1 were on a local high point (a mountain), loop N+2 got wound onto a low point (a valley), and then loops N and N+1 slid off the high point to cross over the low point containing Loop N+2.
This is a roll of PETG from MG Chemicals. The filament itself has been fine, but the winding indicates to me that trapped loops can start before you get the filament out of the box.
Technically it should be impossible as long as both ends are secured. 99% of the time it’s caused by the end user. typically the loose end is released, then it unravels and slips under a loop.
Correct me if I’m wrong, but I think I’ve just explained how it is technically very possible. An end does not need to be free for earlier loops to slide on top of a later loop that is in a valley.
Actually what you described would have a symmetrical even number of a crossing points. Having a section of a loop bury itself into the spool will not cause a knot. The “earlier” loops should just slip off.
Oh, its not a knot per se, but it does trap the filament until you loosen things. You can hear your extruder straining when it happens.
Well this thread took a turn for the spammers.
Edit: reporting spammers. Whew.
@Eaglo_Techo screw off with your spam! Reported!
Ugh. Report the app too. The way they’re advertising, I’m going to bet that it’s actually malware.
Personally I’ve never ran into this issue. It sounds like it’s a problem with the way the filament is wound up. If that company is winding their spools really tight and not making sure that the plastic is being wound evenly back and forth, it could easily cause this issue. Personally I would suggest a different brand as their method seems to be an issue. If it’s so tight that you can hear your motors struggle, that’s more heat and amperage, along with possible issues of under extruding due to the motor skipping or just not being able to push plastic out. Either way, I’d say try a different brand. Personally I’ve been using ZYLTech ( I think that’s what it’s called) and it’s been great. Here’s a link.
I don’t have to worry about that! Found some great filament that is wound…well, perfectly! From http://schoon.com
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I certainly won’t be buying from MG Chemicals again. The schoon winding looks fabulous, but they don’t seem to carry petg. I might try the ZLTech next, after I babysit my two unopened rolls :-).
I can attest this does occur and is a common problem with the lower market cheap filament manufacturers and is indeed cause by poor spooling on their end. I have numerous spools from the early days where when unwinding would get caught and either strain the extruder or outright jam the gears and be ground away into dust causing an air print. Most of the better companies like colorfab, polymaker, etc. don’t have this issue and their spools are very very nice. I too think i have an mg chemicals spool 'black" if i recall, and I had to use side clippers because of trapped over under strands, over and over ,and used the resulting meters of pieces to print out smaller items. http://www.dbclunie.com
