Filament Spool Tangled  

RE: Filament Spool Tangled

Because of the way filament is manufactured and spooled, it’s very unlikely to find a tangle in a given spool, although not unheard of. This usually happens when you loose track of the end and it gets under another strand in the spool. It can take a long time for that to catch up and jamb the spool.

The only way to guarantee this doesn’t happen again is to manually roll the filament onto another spool and look for tangles along the way. Going forward, try to always keep one hand on the loose end of your filament rolls when you change them out, then clamp or tuck them into a hole in the spool so can’t get loose. Good luck.

Cheers

RE: Filament Spool Tangled

I started a new spool of Overture PETG the other night where it seems like the filament went onto the spool twisted during the manufacturing process.  I have a spoolholder mounted to the side of my Bear feeding it through a reverse bowden, and this particular spool keeps having the filament come off and get tangled around the spool holder.  It's one of the ball bearing type holders, and when I mounted it I found right away there was actually too little friction, and the spool tended to overrun the filament.  I machined a couple plain bushings out of delrin to replace the bearings, which helped a lot.  But it could still use to have a little less friction with some spools, such as the current one.  Hopefully it will get better as I use up some of the filament.

RE: Filament Spool Tangled

@netpackrat - I recall your post about the filament holder rolling a little too easily.

My first thought was to design a ‘drag’ for the edge of the spool so you can adjust how easily it can roll. My first mini-bike when I was a kid had a brake that just flopped a slab of steel plate on an axle onto the flat surface of the rear tire to (attempt to) scrub speed. Sort of where the idea originated. 😂

Not sure which design you’re using for the spool holder so this may or may not be viable. Clearly you have the tools and the skills to machine parts as well as print them, so just another way to think about it. 

Cheers

RE:

Yeah it wouldn't need to be complicated.  I just read my post again and see that I messed up; what it should have said is that it could still sometimes use to have MORE friction, but obviously you knew what I meant.  Stupid edit time limit.  The spoolholder design in the batch of Voron parts I am printing uses a couple lengths of PTFE tube from the looks of it.  At some point it might be worth going into the stepfile and lengthening it so I can use it on the Bear and still clear the power supply case I used, which has the plug and the switch on the side.

Here is the spool holder I am using:

https://www.printables.com/model/34288-prusa-bear-2020-spool-holder-quick-change

RE: Filament Spool Tangled

Ive twice saved a print where the filament was getting tangled. I heard the printer trying to pull and was quickly able to come and intervene!

My issue was the end had wound under another loosened strand further on the spool. Luckily I was able to unwind a metre or so of filament and locate the crossover, which I then undone. 

Issue seems to be when printing, the spool turns and loosens a few strands all in one go - the spool doesn't turn as filament is pulled from it - its more in bits as the plastic is pulled, which looses a few strands at a time. Hence I'm now careful when unloading filament to ensure I keep hold of the unloaded end and temporarily 'hook' it under the frame of the printer, in the direction of it's natural curve. I only have prusa filaments and some of them come with a section where you can insert the filament end into a slot on the inner side often spool, which is a good solution. Others have holes to feed the filament end through, which I do not like using - it creates a kink in the filament, or sometimes the filament can snap off if you haven't pulled enough through and you're back to square one - so for these spools I just use a bit of masking tape to tape the end to the spool. I cut the end into an angle before feeding into the extruder anyways, so there is no risk of any tape adhesive entering the printer.....

I should really print off some filament spool hooks - plenty of examples online.....

RE: Filament Spool Tangled

FWIW, I’m using two of this spool holder on a stock MK3S+ frame:

https://www.printables.com/model/72737-frame-mounted-spool-holder-mk3/comments

I asked the designer if he would make a version that used a M3 screw and nut to hold the wheel half-frames together (because am sometimes clumsy loading spools) and he did.

I use this filament guide:

https://www.printables.com/model/5165-prusa-mk3-filament-guide/comments

Simple, works well, and I like that the honeycomb pattern ties into the spool holder arms.

I only mention this because I don’t think I’ve had any issues where the filament looped off a spool and caused a problem. I didn’t like the stock Prusa spool holder as it allowed the spools to rock back and forth and to sometimes ’thunk’ as they turned instead of rolling smoothly. This setup is working well for me so far. 

Cheers

RE: Filament Spool Tangled

I have had the exact same issue with two spools and couldn't understand why it happened until I read this post. That, once being ready with a spool, the end has to be firmly attached (stretched) onto the spool's outer wheel, or it may start free spinning and then we can have entanglement like this. Lesson learned.