My Gooood! How to avoid failure printing due to cross tangle 3D filament?

[William.T]

I bought a 3D printer and learned a lot in the past 3 months. It is really a good thing that I can make some funny models and share with my friends. But some times I can not print the model successfully.
Yesterday I wanted to print an owl to my niece Joyce. It printed about 7 hours with smoothly surface, then the printer head was moving but lack of filament. The filament jammed on the spool due to cross tangle. What a nightmare it is! 7 hours nothing! I have confronted this issue in the past month but I thought it is a random issue. Don’t care that much. Now it is the second time I met. Does anybody can help to solve this issue?

Pity owl.jpg Cross tangle.jpg

[3DPBuser]

Some filament makers like Taulman use a wrap around it to keep it in place, but I'm not sure if you keep the wrap on it while printer.

Also, someone else posted somewhere that another filament makers was doing a "high quality" spool, where each layer on the spool was side by side.

[old man emu]

I find that the easiest way to prevent this type of problem is to:

1. Hang the spool from a hook in the ceiling (an indoor pot plant hook doesn't do too much damage to your house)
2. Determine how many metres of filament the print will require.
3. Unspool the required length of filament (and a little more) and let it dangle in the space between the ceiling and the printer.
4. Come back to the printer on a regular schedule to check that all is well.

By pulling the filament off the spool you will allow the filament to untwist before it gets to the extruder. That's another source of filament jam.

Those spool holders which are attached to the printer do make the whole set-up look neat and tidy, but they are often the source of problems with filament feed.

Old Man Emu

[oklok]

7 Hours Print then fail, I can feel your pain.

Usually when I do a long print the first thing I do is setup the spool on a external holder so I know it is friction free and free from being stranggled by itself. I then pull the filament so it is straighten from the extruder. Second is making sure the tube where i insert the filament is ok and that the tube has a good attachment into the extruder (so the filament do not scratch when entering the extruder).

When setting up the spool I manually extrudes 10 to 20 cm string to see that the wheel that pull the filament is ok and not sound strange.
Then of course I use a filament I know I have succeeded with before...then u are set to go

Btw I always put a pin in the roll holders hole, then the whole roll with the pin into a box, make sure it rolls good, then pull the filament into a tiny whole in the box to make sure it is straighten before entering the extruders tube----

[crisson]

I saw an ad for reprappertech.com that says they sell "newly coiled, no tangle" filament. I have never dealt with this company and am not vouching for the company or the product, but I did come across their site and thought I would pass along the info.

[awerby]

This seems like one of the stupidest design flaws in the FFF systems. Probably the ultimate solution will be to use a machine with a pellet hopper, which would be a lot cheaper to run. In the meantime, someone clever could probably come up with a modification of a fishing reel, which deals with the same issue pretty well, and 3D print it.

Andrew Werby
www.computersculpture.com

[EclecticAngler]

Andrew posted in another thread about my printed fly fishing reel and whether that idea might work to solve this problem. Now that I've read this thread, I understand the problem. There are two parts to the problem:

1) Is the original spooled filament "uncrossed". My experience based on 5 years of printing and literally hundreds of spools of filament used is that I've never received a spool that has a problem. That makes sense if you understand how they are spooled up to begin with (which is the same mechanism as spooling fishing line on a reel or spool). The filament is spooled onto the empty spool in a continuous operation. That guarantees that it can be removed exactly the opposite of how it is put on without a tangle. The one caveat being, for very thin diameter and/or compressible filaments (like dacron hollow braid) that is spooled with too much tension, the new layers can dig into the existing layers and get caught underneath them. This can lead to problems unspooling. This will not be an issue with our plastic filament due to it's diameter and stiffness.

2) crossing/tangling occurs when the end is not brought off the spool exactly like it was put on. It is very easy to do if you are not careful. If you've ever had the end uncoil a bit from the spool - perhaps spilling over the edge of the flange - you have to be very careful putting it back on to prevent a cross-over. If you get a cross-over, it can either bind up pretty quickly (if you are lucky) or inch its way along as the filament unspools and may not bind up for hours/meters of used filament.

You simply need to be very careful to secure the end properly when done printing so that you don't create a cross-over and if filament does unwind, be careful in how you respool it. I know from my experience that removing and starting a spool of filament in close quarters on my printer needs careful attention to prevent an inadvertent cross-over.

As filament feeds off a spool there is the potential for overrun too. This is common on fishing reels and usually creates a knotty mess. The stiff plastic we use is not so much of a problem and unless you have a perfectly centered filament spools on low friction spindle/bearings, the friction will prevent this over run.

Fishing reels usually have some form of guide too. This does several things but the most important thing it does for fishing line is during the retrieve - or respelling the line on the reel. The guide helps keep the incoming line centered to help lay down smooth layers. We don't have this issue to deal with because it is a one way trip for our filament! The guide also helps keep the line end from crossing over when the reel is removed from the rod for storage, etc. As long as the end of the line is left passing through the guide, there is no chance of it getting accidentally crossed on the spool. This could help with FFF printers as long as you are disciplined and always cut the filament "down stream" of the guide and then fix it to the guide for later reuse (with a piece of tape or a V slot to capture the filament). This would require a spool with an integral guide that allows the spool to rotate. A yolk-like arrangement would do it.

Hope this helps!

cheers,
Michael

[awerby]

I have limited experience with this sort of printer, but when I have tried to use one, as soon as I unwrapped the reel of filament the tension that kept it neatly coiled would be released, and the whole thing would go "sproing!", like a torsion spring that's suddenly released from captivity. The result was a loosely coiled mess that would inevitably jam as the filament was used. The fix we tried was to rewrap the filament on another reel, which is where the automatic guide would have come in handy. The rewrapped filament would unspool in a more controlled manner than the original, but it still had problems with tangling. If there was some kind of tensioning mechanism, perhaps a brake and filament retainer, that would keep the filament from loosening on the original reel and dispense it in an orderly manner, the rewrapping process probably wouldn't be required.

Andrew Werby
www.computersculpture.com