Filament in spool stuck midprint, snaping then causing damage!

Snapmaker 2.0
1

Hello,

I have found the machine this morning in a quite unusual state… I may say this might be one of those unlucky event. Hoping to find some solution here. Spool is Fillamentum PLA. Been very pleased so far with the brand.

As you’d expect, the filament in the spool has almost no tension when not connected to the machine, making the first couple of layers able to move around and sometimes mixed up/out of nice order. Most of the time, while printing, the line of filament leaving the spool for the extruder finds itself below a line of filament, creating a certain tension in the spool. I’ve never had any issue, most of the time the tension is released by itself as the filament moves around the spool.

Well, that was until yesterday! During my last print (I was not present) it appears that this tension never released, making the spool unable to rotate on the axle, making some sort of knot if I may say. But the extruder gears kept pulling until there was so much tension that the filament separated just short of the extruder. The spool then kicked back and managed to leave the axle and fell on the print bed.
I found the machine like this with substantial damage to the inside of the print head.

I have attached a couple of photos, with one showing the filament lying under itself as it leaves for the extruder.
I would like to hear your thoughts on this issue, and I would like to find a solution to this problem so that I do not cause more damage to the machine. How can I keep the filament nice and tidy, when in use and not in use?

Thanks for the help…
The filament runout microswitch got damaged, managed to glue it up in closed position making the machine serviceable again, but without this feature available anymore… don’t really care to be honest.

Stan

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2

Sorry for the problem you ran into.

You can use the command M412 S0 to disable the filament runout detection.

Examples

Enable (and reset) filament runout detection

M412 S1

Disable filament runout detection

M412 S0

Report filament runout state

M412
Filament runout ON

Edwin

3

Thanks a lot for your reply! I wish I had known that before gluing, even though it’s working fine now! :slight_smile:

4

Don’t know how you can fix the tangling, but adding a more substantial spool holder with an interior diameter smaller than the knob at the end of the axle would at least make it more difficult for the spool to fall onto the print bed. Thingiverse has several patterns.

5

The problem is the loose filament on the reel. You need to keep it under tension.
Unwind while keeping tension until you get to the original winding. Then rewind carefully making sure it isn’t crossing over itself.
As long as the printer is keeping a little tension while printing it should be fine. When the print ends and the head goes back to home, that’s when it can get slack again. Check before every print that it’s correctly wound.
I haven’t had a problem with having a smaller mount than the reel hubs. (I am using bearings on the original SM shaft) but you can find mounts on thingiverse that match the size of the reel hubs so that the tension is always constant.

If you keep the spool stored with the end fastened down it helps keep this from happening.

-S

2 Likes
6

That only happens when the end of the filament goes under an existing loop on the reel then it can lock just like a knot. Best way is to avoid ever leaving the end loose. when you remove the filament from the print head always immediately clip it into the holes in the outside edge of the reel. When you start a new reel, hold on to the filament after unclipping it and put it in the print head. Dont let it spring back on to the reel.

7

I was seeing marketing references to tangle and hadn’t had a single issue through the entire first Snapmaker reel and thought it was an old issue solved until I worked on extruder calibration. I had cut a measured section and didn’t pay attention to the reel…snake bite. I found the print incomplete and the filament snapped off. The filament had crossed and created a knot preventing the filament from feeding forward. Luckily after some melting, I was able to reinsert the filament. Rule #1…Take care of the filament be it humidity or wrapping. Don’t let it get loose during filament change or any other cases where the filament loses tension…This is old. I take my leave.

8

I have read an useful article in all3dp.com

FILAMENT SPOOL – TACKLING TANGLES

Solution

Untangling a filament spool.

Untangling a filament spool. Source: MatterHackers

No matter how stubbornly filament is tangled, one can always undo a knot without unwinding the whole spool. In fact, unwinding typically worsens the problem as the knot simply becomes more and more tightened through pulling the filament off the spool.

To get the knot out of the spool, you need to lift a few turns, including the knot, from the spool. If you lift too few turns and you can see three paths coming from the spool, then you haven’t caught the knot. More windings have to be removed until only a single path leaves the spool. Afterward, simply rewind the filament under tension again and undo the knot when you reach it.

An alternative method is to step-by-step unwind the filament while maintaining pressure on the point where the strand leaves the other spool. In other words, one hand will be both holding the spool and pressing — with one finger — the loose strand against the underlying coils. Everything “behind” this finger should be tight. Then, with the other hand, take hold of the loose strand, maintaining tension, and slide the pressing finger back along the strand. Continue doing this until the knot is directly behind your finger. Then, instead of sliding the finger back (this would only push the knot back), grab the strand from behind the knot, and pull the loose strand all the way through! Lastly, rewind the unwound filament under tension.

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FILAMENT SPOOL – TACKLING TANGLES

Prevention

A filament clip.

A filament clip. Source: Walter / Thingiverse

The most important thing is to always hold the end of the filament under tension until it is either in your 3D printer’s feeder or attached to the side of the spool. The latter is accomplished by pulling the end through a hole in the spool or fastening it with tape or a filament clip.

To prevent the filament from jumping off the spool by itself, there are many individually designed solutions depending on the spool holder. This can be a clip-on holder with arms that prevent the filament from getting over the top of the spool or something similar. Check out Thingiverse for upgrades for your printer.

A tangled coil can occur once in a while, but with the right background knowledge, the problem can be quickly solved and easily prevented!