Filament Spool Tension

[printerfan 5]

I've noticed that the end of a spool has significantly more tension than the start of a spool. Furthermore, occasionally tangles/kinks form in the filament.

1. How to mitigate tension when nearing the end of a spool of filament?

2. How to prevent tangling/kinking in a spool of filament?

3. Is the UMO spool holder adequate or is an after-market or 3d printed spool holder better? If so, what recommendations do you have?

[SandervG 1,518]

Hi Printerfan,

you could remove the last few meters from the reel so it can uncoil a little bit already. I believe some users also put it in the over for a very short time, to soften it and then straighten it. @Gr5, didn't you use to do this too?

When you open a new reel of filament, you should prevent it from untangling uncontrollably, cause that is when you can get tangles later on. You can use this clip to keep things in its place in between printing.

I think it is adequate, especially for the UMO. You could consider making one with bearings or put your reel on a lazy susan, but it should not be necessary.

[gr5 2,003]

When they make the spools at the factory they are made from one long piece of filament obviously and they wrap it perfectly with no tangles. But when they cut the end it can get under but they know this is a problem for users and most manufacturers hang onto the end and tuck it somewhere.

When the spool arrives you might want to be like me (like I used to) and never lose track of the end - never let go of it. Once it snaps loose it can get under another a loop so fast that it takes a slow motion camera to see it happen.

But lately I don't worry so much - I just unspool several meters and usually if there is a tangle you will notice in the first 2 meters and if there is a tangle I always fix it before inserting into the printer. Once it's in the printer it can't tangle or untangle without passing the whole spool through a kink... basically not likely to happen.

Printing the last tightest part of the spool - the last 4 meters - does have more friction so I tend to print that with thinner layers or slower. Save that stuff for prints that don't have to look as nice.

[geert_2 556]

For hard filaments like PLA, I usually unwind a bit of filament, then wind it in the opposite direction agains a skate board wheel (7cm diameter). Just half a turn of filament, about 15cm. Then I release it, take the next 15 cm, wind in the opposite direction around the skater wheel, release, next 15cm, etc... This straightens the filament a lot. In two minutes I can straighten about 3 meters like this. Then I let it wind up again on the spool. But now it is sitting very loose, and the unwinding resistance is near zero. Also, the friction in the bowden tube and nozzle is now near zero. Apart from straightening the filament, it also softens it a bit, so it adapts easier to any curves along its path. This avoids underextrusion too. It seems to increase life of the PTFE coupler too.

(But be careful with brittle filaments, such as particle filled stuff, as they might break.)

For more flexible filaments like PET it hasn't been necessary yet, but I am not yet at the end of my first PET spool.

[krys 206]

Hi there,

For my UM2 before I upgraded to the 2+, I had printed a filament straightener (adapted it a bit) and would use that for the tightly spooled parts. I had good results with this. Solved my under extrusion issues with the old UM2 feeder.

I wonder if it or something similar could be adapted to the UMO.

Hope it helps! Good luck!

Krys

[yellowshark 153]

Lol that is why I buy my most of my PLA from Faberdashery - they sell it in in loose coils, i.e. not wrapped around a plastic spool, so you get to use every cm without issue! I limit lengths to 50mtr, imho going above that probably makes it a bit difficult to handle.

Oh and I do not wind it around anything I just have the coil laying on the floor when n use.

[geert_2 556]

For my UM2 before I upgraded to the 2+, I had printed a filament straightener  (adapted it a bit) and would use that for the tightly spooled parts.  I had good results with this.  Solved my under extrusion issues with the old UM2 feeder.

 

Hello Krys,

I can imagine such a straightener works very well as long as the filament is moving, but doesn't it cause bends in the opposite direction, if the filament is left too long sitting still, for example overnight?

[krys 206]

Hello Krys,

I can imagine such a straightener works very well as long as the filament is moving, but doesn't it cause bends in the opposite direction, if the filament is left too long sitting still, for example overnight?

 

You know, I never had that issue. The straightener that I used, did not flex the filament very far in the other direction, so I never saw any kinks or issues, that I recall.

Now, I have had a spool of super brittle cheap/old/faulty crap filament and that stuff would break overnight just in the stock feeder! But I never used the straightener with that stuff. I did not dare!

So, I guess it is possible, but it never happened to me, even with cheap filament, even with the tiny 1 pound Taulman spools.

Maybe wood or Laybrick might have issues as they are more brittle apparently, but I never tried that.

Anyway, hope this helps.

[geert_2 556]

Thanks.