Bites on filament

I´m having this problem with some filaments I opened several months ago. I try to keep them dry, but anyway I don´t really know what is the usual lifetime of an opened roll. This particular case is with FormFutura PLA Premium (same in 3 different colors).

When the printing starts it goes fine, but in some minutes, the action of the extruder wheel pulling for new filament makes this bites on it, bigger and bigger. I´ve already tried with the same model 4 times, but every time this hole appears and the filament stops extruding. Very frustrating.

Is there any solution or setup advice I could try? I have a TAZ5. Please, tell me I don´t have to throw this filament rolls to garbage… :cry:

I get the same issue with the second half of a roll of 3D Fuels APLA and the entire roll of Makergeek Raptor. I am no expert but I have tried drying my filament out in a dehumidifier and it did not help one bit. Tried with all different settings, turning retraction off, etc. Nothing. All of my other filaments are fine but these 2 are giving me fits… and I love the color of them both too! hopefully someone can chime in with a solution.

I will try to warm it a little bit to see if this makes any better.
Now I remember that I also had some ESUN rolls with very low quality that went unusable in just a couple of months once opened. But in that case the filament broke just with a little pression, I couldn´t even enter it on the extruder!

This one is still strong, and I can bend it without breaking. Is just that the metalic toothed wheel makes this on the surface. Now I´m thinking that I screwed more and more the two screws that hold the filament… Maybe too much and now I´m getting the contrary of what I need!

Tomorrow I will make some tests without screwing too much, let´s see if the TAZ can pull it in.

You say this starts happening some minutes into the print? You cancel, start over and then the same thing happens again? What if you bump the temp up? Next time this happens can you pull the filament and show what the end of it looks like? The end that was in the nozzle? Something is causing the filament to jamb and the hobbled bolt to dig into it instead of melt & extrude. What temp are you using?

Hi, DougZ. I think there is no jam on the extruder, the end of the filament is good. The problem comes before that. The wheel causes damage to this particular filament when trying to pull filament to enter the extruder. It grabs it the first minutes, but soon the metal tooths provoke a hole instead of pulling.

In the second picture you can see the results. On the right, a piece I printed with this same filament months ago. On the left, the new model printed yesterday. God, I even think I´m loosing quality apart from the extrusion problem! :frowning: But that´s another story.

I´m trying the same print with a difference: the screws that hold the filament to pull are not so hard now. I´ll post the results.


I fixed it!! What I did was tigh A LOT the two screws that hold the filament against the extruder wheel. This way the pression is so high that the bite holes never appear, and the filament is pulled perfectly.

You can see it in this picture: I started the print with the old screws pression, and after the first layers (about 1cm) I tighted the screws more. The problem dissappeared and the print went smooth until the end.

What a relief… I don´t have to destroy that filament rolls! :mrgreen:

That’s great! I thought about that when you mentioned it in your previous post but I could see the little teeth marks in the filament which made it look like you were getting a good bite. Is it just a really soft filament? Regardless, there’s a jig you can download and print from Lulzbot that will help you properly set the tension on your idler screws. You want there to be at about 8mm spacing and this will help you set it properly.

Download it from here:
As well, there’s a new, beefier idler and latch coming with the new Mini and you can find it on the Lulzbot website. I’ve been using it for a while now with success (unfortunately the above jig doesn’t work with new idler & latch). I noticed my idler constantly being loose, only to have the idler eventually break on me. No big deal. It is one of the spare parts you should print anyway.

I know it´s been a while since I wrote this post, but the problem is still here and I cannot get rid of it…

I found that the problem comes when the print has too many retractions (which in some cases I cannot turn off because of the model itself).
For example, if I print this model alone, it comes out perfect:

Instead, if I try to print the same model multiple times in the same print (40 in this case), the retraction when going from one piece to the next forces the filament to come up and down too many times, so the filament ends up bitten like the first picture I posted here. The first layers are goods, but when the infill starts, also the problems start.

I tried everything: thight the screws more, thight the screws less, decreasing the print speed, decreasing the infill speed… The only thing working a little bit (not always) is disabling the retraction completelly, but I would prefer not to do this to fix the problem. It seems to happen more in black filaments (PLA, PETG, etc.), I´m not sure why, but I cannot simply change the color, this needs to be printed in black.

Any ideas…? Thanks in advance.

I’m not an expert as well, but I would still recommend replacing your hexagon fan with something a bit cooler, if you didn’t already.

It does sound a lot like filament bulging to me.

PLA is susceptible to heat creep so upgrading your squirrel cage fan is a good starting point. I have had this issue on many different types of plastic due to retraction, lowering your retraction speed and distance can sometimes solve it, coast and wipe settings in S3D are very helpful to make up for a lack of retraction if you need it. Make sure your hobbed bolt is clean and do a series of cold pulls, particularly if you’ve printed in a different material, as debris in the nozzle can sit in there for a long time even if your extrusion looks clean and true. Finally, if the diameter of your filament is too large, this will cause it to happen. Any filament I’ve tried that averages over 3mm x 3mm this has happened to, also some which have the odd particularly wide spot where it can reach 3.1mm etc.

If this is happening primarily with PLA, I would strongly suspect that it is heat creep. The stock extruder fan on the Taz 5 is definitely not sufficient for preventing this.

I designed a shroud for a different fan, and it solved my heat creep problem 100%. My design is for the dual head, but I THINK it should still fit on the single head. Here is a thread I created describing the modification, it includes the files necessary to make the shroud and its mounting clip. Please note that there are two different mounting clip designs, the text describes the difference:

Since PETG was mentioned as well, I have had luck with increasing the hotend temp when printing with lots of retractions. It lowers the needed force to push the plastic through, so the hobbed bolt is less likely to strip the filament. For PETG I’m using, esun and makergeeks mostly, 265-275 seems to work best for me. Depends a bit on color.

Thanks all for your advices. I´m trying to test them one by one.
First of all, I measured the filament width and is a perfect 2.85mm, so that´s not the problem, I guess:

I tried this time applying A LOT of pressure to the two screws that press the filament (don´t know the proper name…,). Again, a new fail. I´ve been more than a week trying to print with the TAZ5 in this black PLA with no result (several rolls tried), this is so frustrating:

Each time the retraction starts also the problems. Even with ridiculous retraction values (speed 4mm/s and distance 2mm) the problem appears. Turning off retraction is not an option, this is a complex model that has a lot of empty space in the middle, I couldn´t reach it to clean it when it ends.

I´m SO worried about this… I guess I could try replacing the cooler fan, but I still think that this is not the problem as I can print well in other materials/brands, also in PLA.

I have found that a model that requires lots of retraction needs less idler tension and that black tends melt at a lower temp sometimes(depends on content of base materials). Also you might try smaller retraction distances as that tends to cause the filament to be shredded more by the back and forth passage on the bolt thus reducing pressure against the bolts surface.

The weird part is that I also have a cheap modified PRUSA i3 HEPHESTOS (using the same PLA brand and color) that can handle retractions of 25mm/s printing the same model without any problem, not matter how many retractions are involved (works on 1.75mm, but anyway).

The TAZ5 never gave me so much headaches as in the last weeks. It was “the tank”, unable to fail. Now I´m here testing with little retractions of 5mm/s, decreasing how many retractions are done in the same spot, decreasing print speeds to avoid the problem to appear again, etc. The piece was 15 hours to print, now I´m going to 25 hours… and I have to print 10 of them, what a nightmare. :cry:

I think I´m going to reprint ALL the parts involved in the extrusor. Maybe the wheels and gears are somehow eroded or grinded.

Finally, a successful printing! This time I increased the speed to 150% (applied to 60mm/sec) and tight the screws that pull the filament a lot. Retraction is on, I´m trying the same piece to see if I finally learned the “trick” with this PLA.