Hi everyone,

i just wanted to inform you about my problems with brittle filament.

I have printed with leapfrogs MAXX Economic PLA (white) which is as brittle as normal PLA.

After printing some parts the filament broke at the steppermotor (without me noticing) aswell as breaking at the end of the teflon tube that leads to the spool holders.

This means that there was filament stuck in the tube, so far not that much of a problem.

But (!) for absolutly no reason the teflon tube that connects the spoolholder and the extrusion motor (where the filament is stuck in) has an inside diameter that is very much bigger then the filmament diameter (1,75mm).

This means that the filament that got stuck can’t be removed with other filament that you push through one end.

The stuck filament creats so much friction, so that it’s not possible for the extrusion motor to pull the filament that i fed though the additionally.

So make sure, that you pull all filament out of the tube when changing it. If you have this problem you have to disassemble both side pannels (white) aswell as the cover just below the belt that connects the Z rods.

Finally it would be very good if a leapfrog official sees this so that the printers that will be produced have a teflon tube with an inner diameter of 2mm or similar. A tube where more then one line of filament fits in just provoces problems like the one i had.


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This is a good idea Marius, pass this through to Leapfrog

Else this system is very nice because you never get filament that is tangeled such as with printer with an open filament feed

Whenever I got filament stuck in the tubes I just used 1.5mm copper wire to push it out.

Hi Marius,
I use the same filament with Creatr and at each change of filament I put a little WD40 spray at the entrance of the Teflon tube for lubrication and never had this problem. You can even find few models on thingiverse for this purpose, like a box for mounting in front of the Teflon tube entrance in which you put a sponge soaked in WD40.
Hope it would be helpful for future use but I understand it would not solve the problem once the filament stuck… Maybe you can try with air compressor or with pushing 3 mm filament if you have one?

Hi, Thanks for the tips to solve this issue, I guess the hole in the tube’s ending is too small for a 3mm string or filament but I did test that. My main point of criticism is, that there is absolutely no reason for the tubing to have such a large inner diameter. -Marius

Hi, it seems a little bit odd to me, that the wire can push out the filament as (at least my tube) has such a big inner diameter, so that the wire might go beside the stuck filament instead of pushing it out. I will try this the next time the filament gets stuck. -Marius

No problem, I understood your point and it may be true even I didn’t thought about it that way… I thought the tube it’s bigger because of easier bending, when the extruder head is in opposite corner/area of zero point filament has more space for bending in tube if it’s bigger and the friction is smaller if it doesn’t rub the tube the whole way through it… But it’s just my oppinion.
I also noticed if you keep your filament unsealed ,it may dry out or absorb the moisture from air (depending from air in your environment) and that can be the reason why the filament broke. Keep it sealed when not using and lubricated when using and everything should be fine.

  • The economic stuff from leapfrog indeed breaks after a while, my advice; remove the filement after printing if you are not planning on printing the same day, before you start, check the first piece of filament, you can break it… Clip of the beakable part (usually the first 30 cm) after that the filament usually does not break anymore

Hello Marius,

Maybe you can use a much thicker filament / object to push the stuck filament through the tube?

BTW: I don’t understand why there is so much friction when the tube is very much bigger then the filament.


It works, you just have to pull it out really fast when you want to take it out or risk having some of the filament that gets stuck to the wire solidify in the upper parts of the channel.

Hi Renée, The friction is caused by multiple strings of filaments that get stuck next to each other, when one gets pulled by the motor the filament rubs on the broken parts that got stuck in the tube’s. -Marius

Had the same problem recently . I’ve rise the heat on my print head from 190 to 200. This allowed the plastic to flow more fluidly in the print head so it was less stressed when passing thrue the geared thoot in the motor pusher.

I was able to finish the print

Hi Marius

When filament get older and colder it becomes more brittle. I had the same experience with cheap filament so now I am using a better quality. No breaking since then.


Marius did you make a ticket or a forum topic for it at Leapfrog?

I’ve been printing PLA for about 5 years now and what I have found is that some PLA filaments break in several places within the teflon tubing if left overnight on my printers. Most PLA filaments don’t do this. I have never had ‘natural’ (clear) PLA break inside the teflon tubes, but I have had colored PLA break. One of my printers has been loaded with the same spool of transparent PLA for over two years (I only print a very low volume of small parts with this PLA) and it never breaks and it always prints perfectly, even though the spool has been in open air for a couple years. This is on a 3-extruder machine (BFB 3D Touch), so when I use it to print in another color, I load it into one of the other extruders. Sometimes, if I leave the PLA in the printer overnight, it breaks in many places within the tube, but nowhere else, and it breaks right up to the end of the teflon tube, but not outside of it. Logic tells me that there is some kind of reaction going on between certain (but not all) PLA filaments and the teflon that causes the PLA to become very brittle.