Ultimaker 2 Bowden Tube Upgrade

Hi everyone,

Looking for a little expertise here. We have been having some issues with our Ultimaker 2 under extruding and grinding filament. After a bunch of playing around, it looks like the main cause of the issue is that the filament we are using is 3mm, while the machine was designed for 2.85mm. The problem is that 2.85mm filament is hard to find from the manufacturers we’ve gone through (Colorfabb and MadeSolid), so we are trying to use the 3mm filament anyway.

After adjusting the settings on the machine to work with 3mm filament, adjusting feeder tension and turning up the heat, it turns out that the cause of most of our problems is that the bowden tube the filament travels through is too tight for 3mm filament. After some research, it looks like the tube’s inner diameter is supposed to be exactly 3mm, which means a tight squeeze for 3mm filament with any irregularities.

To fix the issue, I’d love to upgrade to a slightly larger diameter bowden tube, but I need it to still fit in the current spots on the 3D printer, so the outer diameter can’t be wider.

I want to know where you get replacements for parts like this, and if any of you have upgraded your machine in a similar way due to a similar issue. Any help or links would be appreciated!


I would suggest to get a better extruder. Ultimaker sells the upgrade kit for the new plus model that contains a geared motor (offers more torque).

If you decide that the upgrade is to costly (as I did) you can get a bondtech extruder (bondtech.eu). The bondtech extruder features two gear like bolts (instead of one hobbed bolt and one bearing) and grips the filament from both sides. No more filament slipping or grinding here. They also offer better (more slippery) bowden tubes in two sizes.

I did this upgrade and I an very happy about its performance.