Replicator 2 Extruder Alternative: Some Spring In Your Step


The way that the MakerBot Extruder works out of the box is that there is a plunger that pushes the filament against the drive gear. We’ve shipped quite a few MakerBot Replicator 2’s into the world, and based on our data we can say that most people are having good luck with the existing design. However, there’s a bit of a sweet spot when dialing in the right plunger tension, and it can be tough to calibrate.

There are certain issues that the wrong amount of plunger tension can cause. For example, too much tension can cause a clicking sound when the end of the filament isn’t able to move past the drive gear. Too little tension can cause the filament to stop feeding altogether.

There should be a design that makes the process much easier.

Enter Thingiverse user whpthomas who came up with an improvement that has really seen some traction. It’s a great mod that makes the machine more reliable over the long haul.

Genius. We love this.

Thing #42250 “Replicator 2 Extruder Upgrade” by whpthomas, is one of these very useful designs. It’s based on an extruder mod from Thingiverse superstar emmett, who based his design on one from another star user, whosawhatsis. The basic idea of this series of designs is to use a spring-loaded arm to squeeze the filament between the drive gear and a bearing.

After extensive testing, we’ve decided that this approach is too good to ignore. We’ve modified this design to reuse the spring we already use for the build plate. We also added in a little bit of extra guidance for the filament where it enters the hot end of the extruder. Take a look on our Thingiverse page to see our adaptation of whpthomas’ great design.

We will be selling an upgrade kit that involves all the parts, including the printed part online this spring. We could have waited to tell you until we have enough to start selling them, but we decided that it would be good to tell folks about the mod.

If you have trouble with this upgrade, get in touch with our Support Team. They’re happy to walk you through some diagnostics, or you could download this design from Thingiverse and give it a try. The assembly instructions are there, too, and here’s a video to walk you through it step-by-step.

Remember, we are eager to hear your feedback, drop us a note at!


UPDATE! The hardware parts for this replacement are available for sale in our online store. Grab them here and build your new extruder!