Extruder Choice

Choose your Destiny!

As of fall 2011, your choice should be fairly clear — if you've ordered recently (after September 15th, 2011) you most likely have a Stepstruder MK7. If you're building an older kit, or requested a MK6+ so you could use 3 mm filament, you'll also find links to the documentation here.

Stepstruder MK7

The MakerBot Stepstruder MK7 is our first dedicated 1.75 mm filament extruder. This extruder was designed from scratch, and contains a number of custom manufactured parts. We’ve learned a lot over our past extruder designs, and incorporated a lot of those lessons here: that’s why it’s smaller, lighter, and faster to build. And since it’s designed from the ground up for 1.75 mm filament, it’s light-years ahead of past designs in small-filament reliability.

Next Step: Continue to MK7 assembly!

Stepstruder MK6+ 3mm Filament Setup


The 3mm filament setup is similar to the original MK6 (and the MK5 before it) in that it uses the tried-and-true "Paxtruder" thumbscrew method to compress the filament against the drive gear. However, in addition to the direct-drive stepper motor system from the MK6 (and its better reliability, configurable speeds, and high torque) you get the "Plus!" That's the new, cartridge-based heating method that makes for much simpler assembly, heats faster, and eliminates yet more points of failure.

Next Step: Continue to MK6+ with 3mm filament!

Older Extruder Options

Stepstruder MK6+ 1.75mm Filament Setup


As you may know, 1.75mm is the way of the future. It might even be from the future. We're not sure, but it's good stuff — less torque, less ooze, and easier extrusion through smaller diameter nozzles. This option uses the same Delrin spring as in the Mk6, but adds the new "Plus" feature of the cartridge-based hot end, for faster heating and even better reliability.

Please note: "Way of the future" also means EXPERIMENTAL! 1.75mm filament does require more TLC than the 3mm configuration; this is ideal for tinkerers, intrepid hackers, and other folks who love to live on the bleeding edge.

Next Step: Continue to MK6+ with 1.75mm filament!

Do see see some resistors like this in your kit? (Make sure they are 5 Ohm rather than 5K Ohm power resistors.) Was your kit shipped prior to April 2011?


In that case you probably need one of the following sets of instructions, which have been archived for your convenience.

Stepstruder MK6 3mm Filament Setup

The 3mm filament setup is very similar to the Plastruder MK5 in that it uses the "Paxtruder" thumbscrew method to compress the filament against the drive gear. The major MK6 improvement to this design is the replacement of the troublesome DC motors with an extremely reliable and more precise stepper motor. A stepper motor extruder allows control over flowrate as well as the ability to retract filament during a build to virtually eliminate unwanted ooze and strings. The MK6 stepper motor measures in at a whopping 100 oz-in of torque enabling the use of a direct drive setup. Direct drive extrusion means there is no gearbox on the motor so there is no need to account for backlash (extra play in the system when reversing directions), and it also enables very fast filament retraction speeds at an instant.

Next Step: Continue to the 3 mm filament configuration assembly

Stepstruder MK6 1.75mm Filament Setup

The 1.75mm filament setup is a step forward in the endless process of simplifying plastruders. From a scientific standpoint, smaller filament extrusion has benefits in nearly every category: It requires less torque to operate, has a much smaller bend radius, is easier to spool, and best of all it produces a smaller amount of unwanted ooze. Another significant advantage is that it's far easier to extrude through smaller diameter nozzles which translates to better resolution in prints. At this time, Makerbot does not yet offer the tools for achieving better resolution using the smaller filament, but it is the clear path into the future of maximizing print quality. The most significant difference between the two Stepstruder MK6 setups in terms of hardware is the new Delrin plates. The 1.75mm setup uses a laser cut Delrin plate with a built-in "bumper" to apply a consistent force against the drive gear and eliminating the need for the thumbscrew and plunger.

Next Step: Continue to the 1.75 mm filament configuration assembly

Plastruder MK5

If your motor is a silver cylinder instead of a black rectangular prism, this is probably the option you need.

We've logged many, many hours of printing with the MK5: it was the original launch extruder for the Thing-O-Matic. All kits shipped prior to mid-February 2011 include this option. It's a sturdy design with the steel-core hot end and a high-torque DC motor. It's compatible with 3mm filament only.

Next Step: Continue to the Plastruder MK5 assembly instructions.

Next Step: Body Assembly

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