Adjustable Extruder Drive Block Upgrade for Replicator 2X

Picture of Adjustable Extruder Drive Block Upgrade for Replicator 2X
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Digital thermometer.jpg

This tutorial shows how to assemble an experimental adjustable drive block for the Replicator 2X extruder. The purpose of this design is to allow the operator to fine-tune the pressure applied to the filament by the idler ball bearing.

Note: This is not intended to be a replacement for MakerBot's original extruder block! Since the Replicator 2X Desktop 3D printer is suited for power-users who like to experiment, this adjustable extruder block offers an alternative way of gripping the filament and pressure fine-tuning. Please do not attempt to replace your original block if you are not comfortable disassembling your current extruder and fix any issues. If you try this design, make sure to save the original parts and follow the instructions below carefully.


  • All parts can be 3D printed!
  • Offers step-less filament grip pressure adjustment
  • Built-in filament dust filter with sponge
  • Cover plate to protect stepper motor cables and connectors
  • Fasteners and ball bearing can be re-used from the original
  • Sturdy design

Parts list

  1. Base left (3D-printed part)
  2. Base right (3D-printed part)
  3. Lever left (3D-printed part)
  4. Lever right (3D-printed part)
  5. Bearing cover left (3D-printed part)
  6. Bearing cover right (3D-printed part)
  7. Stepper motor cable cover (3D-printed part)
  8. Knob bottom part (3D-printed part)
  9. Knob top part (3D-printed part)
  10. M3 Nylock nut (2 pcs)
  11. M3 countersunk screw - 23 mm (2 pcs)
  12. M3 countersunk screw - 6 mm (2 pcs)
  13. M3 hexagon screw - 35 mm (2 pcs)

Tools and materials

  • 2 mm hex key
  • Water pump pliers
  • Beak pliers
  • A few drops of super glue

Version history

This design is a variation of current Adjustable Drive Block Upgrade for Replicator 2 and 1, which in turn is a variation of Spring-loaded Replicator 2 Drive Block, which also derived from three other previous designs.


The MakerBot Replicator 2X Desktop 3D printer is best suited to 3D print models made of ABS plastic filament. In contrast to 3D printing with PLA plastic, ABS requires that the process occurs in temperature-regulated and stable conditions. Therefore the 2X has a heated build plate and enclosure to keep the inside of the machine warm.

Being an experimental 3D printer, the 2X requires that the operator understands its capabilities and functions. For instance what temperatures and print speeds are best suited for different shapes and sizes of models.

A simple rule of thumb is that the top hood is only needed when larger 3D prints are made. By adding or removing the hood in conjunction with leaving the front cover open or closed, you can regulate the temperature in which the 3D printed model is made. The temperature and flow of the air in the room where the 2X resides is also a factor to take into account.

It is notable that temperatures around the extruder mechanism can raise significantly when the enclosure is fully closed. During 3D printing the air around the printer reaches typically 50 °C to 60 °C.

It is important that the plastic parts of this adjustable extruder block are 3D printed in ABS plastic (not PLA) at 100% infill to give them the best strength and heat resistance. Please note that this is an experimental design and is not intended to be foolproof and work perfectly in every situation. If you try it, learn from your experience using it. :)

We designed the parts to be as sturdy and strong as possible to be able to cope with 3D printing temperatures for ABS.

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audreyobscura8 months ago

This is a great mod, thanks for sharing.

CreativeTools (author)  audreyobscura8 months ago

You're welcome!

AmpOwl8 months ago
I've been working on a 3D printer, and I need to decide on an extruder mechanism. All the others I've seen have gears to increase the output torque. Is this dependent on the motor's torque? (How strong does it have to be to skip the gears?) Is this design suitable for a bowden extruder?
CreativeTools (author)  AmpOwl8 months ago

The reason to have geared extruders in most cases is to be able to achieve slower 3D-print speeds and have a fine-tuned extrusion ratio.

The Replicator 2X has a 1:1 ratio since the drive wheel is attached directly to the stepper motor axel. The diameter of this wheel is enough to achieve high-resolution 3D prints at normal printing speeds.

onnyuk8 months ago
I have no clue about 3d printing, and have neither the desire or the funds to get into it just now, but I still found this instructable well written, informative and I enjoyed the pictures of the pretty coloured plasticthings
CreativeTools (author)  onnyuk8 months ago

Thank you for your kind words. :) Glad you found this interesting.

3D-printing for "home-use" is still a bit in its infancy but will evolve naturally by what the users prefer to make with it.

In our opinion it certainly already is very addictive ;)