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.

Step 1: Download and 3D Print the STL Files

You can download the STL files for this project below for free. If you currently are unable to 3D print you can get in touch with us or ask a friend who has a 3D printer to print the parts for you. All the STL files are checked in netfabb and made fully 3D-printable. Please follow the instructions below.

  • 2X - Adjustable extruder (complete print plate).stl - Contains all 3D-printed parts for this project oriented to be printed in one go on a Replicator 2X build plate.
  • Base (1 pair).stl - The black base plate of the extruder block. It sits flat onto the shiny front surface of the stepper motor. This part has a built-in filament filter pocket where the filament guide tube is inserted.
  • Lever (1 pair).stl - The levers (right and left) of the extruder. This part holds the ball bearing which applies force to the filament and knurled drive wheel which grips the filament. This STL also contains the two small cover plates to keep the bearing in place and distribute forces.
  • Cable cover.stl - An enclosure or cover to protect the cables of the stepper motors from temptation to disconnect the cables when the power is still on (which is forbidden!) ;)
  • Knob_top_part.stl - The top part of the adjustment knob.
  • Knob_bottom_part.stl - The bottom part of the adjustment knob. It is glued to the top part to secure the screw head in place.

Material and infill

Use ABS plastic filament for this 3D-print and make it solid by choosing 100% infill. This consumes marginally more material but assures the highest possible strength of the parts.

You should not need to use raft or support structures for any of these files.

<p>Do you have the files in a format such as igs? I'd like to extract dimensions in order to attempt machining the components out of 6061 Aluminum. Somewhat more time consuming and involved than a print, but more durable. Plus I've got scrap stock about.</p>
Thank you for your comment. No problem :)<br><br>We have updated this instructable with the correspondent files in both .iges and .step formats.
<p>This is a great mod, thanks for sharing.</p>
<p>You're welcome!</p>
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?
<p>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. </p><p>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.</p>
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
<p>Thank you for your kind words. :) Glad you found this interesting.</p><p>3D-printing for &quot;home-use&quot; is still a bit in its infancy but will evolve naturally by what the users prefer to make with it.</p><p>In our opinion it certainly already is very addictive ;)</p>

About This Instructable




Bio: We supply tools and know-how for digital and manufactured creation. - http://creative-tools.com - http://google.com/+CreativetoolsSe
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