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RailcoreII is a CoreXY-based RepRap 3D printer designed by J. Steve White and Tony Akens and published under the CC Attribution Only license. The initial collaboration behind the RailCore started in the #reprap IRC channel and centered on some common goals for a new printer design.

These goals were:

  • CoreXY motion
  • All linear rails for movement
  • Space and cost-efficient with an enclosable frame
  • Key components being printable or able to be milled
  • Flexibility, customizability, and scalability built into the design
  • Professional-looking
  • Can be self-sourced


J. Steve White had previously built the Railcore - the alpha version of this printer. Lessons were learned and the design on the new printer began. All design work was done in Fusion360.

As it progressed, we decided to publish this printer in an open, documented format for others to build as well.


The frame is designed to use 1515 aluminum extrusions. This was a space-efficient choice, which makes building the printer easier, as standard M3 hardware fits nicely into the extrusion like T-Nuts would. To add rigidity, we use sides made from HDPE to stiffen the frame. (These can alternatively be cut out of any material you prefer, including melamine, plywood, acrylic and aluminum.) The total cost for the actual frame components (extrusion, corner cubes, and sides) is roughly $100 USD.

Notable aspects of the design include:

  • 3 trapezoidal lead screw Z-axis, stacked idlers, and duo-planar belt path
  • The electronics in the design are the Duet (Wifi or Ethernet), Duex2/5, 24v PSU and 0.9 degree steppers
  • We use an E3D v6 for the design, as it’s the most common hotend at this time
  • Support for other hotends such as Volcano, Mosquito, and many others are also available
  • Semi-direct drive or full bowden are both supported

Kits were originally built and sold by Project R3d. At the current time, Project R3d now assembles the bulk of the kit hardware, and works with distributors who customize and finish out the kits from there. This guide specifically covers the primary options of the most common kit configurations, but may work with only variations with kits from other distributors, or a self-sourced build.

If you need assistance with your build, a strong community of support is available at our discord channel:

A special thanks to Filastruder, Duet3d, E3D, SeeMeCNC, 713Maker ,Mandala Roseworks, and Project R3D for supporting the project.

Finish Line

29 other people completed this guide.

Tony Akens

Member since: 10/26/2019

10,600 Reputation

20 Guides authored


It would be great to add a section on Required and Recommended tools. In particular, these tools have proven useful:

Ball-end Hex Drivers, like Bondhaus, in 2mm size at least

A precision, tight, non-ball-end 2mm hex driver to avoid stripping button-head screws on tightening

Metal 1-2-3 alignment blocks

4x6” machinist square

Loctite (blue or green)

Max Plastix - Reply

Might add the Facebook group in here too…although the Discord is a much better way to get help.


Tony Pavlakis - Reply

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