These pages are the complete instructions for building, commissioning and using the RepRapPro Ltd Tricolour Mendel and Mono Mendel. They are mirrored on the RepRap Wiki here.

Like all RepRap machines, RepRapPro Mendels are fully open-source. They are licenced under the GPL. All the design files and software are available from the RepRapPro Ltd Github repository. If you want to print the plastic parts for a RepRapPro Mendel, see the appropriate section of that repository. RepRapPro Tricolour Mendel is based on the previous RepRapPro Mono Mendel with many alterations and additions. It was designed in order to further simplify assembly and to increase build volume when using multiple extruders.

These instructions document the assembly of a single material/colour “Mono” Mendel. The extra Tricolour instructions follow the Mono instructions.

It is recommended that Tricolour machines are initially assembled as Mono Mendels, before being extended to Tricolour machines after commissioning, and you have gained some experience using the Mono. You are building a complex machine – the skills required and the rate at which you learn mean that troubleshooting when you have built it all at once is much more challenging.

For the most part, the construction of the Tricolour is the same as for the Mono. At various points there are small tasks that you need to do for the Tricolour. These sections are highlighted in green on the relevant pages.

General notes

Give yourself plenty of space and ensure your work area is clean. Dust and dirt are a 3D printer’s worst enemy. All printed parts have been printed on various RepRap machines from suppliers within the RepRap community. Despite the fact that these machines are highly tuned RepRap 3D printers, some holes and features may need a little fettling to get the best performance from your machine. This is especially true for the Igus bushings used for the Z axis. There is a video how-to on fettling 3D printed parts here on Vimeo.

Before you start the build, please ensure you have all the components as listed on the packing list included in the kit. If anything is missing, please contact us via email: Reprappro-em.png

BEFORE YOU ATTEMPT TO ASSEMBLE ANY PART OF THE RepRapPro Mendel 3D PRINTER, PLEASE READ THESE BUILD INSTRUCTIONS FULLY AND ENSURE YOU UNDERSTAND THEM. Although all parts are covered by warranty, this will be invalidated by your not following these build instructions. If anything is unclear please get in contact with support prior to assembly in order to ensure no damage caused to your machine.

The RepRapPro Mendel is a robust RepRap machine once assembled; however it does require a certain amount of care during assembly. If in doubt, force is usually not the answer! There are many ways to get support and advice, see the Get Support section below.

If you can’t see clearly from the pictures, they can be enlarged by clicking on them.

Hardware-only kits

You will need to print out the plastic parts yourself, if you have bought one of our hardware-only kits. The files are here:
Click on the ‘Download ZIP’ button on the right hand side of this page, to get all the printer design files. The individual stls are in the folder ‘Print-mendel/Individual-STLs’.
The extruder drive is used on both our Mendel and Huxley printers, so it has it’s own repository on github, here:

Table of Contents

  1. Frame assembly
  2. Y axis assembly
  3. X axis assembly
  4. Z axis assembly
  5. Heated bed assembly
  6. Extruder drive assembly
  7. Hot end assembly
  8. Power supply
  9. Wiring
  10. Commissioning & Software Installation
  11. Printing
  12. Multi-colour/multi-materials
  13. Maintenance
  14. Troubleshooting
  15. Improvements

Get support

If you find you need help or advice with assembling, commissioning or using your RepRapPro Mendel 3d printer, you can use the following channels:

  • Check the troubleshooting pages for common issues like connection, extrusion, sticking and printing problems.
  • Our Forum. This sub-forum deals with the RepRapPro Mendel. Other sub-forums on the site deal with other eMaker and RepRapPro models.
  • Reprappro-em.png

Tool List



Tools required for the mechanical build of the RepRapPro Mendel 3D printer:

  • Drill bits including 2mm, 3mm, 6mm and 8mm
  • Precision screwdriver set
  • A set of metric allen keys including:
    • 2mm (M2.5 size)
    • 2.5mm (M3 size)
    • 4mm (M5 size)
  • 13mm spanner (M8 nut)
  • 8mm spanner (M5 nut)
  • 5.5mm spanner (M3 nut)
  • 5mm spanner (M2.5 nut)
  • 15cm adjustable spanner
  • Half round needle file
  • Craft knife
  • Fine tweezers
  • 300mm rule
  • Vernier or digital calipers
  • Square
  • Fine nosed pliers
  • Pliers
  • Side cutters
  • A small amount of superglue (for securing the hobbed insert)


Tools required for the electrical build of the RepRapPro Mendel 3D printer:

  • Digital Multimeter
  • A fine-tipped soldering iron
  • Precision screwdrivers
  • Solder
  • Hair dryer or cigarette lighter (or other heat source for heating heatshrink wire sleeving; the barrel of a soldering iron works OK)
  • Wire strippers/cutters
  • Crimping tool (very useful, but not absolutely necessary; you can do it by hand)
    • EITHER Ratchet crimp tool Such as this one, which we use
    • OR Molex crimp tool (such as the 63811-1000, you may also want the extraction tool 11-03-0044,
  • Scissors