Mendel assembly notes

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Mendel Build Documentation

Time and place

After preparing materials, the assembly should take a weekend. You will need at least 2 square meters of assembly space, some good tunes and copious amount of tea.

Assembly data sheet

The Mendel assembly data sheet enables the experienced ‘bot assemblers to survive with the spreadsheet alone. However, if this is your first time, the following pages will lead you through the assembly from start to finish, referring to the spreadsheet where appropriate.

Jig and Measurement distances

Using a spacer bar to calibrate the y-axis

Your machine will need careful calibration during assembly. Two different techniques are required: jigging and measuring. Jigged distances will be labelled on diagrams with a “J”, and measured distances will be labelled on diagrams with an “M”. You will need refer to the Mendel assembly data sheet for the value of these distances.


Use spacer bars to calibrate common distances. A good arrangement for the y-axis jig is to tape a longer bar over the top of the spacer bar (see pic) to achieve a perpendicular alignment. The top bar only has to be longer by ~10 mm at each end. This arrangement is not necessary for the other two frame jigs. Another good method is to use threaded rod with nuts at the right distance. If you twist the nuts in opposite directions you will lock them.


Best use a zero ended rule if you have one, but an everyday ruler or tape measure will suffice.

Important assembly notes

  • Always use plain nuts in captive nut traps in RP parts. Never use nylocks as the rotation force might strip the flats in the trap.
  • You can use regular nuts instead of nylocks, you just need to apply a small amount of a thread locking compound to the last few threads of where it will be in its final place, LocTite 243 works well. See notes tab of Mendel assembly data sheet. Super glue will also work as an alternative to LocTite, but you only need a tiny droplet to prevent nuts from loosening themselves from operation of the machine.
  • Apart from the above case, use nylocks wherever possible as this reduces the likelihood of fasteners loosening due to vibration.
  • Don’t skimp on washers for the same reason as above.
  • Fully tighten all nuts as you assemble unless instructed to do otherwise.
  • Always enclose a bearing with a standard washer each side to ensure smooth running (see pic).
  • You may find that some plastic RP parts have snug fits & tight thru holes. You may consider reaming all of the holes out for all of your plastics at the very beginning of your build (highly recommended if you find interference early on). In this regard, you can avoid threading all of your screws into the plastics themselves, and focus on getting those screws directly into their intended mating fasteners/nuts.

Caution: Always read datasheets for all adhesives, as they are poisonous!


Back to Mendel mechanical construction root.

assembly videos

There are some assembly videos posted in the RepRap-forum.