Mendel On Darwin

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Mendel On Darwin

Release status: unknown

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Mendel X Axis on Darwin
CAD Models
External Link


The Darwin design has a flaw due to the orientation of the extruder. When the head is moving in the -y direction and it gets caught on something (like a bump in the part due to a flaw) it will rotate around the x-axis-rods, bending them slightly. This rotation moves the head in the +y direction and also down further into the part, which causes it to get stuck worse. Eventually, it digs nasty trenches in the part.

The Mendel design fixes this by putting the extruder in between the two rods. Now, whenever it gets caught, it will rotate up and get unstuck. This development is to design parts that will allow a Mendel-style carriage and extruder to be mounted on a Darwin Cartesian robot. This mostly involves modifying the x axis.

This will use the same belt and motor that is used by the Darwin.


Mendel X-axis on Darwin Render.
Mendel X-axis on Darwin Render.


mendel_x-axis_on_darwin_002.tar.gz These are openscad files. Mendel-style x-axis on Darwin. .tar.gz --Timschmidt & Nick McCoy04:44, 27 October 2010 (UTC)

Tim sayeth: Nick, a fellow MiRUG member, has had a Darwin running since forever, and he's had lots of trouble with his X axis / extruder carriage. We've put a fair amount of work into adapting the nicest (IMHO) Mendel X axis to Darwin.

Suggested Improvements

  • One of the walls on the x-end-idler is not straight, it appears to have a notch cut into it. There is no reason for this.
  • It is difficult to drill out one of the X-axis-rod holes because the motor mount interferes with the chuck from the drill. I had to drill it out with a hand drill from the other side because my drill press clamp is not tall enough the drill the hole from the other side.
  • Remove extra material between the belt clamps to improve print time.
  • There is a lot of sliding friction on the x-end-motor piece. This could be reduced by making it make contact with the y-axis-rod in only two places instead of the entire length of the part.