These UltiRobots starting smiling when walking down the road by them selves :)

It's very important to mount the legs proper into the body. The shaft (bolt), should be solid connected in the body. The legs should freely rotate around the bold and should not rotate/move in other directions. For more information about the way it walks, have a look of the patent (pdf below) from John E. Wilson, 1938.

Speeding up your walking robot:
* Adding some mass, will help the original running even faster.
* Play with different angels & roughness of your walking path.
* Remove the brim on the feet (or print w/o brim), so the surface is as round as possible.

See also the "Community Contest | a robot walks into a bar..":
https://ultimaker.com/en/community/20684-community-contest-a-robot-walks-into-a-bar

Here you find different models:
* Urobot 2e (stl & step): scale 1:1; both with & without support. (You could add support when slicing.)
* Urobot 2hh (stl): scale 1:1.25; uses a piece of unused filament as hinge point.
* Urobot 2e Moon (stl): scale 1:1; ultirobot for walking on the moon.

Challenge: create a single print dual material walking robot, leaving the build plate when printing is finished...