This is a complete walker robot with custom designed legs. The legs are specially modeled to print pre-assembled. The body and crankshafts are also printed pre-assembled. It only walks in straight line, making it perfect to carry salt and pepper across the dining table. Oh, and it will keep its body level while walking.
See it walking on http://youtu.be/fFPCq7Thvkk
The robot is composed of the following parts:
- printleg.lua - print 12 of these
- printbody.lua - print once
- printgears.lua - print once
- servo-mount.stl - print once
All models are modeled and printed with IceSL ( http://www.loria.fr/~slefebvr/icesl/ ). Simply drag and drop the files on IceSL.exe, setup parameters and slice. I used 0.2 mm layer height, 1 shell, 100% infill, 80 mm/sec speed (120 mm/sec travel) on a Replicator 1 Dual with ABS. The body can also be printed in 0.3 mm (it is a 3.5 hours print at 0.2 mm).
STLs are provided but I never actually used them for printing (IceSL generates G-code directly from the Lua scripts). Please comment in case of problem with them.
You will also need:
- a few screws (see pictures)
- 4 mm diameter metal tube, used as an axel for the legs (see pictures)
- a servo motor (I use a HS-311 modified for continuous rotation; very simple to do).
Note that the robot is fully functional but currently has to be powered by an external servo-controller (I use a Raspberry Pi). Once finished it will feature a small battery holder and servo-controler.
When printing the legs, make sure the first (bottom) layer is not too squished: The small inner circles should not bond to the body of the legs. I print the legs one after another. After printing, remove the leg from the platform and apply gentle stress on each joint. They should come free relatively easily; if not double check your platform leveling. It is likely that you will break one or two in the process, but the design has been optimized to reduce trouble. Legs are mounted at the bottom on the metal axel (cut a piece 4 mm diameter tube). The metal axel is snapped to both sides of the body. The top of the legs (hook-shaped) snaps to the crankshaft.
After printing the body remove the H-shaped support at the extremities of the crankshafts. The gears with a square hole are mounted on these square ends (make sure to push them all the way). Note that the body is printed upside-down.
The third motorgear goes onto the servo. The servo is mounted on the bracket, and the bracket is assembled to the body with screws (check the pictures -- use better screws than those shown here :) )
The legs have been carefully designed to keep the robot level during the walk, while being simple to print.
When doing the final assembly make sure the crankshafts are aligned so that the legs with most spacing on the left touch the ground together with the legs with smallest spacing on the right. The robot is slightly off-balance due to the servo -- I added a small mass to compensate on the other side.