http://www.thingiverse.com/thing:468872 with replications on different 3D printers + latest STL file updates!

This Spider Rover can be simply clicked together with one and the same lock washer type. No screws required. Just in case you want to do more extensive research with it, you can add a motor. Pulley is in the files. The silver spider rover is 50% scaled down (not motorized), which needs the different named worm_gear_scaling.stl.

Be adviced that you have to be good in what you are doing when you start scaling down below 80% or if you add a motor to get it walking!

Used UM2 Cura 14.07 settings:

Quality
Layer height (mm): 0.1
Shell thickness (mm): 0.3
Enable retraction: yes

Fill
Bottom/top thickness(mm): 1
Fill Density (%): 100

Speed and Temperatur
Print speed (mm/s): 50
Support type: None
Platform adhesion type: None (e.g. leg_shoulder.stl could require Brim)

Machine
Nozzle size(mm): 0.3 (yes 0.3 - you can check gcode with Repetier-Host)

Quality
Initial layer thickness (mm): 0.3 (shows yellow)
Initial layer line with (%): 100
Cut off object bottom (mm): 0.0
Dual extrusion overlap (mm): 0.15

Speed
Travel speed (mm/s): 150.0
Bottom layer speed (mm/s): 20
Infill speed (mm/s): 80.0
Outer shell speed (mm/s): 50.0
Inner shell speed (mm/s): 70.0

Cool
Minimal layer time (sec): 5
Enable cooling fan: yes

Occured problems:

UM2 feeder underextrusion through moved hobbed
pulley to the outer side on the motor shaft. Followed by slight ticking sound.
Moved hobbed pulley back about 2.5mm. Last step of filament change has to give you a hard powerful knocking sound when new filament
is coming out of the nozzle (before you then select PLA/ABS type)

Scaling:

For example crazy 50% - It's easier to scale all leg_pins_..stl to 0.48 for X/Y and Z=0.5 instead doing sanding. For 1:1 no sanding is required !
If you really have to do sanding - use a common nail file.