Robot Chassis Building Instructions
1.
Assemble motor according to instructions. Trim ~
1/8” from each end of metal axle with metal shears.
2.
Glue hobby motor to Lego 16-tooth gear with clutch.
Do not allow epoxy to get inside axle hole of hobby
motor gear (yellow), but if possible do fill in space
between hobby gear and lego gear.
Finished chassis (no legs attached)
Example battery pack
3.
Slide assembled gear onto axle and down to
motor housing.
Component Parts
4.
Insert a black Technic pin in the 3rd hole of a 15hole Lego beam. This is where the glued gears will align
to the lego structure. Note that a small washer may be
used to improve spacing between hobby motor and lego
parts.
6. Assemble the driving gear as shown, with a thin
Technic bushing, 2 hollow Technic spacers, the plain
16-tooth gear, and a wide Technic bushing on a 12stud long lego axle.
5. Insert a second black Technic pin in the 3rd hole of the
other 15-hole-long lego beam, this time facing towards
motor, and slide over other end of axle.
7. Insert the driving gear assembly as shown, and
secure with two wide Technic bushings. This
requires removing one long Lego beam to first slide
the driving gear assembly into place.
8. Assemble the motor support. This consists of two
technic pins with axle holes and 4-stud-long Lego
axle. This support is a bit loose, but only serves to
keep the motor from scraping the ground. It can be
assembled with the drive gear secured, though it
may be easier to do this step before step 7.
10. Add two Technic disks to the base axle. This helps
secure the frame and prevent interference with the
moving parts. Align the ends of the axle flush with the
disks; the long Lego beams will angle out slightly relative
to the gear assembly.
11. Assemble the leg fulcrum points using Technic halfpins/half-axles (blue) and Technic connectors shown.
9. Slide the 10-stud-long Lego axle through the last
holes of the long Lego beam to complete frame,
securing in place with two wide Technic bushings.
12. Attach the fulcrum points to the frame. Placement
of these connectors is very important. They should be
adjacent to the lower axle and midway between the
motor support and motor axle (holes in the fulcrum
connectors will be aligned with the 13th and 6th holes in
the long beams, respectively, as counted from the
driving gear assembly).
14. Insert Technic pins with ball joints in the 6th hole of
the long beam, even with the holes in the fulcrum
connectors adjacent to the motor.
15. Insert the fulcrum pins into the fulcrum connectors.
The pins have a Lego axle portion, to be inserted into the
connector from underneath the chassis, and a Lego axle
connection point. Once inserted, secure from above
with a narrow Technic bushing.
16. Begin linkage assembly by inserting a Technic friction
pin (black) and 3-length free-spinning Technic pin (tan)
into two of the 9-hole-long Lego beams, as shown.
17. Attach the second pair of 9-hole-long lego beams as
shown, then the 5-hole-long lego beams to the
remaining length of the freely-spinning Technic pins.
19. Begin assembly of leg guides with ¼ round lego hubs
as shown, by inserting 2-stud-long Technic axles in each
corner hole.
18. Add two ¾ Technic pins and a 2-length freelyspinning technic pin to each linkage as shown.
20. Attach leg guides as shown, using ¾ technic pins
from step 18 to secure in place.
21. Reinforce leg guide connections with narrow Technic
bushings attached on opposite side of linkages.
22. Assemble two linkage cams for connecting the
driving gear assembly to the linkages from Step 21. Each
cam will consist of two Technic discs held together with
2-3 Technic ½ pins, with a freely-spinning technic pin
attached from the opposite side. It is important that the
slots in each pair of Technic disks are aligned, so that an
axle can pass through eac.
24. Connect the linkage to the frame using the freely
spinning pin in each cam (to the end of the linkage) and
the freely-spinning pin in the 5-long beam portion of the
linkage (to the 8th, center, hole in the 15-long Lego
beam).
23. Add the assembled cams to the exposed axle on
each end of the driving gear assembly. Preferably, have
the freely-spinning pins oriented on opposite sides of the
axle, although advanced students may wish to
experiment with other pin locations.
(Opposite-side view)
25. Begin leg assembly by inserting Technic half-pin/half- 27. For better stability, a rubber band may be added
spinning-axles (tan) into right-angle Technic connectors, between the motor axle, pin with ball-joint, and leg
attached to 6-long Technic axles, as shown below.
beginning for each of the legs closest to the axle.
26. Connect the beginnings of the robot legs from Step
25 to the fulcrum pins, being sure to slide the legs
through the ¼ circle hubs.
28. Attach the Technic pin-to-pin connectors to each leg
beginning, as a place for students to add their own robot
leg designs. If assembled correctly, the leg beginnings
should swing back and forth in a roughly circular motion
from the fulcrum pins when the motor is powered.