Start with the build completed in Lesson 3 of the TETRIX Getting Started Guide. Step 1 involves removing an element from the model. This element will be reattached later. Parts to be Removed Step 1 1x NXT Ultrasonic Sensor Make sure to unplug the battery before making changes to the electrical system. Disconnect the cord attached to the Ultrasonic Sensor before removing the Ultrasonic Sensor from the model. 145
Bevel Gear Step 2 1x Single-Servo Motor Bracket 3x 5/16" SHCS 3x Kep Nut Make sure the screws are placed in the correct holes of the servo mount bracket and the front 288 mm channel. 146
Step 3 1x 180 Servo Motor 1x Single-Servo Motor Bracket 4x 3/8" BHCS 4x Kep Nut The first time using the servo motor, make sure to unscrew the servo screw using a Phillips head screwdriver to remove the white disk. The second bracket is screwed into the first to create a housing for the servo motor. Place all four screws in the correct holes of the servo and the servo mounts to align the holes and then screw on the kep nuts and tighten the screws. It can be tricky to get the kep nuts on the screws. Try holding the kep nut still behind the lower servo bracket while turning the screw into the kep nut with the appropriate hex key. Do not overtighten the screws; it might crack the plastic servo housing. 147
Bevel Gear Step 4 1x Servo Horn 1x Bevel Gear 4x 1/2" SHCS 4x Kep Nut Make sure the screws are snug. 148
Step 5 1x Bevel Gear Assembly 1x Servo Screw Use the servo screw that was removed from the servo motor in Step 3 Use the Phillips head on the 4-in-1 screwdriver to tighten the servo screw. Do not overtighten the servo screw. 149
TETRIX Add-On Extensions Bevel Gear Step 6 2x Flat Bracket 6x 5/16" SHCS 6x Kep Nut Make sure to attach the brackets to the correct holes in the 288 mm channel element. 150
Step 7 1x 160 mm Channel 1x Delrin Bearing 4x 3/8" BHCS Make sure to attach the bearing to the correct holes in the 160 mm channel element. 151
Bevel Gear Step 8 1x 160 mm Channel Assembly 4x 5/16" SHCS 4x Kep Nut Attach the 160 mm channel assembly so that the opening in the channel is facing forward on the robot. Make sure the screws are snug. 152
Step 9 1x 32 mm Channel 1x Axle Hub 1x Bevel Gear 4x 1/2" SHCS Make sure the set screw on the axle hub is facing forward so you can adjust it easily. 153
Bevel Gear Step 10 1x TETRIX Hard Point Connector 2x 5/16" SHCS 2x Kep Nut Do not overtighten the screws; it might crack the hard point connector element. 154
Step 11 1x 3 x 5-Module Angular Beam Make sure to insert the 3 x 5 beam in the right direction. 155
Bevel Gear Step 12 2x 3-Module Connector Peg with Friction Make sure to insert the connectors into the correct holes of the 3 x 5 beam. 156
Step 13 2x 3-Module Connector Peg with Friction 1x 3 x 5-Module Angular Beam Insert the two connectors into the first 3 x 5 beam and then attach the second 3 x 5 beam to the connectors. 157
Bevel Gear Step 14 2x 3-Module Connector Peg with Friction 1x 3 x 5-Module Angular Beam 1x NXT Ultrasonic Sensor Insert the two connectors, then insert the Ultrasonic Sensor over the connectors, and close the LEGO assembly with the last 3 x 5 beam over the four connector ends it attaches to. 158
Step 15 1x 100 mm Axle Extend the axle through the axle hub until the top of the axle is just below the top of the channel. Remember to tighten the axle hub set screw on the flat side of the axle. 159
Bevel Gear Step 16 2x Bronze Bushing Make sure the bushings do not fall out before or during the next step. For this step and Step 17, hold the robot sideways to keep the bushings from falling out. 160
Note: The Ranger Bot Base uses one 35 cm and one 50 cm cord for the sensors. The Ranger Bot with Bevel Gears needs two 50 cm cords for the sensors. Step 17 1x Ultrasonic Sensor Assembly 2x Axle Set Collar Insert the axle of the Ultrasonic Sensor assembly through the first bushing and then put the first axle set collar on. Slide the axle all the way through the 288 mm channel element and put the second axle set collar on the axle. Before tightening the set collars, slide the axle through the bushings so the bevel gear is resting on the Delrin bearing, slide each set collar up against the bronze bushing above it, and then tighten each set screw to lock each axle set collar. If the bevel gears need to be aligned differently, loosen both set screws to lift the Ultrasonic Sensor assembly enough so that the teeth of the gears are not touching. When reattaching the cord to the Ultrasonic Sensor, do not tangle the cord with other cords or robot parts. The cord must be able to move freely when the Ultrasonic Sensor rotates back and forth. 161
Bevel Gear Final View 162
Wiring Diagram Tighten the screws on the HiTechnic controller after the wires have been inserted. Complete all wiring before attaching the battery. 163