Step One: Transmission Axles.
- At a height of two flat plates from the base, mount two transmission axles that will take the rotation from the A and B motors in the Boost block to the two bender arms at the front of the machine. The mechanism needs four 1 x 2 perforated blocks, four stoppers (half or full length doesn't matter) and eight plates to achieve the required height. Also, the user needs four bevel gears. It doesn't matter if the user uses the newer 12-tooth version or the older 14-tooth version, but make sure they have a matching gear for each one they use. The final build needs four matching pairs of these bevel gears. For this product, the contestants used three 12-tooth pairs and one 14-tooth pair. The distance between the two transmission assemblies is 6 studs. This area needs to be kept free for now.
Step Two: Supports for Later Components.
- Using regular (non-Technic) Lego bricks, the user builds a couple of supports for the rest of the robot. Note that the perforated 2 x 4 plates will connect the two base plates together. There's no functional reason for those to be perforated.
Step Three: Walls for the Feeder.
- Using perforated bricks (mainly 1 x 6), the user constructs side walls to mount the feeder wheels between. The total height is a full number of regular bricks, but the contestants split one into three plates, to push the two feeder wheels onto each other. That is also the reason why they have the perpendicular beam: without that beam the forces on the wheels push the wall apart.
- Note: The external Boost motor will connect to those, and the wheel axle driven directly by the motor goes in between the two connectors.
Step Four: Feeder Wheels and Rear Alignment Tubes.
- The contestants chose Lego wheels that have a compressible rubber tire on a central rim. This allows for pressure to be exerted by pressing the wheels together a bit. The pipe cleaner will be fed between the two wheels, one wheel will be motor-driven, and the other wheel will be driven by its firm contact with the first wheel.
- They also used a 180-degree axle and pin connectors as alignment tubes. The three rear alignment tubes are centered by pins on one side, and by axles on the other side. The axles protrude from the wall on the other side, which allows the user to fixate them in a permanent direction. The only part that has three fixed axle attachments in a row is the grey egg-shaped part. The user could reduce the construction to two alignment pieces, and use a piece with two fixed axle attachments instead.
- Note: Using pins on both sides allows the alignment tubes to rotate. Also, note that the space between the walls is one unit wider than the black tube parts. This is why half-unit spacers are added on both sides.
Step Five: Assembly.
- The wheel on the longest axle is the one driven by the motor, so it is positioned between the grey pins that will keep the motor in place later. It doesn't need additional stoppers, as the connection in the motor is rigid enough. The other wheel is on the shorter axle and is kept in place by two half stoppers on either side of the walls.
- The alignment tubes are mounted in the dark grey brick in the example. The designer can see the egg-shaped fixating piece on one side, keeping the alignment tubes oriented correctly.
- For the type of wheels that the contestants chose, the one plate below/two plates above positioning of the dark grey brick aligns the tubes with the contact surface between the wheels.
Step Six: Main Beam and Transmission Gear Prep.
- At the front of the robot, one long beam (15 holes) supports the front alignment tube, the bender axles and the transmission gears. Three 1/3th height beams are added to either reduce the freedom of movement of the axles or to fixate the orientation of an axle. They are held in place by pins. Many of the other holes in the beam will be used in the next steps, so if the user uses 1/3th height beams of different length, that may cause issues later.
Step Seven: Main Beam Axles, and Bender Arms.
- In this step, various items are assembled that go into the main front beam. The first is the front alignment tube. It consists of two axles, an alignment tube identical to the ones we used at the back, and a single-ended connector that keeps the pipe cleaner precisely centered. This one goes into the central hole of the main beam. In the previous step, a piece was added that prevents rotation in that position. This is crucial for the alignment tube.
- Secondly, the benders are assembled. One bender arm consists of a 4 x 2 elbow beam, a connector, and a small rim. Two arms are made. These go on long axles, and into holes two steps away from the central hole.
- At the bottom of the bender axles, 24-tooth gears are attached. The short axles from the previous step get 8-tooth gears and a matching bevel gear for the transmission axle. Note that the 1:3 gear reduction provides extra force for the bender arms. Two 16-tooth gears cover the same distance but didn't bend the pipe cleaners reliably during testing.
Step Eight: Main Beam Attachments.
- Using two pins, an axle pin, a perforated 1 x 2, and a piece called "Axle and Pin Connector Perpendicular 3L with 2 Pin Holes" on each end, the user ensures the beam is firmly attached to the rest of the structure. There are perpendicular attachment pieces with only 1 hole. Those will work as well, but the contestants saw that the movement of the bender arms exerts a lot of force on the construction, so the user will prefer using the 2-pin hole variant.
Step Nine: Upper Beam.
- The movement of the bender arms is crucial, and a lot of force is transferred onto the axles and their support. Therefore, the user wants to mount an upper beam that provides an additional pivot point for the bender axles. The contestants used a 9-hole beam. Holes 3, 5 and 7 are occupied by axles. This leaves the outermost two holes for mounting the beam. The contestants used a part called "Axle and Pin Connector Perpendicular 3L with Center Pin Hole" on one side, but couldn't find a second identical one, so they went for the shorter "Axle and Pin Connector".
Step Ten: Mounting the Beam and Bender Assembly.
- The main and upper beams can now be mounted onto the existing structure. Careful alignment of the bevel gears is needed, so the transmission axles don't block each other. Horizontal alignment of the bender rims with the feeder tube is also needed.
Step Eleven: Reinforcing the Structure.
At the four attachment points of the beams, the user adds reinforcement using regular bricks. Take care not to hinder the movement of the axles, wheels, and bender arms.
Step Twelve: Attach External Boost Motor.
- The attachment points for the external boost motor are already in place, so attaching it should now be straightforward. The motor can be added in four different orientations. Functionally for the motor itself doesn't matter, but the contestants preferred the orientation that leaves the most swing-room for the bender arm on that side.
Step Thirteen: Attach the Boost Motor Block.
- The creator builds two hind legs for the Boost motor block and attaches bevel gears on short axles on both the A and B motors. They mount the front of the motor block on the second base plate. This leaves the battery compartment reachable at the bottom. After joining the two base plates, the user aligns the bevel gears so the A and B motors drive the transmission axles and the bender arms.
Step Fourteen: Create a Program in the Boost App.
- Once the robot is finished, it is time to fire up the Boost app. Start experimenting with the feeder speed, the bender arm range, etcetera. The contestants created programs to bend a 5-point star, a heart, a circle, a plus sign, and a diamond shape. They used pipe cleaners of 6-millimeter diameter and 30-centimeter lengths.