The first robot, the Base Robot, lays down the first ten layers of material to create a foundation footprint. Sensors mounted inside the robot control direction, following a predefined path. Traveling in a continuous path allows for a vertical actuator to incrementally adjust the nozzle height for a smooth, continuous, spiraling layer. The advantage of laying material in a continuous spiral is that it allows for constant material flow, without having to
move the nozzle up at intervals of one layer.
The foundation robot size 26*35*37 cm, weights 2.05kg.
Tools and materials:
-Waterjet aluminum gears
-Laser cut acrylic
-Motor, Axle and wheel mount (aluminum or 3d printed)
-4mm metal shaft
The base robot is mobile, with a vertical CNC moving the nozzle up in Z, incrementally while the robot moves along a predefined path. This creates a continuous spiraling toolpath for the nozzle laying the material on top of each layer previously printed.
All the three robots make use of Makerbeams for their frames, giving flexibility within the prototyping process. Makerbeams are reusable and relatively easy to adjust using the T-slot bolt system. The CNC is also made using the makerbeam bearing kit. You can learn from projects listed here.
The connection between the wheels, chassis and motors is simple using a bearing to support the wheel shaft attached with self locking nuts. The stability of the shaft is reliant on the size and spacing of the bearing set. This solution created a more stable platform for printing than a soft suspension system.
For the robot to follow the predetermined path we used a basic QTR-8RC reflectance sensor array. This allows the robot to follow a predefined path. When testing outside we found that the sensor would lose the track of its path under strong direct sunlight. The simple solution we found to this was to shade the sensor from the sun.
The Arduino and Processing file can be found in step 4 software section.