Conventional methods of 3d printing require planar contouring, with filament deposited from above using gravity. Structure must exist below the actively printed layer, and printed filament can’t span far between vertical support. This methodology has serious implications for the speed and efficiency of geometries with horizontal spans. Further, this gravity dependent contouring means that the final layup of the anisotropic material is not optimized for structural design. The aim of 4 Axis Printing is to overcome conventional 3d printer limitations in overhangs through actively rotating the bed, in a feedback loop, to assist a non-planar 3d printing process. This allows for the printing of horizontal spans, without the need for support structures underneath.
We set out to develop a method for a 3d printer bed that rotates in a feedback loop with the 3d printer itself. This allows for a fluid and continuous interplay in which the printer can deposit filament while a motor rotates the bed for an optimal printing angle. The hardware for the bed rotation was designed using a single motor. The stepper motor rotates a vertical spindle that is translated into rotational movement using a slotted pin connection. This type of connection provides translation in the x direction, and rotation about the y axis. The motor is controlled using an arduino.
Given a desired cantilever geometry, we generate a g-code that is better suited for non-planar printing than standard contouring. The print path is fed into a communication gate between the printer and the rotating bed. The path is assessed for being of a suitable angle to the nozzle for 3d printing, if it is not, then the bed is instructed to rotate to a Safe Angle. The motor then sends a serial to the communication gate to signify that it has completed the bed rotation. Then, the communication gate tells the 3d printer to resume the print until the print path lies outside of a Safe Angle. The communication gate is facilitated by grasshopper for Rhino. The information from the motor flows in from a single serial port. The plug-in Firefly is used to bring the serial information into grasshopper. The communication gate then instructs the 3d printer to continue printing when the motor has completed its motion. In this way, grasshopper functions as a central hub for all of the information to be received and distributed to the constituent parts. The motor for the bed actuation, and the 3d printer need to be in a feedback loop such that each can understand when the other has completed it’s respective task.
Our final proof of concept was a curvilinear cantilever structure. As the 3d printer proceeded, the bed was continually rotated such that the print path was normal to the 3d print nozzle. This enabled the production of our cantilever structure without any support structure. This proved that the feedback loop was working between the bed actuator and the 3d printer. It also displayed that our system was calibrated enough to print the structure with decent resolution.
We conducted several printing tests to evaluate the efficacy of our system. One test was printing higher resolution textural finishes to see how precise we could print. We decided to print a series of vases, each with a varying degree of textural intensity. Although our system does not produce perfect results, it does have a high enough fidelity for textural variation.
The smooth texture best exemplies the errors of our system. This is mostly due to calibration issues between the generated code and the steps of the spindle motor. Given more time to refine the code and hardware design, we are confident that the system could produce perfect smooth texture.
The loop texture, having an aesthetic of ordered randomness, seems to not be adversely affected by the slight inaccuracies of the tilting print bed. The rotating printer bed is accurate enough to print this texture, and the texture seems to hide many of the imperfections.