Large Scale 3D Printing and Toolpath Optimization

2017 Research

w/ Cameron Wu

GeoSurf

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GeoSurf

 

A modified over-sized 3D printer allow this full-size (5'9") surfboard to be printed in one single run. The board is fully parametrically defined to enable a transition between different board profile and structural pattern, which could be easily adjusted for different surf style.

A surfboard undergoes different stress and load in action. A conventional monolithic foam board ignores the heterogenous distribution of stress. A smooth differentiation of pattern density can distribute bending strengthen across the board surface. The density of the pattern could be determine by topological optimization, resulting in a desirable bending behavior. The interior pattern weave between the top and bottom surface of the board, forming a lightweight sandwiched structure. Being 3D printed, it also allowed variation in angle that create internal triangulation resulting in varying degree of rigidity.

A new tool path algorithm is implemented for the printing of this surf board. The new tool path provide a continuous, single tool path for the entire board. This eliminates all non-print move and generally improve printing reliability and speed. It greatly improve finish quality with aligned parameter and print direction.

Geometry

Structural Analysis

Pattern Distribution

Internal Structure

Custom Slicer

Variable print speed, width and support column

Continuous toolpath

Geometry to print

Typical toolpath with travel

5. Outer perimeter

2. Coils back

3. Complete opposite infill

4. Complete infill

1. Infill starts

A custom C# grasshopper component was developed for the project. The component takes in information regarding each via point, namely the [x,y,z]location, print speed and print width, and export the gcode in the format of string text. Speed and print width is modify in the grasshopper script to provide varying parameter on different parts of the print. 

For a large scale print job like this, additional functionality is added. The “reduce speed” parameter slows down the print speed as z height increases. This reduce vibration of the printer due to rapid movement. The “Turning Threshold” parameter would cause the nozzle to stop momentarily(>0.01s) at sharp corner and significantly improving corners sharpness when printing with large diameter nozzle.
 

Irregular surface finish due to sporadic print direction. Rough contour due to travel jerk. Sliced on Simplified 3D.

Improved surface finished and consistency

Raft and support