Parametric Computer-aided design (CAD) enables the creation of reusable models by integrating variables into geometric properties, facilitating customization without a complete redesign. However, creating parametric designs in programming-based CAD presents significant challenges. Users define models in a code editor using a programming language, with the application generating a visual representation in a viewport. This process involves complex programming and arithmetic expressions to describe geometric properties, linking various object properties to create parametric designs. Unfortunately, these applications lack assistance, making the process unnecessarily demanding. We propose a solution that allows users to retrieve parametric expressions from the visual representation for reuse in the code, streamlining the design process. We demonstrated this concept through a proof-of-concept implemented in the programming-based CAD application, OpenSCAD, and conducted an experiment with 11 users. Our findings suggest that this solution could significantly reduce design errors, improve interactivity and engagement in the design process, and lower the entry barrier for newcomers by reducing the mathematical skills typically required in programming-based CAD applications
https://doi.org/10.1145/3654777.3676417
We introduce Rhapso, a 3D printing system designed to embed a diverse range of continuous fiber materials within 3D objects during the printing process. This approach enables integrating properties like tensile strength, force storage and transmission, or aesthetic and tactile characteristics, directly into low-cost thermoplastic 3D prints. These functional objects can have intricate actuation, self-assembly, and sensing capabilities with little to no manual intervention. To achieve this, we modify a low-cost Fused Filament Fabrication (FFF) 3D printer, adding a stepper motor-controlled fiber spool mechanism on a gear ring above the print bed. In addition to hardware, we provide parsing software for precise fiber placement, which generates Gcode for printer operation. To illustrate the versatility of our system, we present applications that showcase its extensive design potential. Additionally, we offer comprehensive documentation and open designs, empowering others to replicate our system and explore its possibilities.
We present Speed-Modulated Ironing, a new fabrication method for programming visual and tactile properties in single-material 3D printing. We use one nozzle to 3D print and a second nozzle to reheat printed areas at varying speeds, controlling the material's temperature-response. The rapid adjustments of speed allow for fine-grained reheating, enabling high-resolution color and texture variations. We implemented our method in a tool that allows users to assign desired properties to 3D models and creates corresponding 3D printing instructions. We demonstrate our method with three temperature-responsive materials: a foaming filament, a filament with wood fibers, and a filament with cork particles. These filaments respond to temperature by changing color, roughness, transparency, and gloss. Our technical evaluation reveals the capabilities of our method in achieving sufficient resolution and color shade range that allows surface details such as small text, photos, and QR codes on 3D-printed objects. Finally, we provide application examples demonstrating the new design capabilities enabled by Speed-Modulated Ironing.
https://doi.org/10.1145/3654777.3676456
In this paper we present Travel Reduction Algorithm (TRAvel) Slicer, which minimizes travel movements in 3D printing. Conventional slicing software generates toolpaths with many travel movements--movements without material extrusion. Some 3D printers are incapable of starting and stopping extrusion and it is difficult to impossible to control the extrusion of many materials. This makes toolpaths with travel movements unsuitable for a wide range of printers and materials. We developed the open-source TRAvel Slicer to enable the printing of complex 3D models on a wider range of printers and in a wider range of materials than is currently possible. TRAvel Slicer minimizes two different kinds of travel movements--what we term Inner- and Outer-Model travel. We minimize Inner-Model travel (travel within the 3D model) by generating space-filling Fermat spirals for each contiguous planar region of the model. We minimize Outer-Model travel (travels outside of the 3D model) by ordering the printing of different branches of the model, thus limiting transitions between branches. We present our algorithm and software and then demonstrate how: 1) TRAvel Slicer makes it possible to generate high-quality prints from a metal-clay material, CeraMetal, that is functionally unprintable using an off-the-shelf slicer. 2) TRAvel Slicer dramatically increases the printing efficiency of traditional plastic 3D printing compared to an off-the-shelf slicer.
https://doi.org/10.1145/3654777.3676349
One of the core promises of parametric Computer-Aided Design (CAD) is that users can easily edit their model at any point in time. However, due to the ambiguity of changing references to intermediate, updated geometry, parametric edits can lead to reference errors which are difficult to fix in practice. We claim that debugging reference errors remains challenging because CAD systems do not provide users with tools to understand where the error happened and how to fix it. To address these challenges, we prototype a graphical debugging tool, DeCAD, which helps comparing CAD model states both across operations and across edits. In a qualitative lab study, we use DeCAD as a probe to understand specific challenges that users face and what workflows they employ to overcome them. We conclude with design implications for future debugging tool developers.
https://doi.org/10.1145/3654777.3676353