LaserFactory is an integrated fabrication process that augments a commercially available fabrication machine to support the manufacture of fully functioning devices without human intervention. In addition to creating 2D and 3D mechanical structures, LaserFactory creates conductive circuit traces with arbitrary geometries, picks-and-places electronic and electromechanical components, and solders them in place. To enable this functionality, we make four contributions. First, we build a hardware add-on to the laser cutter head that can deposit silver circuit traces and assemble components. Second, we develop a new method to cure dispensed silver using a CO2 laser. Third, we build a motion-based signaling method that allows our system to be readily integrated with commercial laser cutters. Finally, we provide a design and visualization tool for making functional devices with LaserFactory. Having described the LaserFactory system, we demonstrate how it is used to fabricate devices such as a fully functioning quadcopter and a sensor-equipped wristband. Our evaluation shows that LaserFactory can assemble a variety of differently sized components (up to 65g), that these can be connected by narrow traces (down to 0.75mm) that become highly conductive after laser soldering (3.2Ohm/m), and that our acceleration-based sensing scheme works reliably (to 99.5% accuracy).
Designers of machine-cut objects must often consider whether and how their design can be fabricated with their available materials. In contrast to tools that support preparing finished designs for fabrication, we investigate shortening the feedback loop between design creation and fabrication preparation. To this end, we present Fabricaide, a fabrication-aware tool that interleaves the processes of creating and preparing designs for fabrication. By providing live feedback on how parts should be placed onto material sheets, analyzing how much material is consumed, and alerting users when designs are infeasible, Fabricaide enables users to proactively tailor their design to their available material. Fabricaide achieves this with a custom packing algorithm that arranges parts onto material sheets at interactive speeds. Our qualitative user study shows how Fabricaide can support different workflows, encourage material-conscious design practices, and provide insights on how to further improve similar interfaces in the future.
We present a software system for fused deposition modelling 3D printing that replaces infill material with scrap to reduce material and energy consumption. Example scrap objects include unused 3D prints from prototyping and calibration, household waste like coffee cups, and off-cuts from other fabrication projects. To achieve this, our system integrates into an existing CAD workflow and manages a database of common items, previous prints, and manually entered objects. While modelling in a standard CAD application, the system suggests objects to insert, ranked by how much infill material they could replace. This computation extends an existing nesting algorithm to determine which objects fit, optimize their alignment, and adjust the enclosing mesh geometry. While printing, the system uses custom tool-paths and animated instructions to enable anyone nearby to manually insert the scrap material.
ChromoUpdate is a texture transfer system for fast design iteration. For the early stages of design, ChromoUpdate provides a fast grayscale preview that enables a texture to be transferred in under one minute. Once designers are satisfied with the grayscale texture, ChromoUpdate supports designers in coloring the texture by transitioning individual pixels directly to a desired target color. Finally, if designers need to make a change to the color texture already transferred, ChromoUpdate can quickly transition individual pixels from one color to a new target color. ChromoUpdate accomplishes this by (1)~using a UV projector rather than a UV LED, which enables pixels to be saturated individually rather than resetting the entire texture to black, and (2)~providing two new texture transfer algorithms that allows for fast monochromatic previews and color-to-color transitions. Our evaluation shows a significant increase in texture transfer speed for both the monochromatic preview(831%) and color-to-color updates(29%).
Simulation offers many advantages when designing analog circuits. Designers can explore alternatives quickly, without added cost or risk of hardware faults. However, it is challenging to use simulation as an aid during interactive debugging of physical circuits, due to difficulties in comparing simulated analyses with hardware measurements. Designers must continually configure simulations to match the state of the physical circuit (e.g. capturing sensor inputs), and must manually rework the hardware to replicate changes or analyses performed in simulation. We propose techniques leveraging instrumentation and programmable test hardware to create a tight coupling between a physical circuit and its simulated model. Bridging these representations helps designers to compare simulated and measured behaviors, and to quickly perform analytical techniques on hardware (e.g. parameter-response analysis) that are typically cumbersome outside of simulation. We implement these techniques in a prototype and show how it aids in efficiently debugging a variety of analog circuits.
With the recent interest in wearable electronics and smart garments, digital fabrication of sensing and interactive textiles is in increasing demand. Recently, advances in digital machine knitting offer opportunities for the programmable, rapid fabrication of soft, breathable textiles. In this paper, we present KnitUI, a novel, accessible machine-knitted user interface based on resistive pressure sensing. Employing conductive yarns and various machine knitting techniques, we computationally design and automatically fabricate the double-layered resistive sensing structures as well as the coupled conductive connection traces with minimal manual post-processing. We present an interactive design interface for users to customize KnitUI's colors, sizes, positions, and shapes. After investigating design parameters for the optimized sensing and interactive performance, we demonstrate KnitUI as a portable, deformable, washable, and customizable interactive and sensing platform. It obtains diverse applications, including wearable user interfaces, tactile sensing wearables, and artificial robot skin.
Fabricating 3D printed electronics using desktop printers has become more accessible with recent developments in conductive thermoplastic filaments. Because of their high resistance and difficulties in printing traces in vertical directions, most applications are restricted to capacitive sensing. In this paper, we introduce Thermoformed Circuit Board (TCB), a novel approach that employs the thermoformability of the 3D printed plastics to construct various double-sided, rigid and highly conductive freeform circuit boards that can withstand high current applications through copper electroplating. To illustrate the capability of the TCB, we showcase a range of examples with various shapes, electrical characteristics and interaction mechanisms. We also demonstrate a new design tool extension to an existing CAD environment that allows users to parametrically draw the substrate and conductive trace, and export 3D printable files. TCB is an inexpensive and highly accessible fabrication technique intended to broaden HCI researcher participation.
In this paper, we propose the designs for low cost and 3D-printable add-on components to adapt existing breadboards, circuit components and electronics tools for users with blind or low vision (BLV). Through an initial user study, we identified several barriers to entry for beginners with BLV in electronics and circuit prototyping. These barriers guided the design and development of our add-on components. We focused on developing adaptations that provide additional information about the specific component pins and breadboard holes, modify tools to make them easier to use for users with BLV, and expand non-visual feedback (e.g., audio, tactile) for tasks that require vision. Through a second user study, we demonstrated that our adaptations can effectively overcome the accessibility barriers in breadboard circuit prototyping.
In this paper, we present a metamaterial structure called thermoformable cells, TF-Cells, to enrich thermoforming for post-print modification. So far, thermoforming is limitedly applied for modifying a 3D printed object due to its low thermal conductivity. TF-Cells consists of beam arrays that affluently pass hot air and have high heat transference. Through heating the embedded TF-Cells of the printed object, users can modify not only the deeper area of the object surface but also its form factor. With a series of technical experiments, we investigated TF-Cells’ thermoformability, depending on their structure’s parameters, orientations, and heating conditions. Next, we present a series of compound cells consisting of TF-Cells and solid structure to adjust stiffness or reduce undesirable shape deformation. Adapting the results from the experiments, we built a simple tool for embedding TF-Cells into a 3D model. Using the tool, we implemented examples under contexts of mechanical fitting, ergonomic fitting, and aesthetic tuning.
We present assembler^3 a software tool that allows users to perform 3D parametric manipulations on 2D laser cutting plans. Assembler^3 achieves this by semi-automatically converting 2D laser cutting plans to 3D, where users modify their models using available 3D tools (kyub), before converting them back to 2D. In our user study, this workflow allowed users to modify models 10x faster than using the traditional approach of editing 2D cutting plans directly. Assembler^3 converts models to 3D in 5 steps: (1) plate detection, (2) joint detection, (3) material thickness detection, (4) joint matching based on hashed joint "signatures", and (5) interactive reconstruction. In our technical evaluation, assembler^3 was able to reconstruct 100 of 105 models. Once 3D-reconstructed, we expect users to store and share their models in 3D, which can simplify collaboration and thereby empower the laser cutting community to create models of higher complexity.
We present fastForce, a software tool that detects structural flaws in laser cut 3D models and fixes them by introducing additional plates into the model, thereby making models up to 52x stronger. By focusing on a specific type of structural issue, i.e., poorly connected sub-structures in closed box structures, fastForce achieves real-time performance (10^6x faster than finite element analysis, in the specific case of the wheelbarrow from Figure 1). This allows fastForce to fix structural issues continuously in the background, while users stay focused on editing their models and without ever becoming aware of any structural issues.
In our study, six of seven participants inadvertently introduced severe structural flaws into the guitar stands they designed. Similarly, we found 286 of 402 relevant models in the kyub  model library to contain such flaws. We integrated fastForce into a 3D editor for lasercutting (kyub) and found that even with high plate counts fastForce achieves real-time performance.
We propose a novel design of engineered, structured materials that leverages fast fabrication technologies, pushing them towards mass-fabrication.
Specifically, our metamaterial is designed to be laser cut, to approximate the volumetric shape and allow for locally varying compliance.
Traditional mechanical metamaterials consist of intricate cells arranged on a 3-dimensional grid, limiting them to 3D printing -- which is slow.
Our metamaterial is designed for laser cutting, which is drastically faster.
Our structures are best described as ruffled strips of thin sheet material, such as paper, plastics, metals, etc.
Users can interactively define the ruffles' anisotropic stiffness directions and local density. Our computational design tool assists users by automatically optimizing the ruffle to fill the shape's volume, and exporting the flat ruffle design ready for cutting.
We demonstrate how such ruffled metamaterials can be utilized for, e.g., custom toys with locally varying compliance, custom packaging material, or lightweight formwork for architectural shells.