Carpentry | EPFL Graph Search

Carpentry is a skilled trade and a craft in which the primary work performed is the cutting, shaping and installation of building materials during the construction of buildings, ships, timber bridges, concrete formwork, etc. Carpenters traditionally worked with natural wood and did rougher work such as framing, but today many other materials are also used and sometimes the finer trades of cabinetmaking and furniture building are considered carpentry. In the United States, 98.5% of carpenters are male, and it was the fourth most male-dominated occupation in the country in 1999. In 2006 in the United States, there were about 1.5 million carpentry positions. Carpenters are usually the first tradesmen on a job and the last to leave. Carpenters normally framed post-and-beam buildings until the end of the 19th century; now this old-fashioned carpentry is called timber framing. Carpenters learn this trade by being employed through an apprenticeship training—normally four years—and quali

Augmented Reality to Facilitate a Conceptual Understanding of Statics in Vocational Education

Lorenzo Lucignano

At the core of the contribution of this dissertation there is an augmented reality (AR) environment, StaticAR, that supports the process of learning the fundamentals of statics in vocational classrooms, particularly in carpentry ones. Vocational apprentices are expected to develop an intuition of these topics rather than a formal comprehension. We have explored the potentials of the AR technology for this pedagogical challenge. Furthermore, we have investigated the role of physical objects in mixed-reality systems when they are implemented as tangible user interfaces (TUIs) or when they serve as a background for the augmentation in handheld AR. This thesis includes four studies. In the first study, we used eye-tracking methods to look for evidences of the benefits associated to TUIs in the learning context. We designed a 3D modelling task and compared users' performance when they completed it using a TUI or a GUI. The gaze measures that we analysed further confirmed the positive impact that TUIs can have on the learners' experience and enforced the empirical basis for their adoption in learning applications. The second study evaluated whether the physical interaction with models of carpentry structures could lead to a better understanding of statics principles. Apprentices engaged in a learning activity in which they could manipulate physical models that were mechanically augmented, allowing for exploring how structures react to external loads. The analysis of apprentices' performance and their gaze behaviors highlighted the absence of clear advantages in exploring statics through manipulation. This study also showed that the manipulation might prevent students from noticing aspects relevant for solving statics problems. From the second study we obtained guidelines to design StaticAR which implements the magic-lens metaphor: a tablet augments a small-scale structure with information about its structural behavior. The structure is only a background for the augmentation and its manipulation does not trigger any function, so in the third study we asked to what extent it was important to have it. We rephrased this question to whether users would look directly at the structure instead of seeing it only through a tablet. Our findings suggested that a shift of attention from the screen to the physical object (a structure in our case) might occur in order to sustain users' spatial orientation when they change positions. In addition, the properties of the gaze shift (e.g. duration) could depend on the features of the task (e.g. difficulty) and of the setup (e.g. stability of the augmentation). The focus of our last study was the digital representation of the forces that act in a loaded structure. From the second study we observed that the physical manipulation failed to help apprentices understanding the way the forces interact with each other. To overcome this issue, our solution was to combine an intuitive representation (springs) with a slightly more formal one (arrows) which would show both the nature of the forces and the interaction between them. In this study apprentices used the two representations to collaboratively solve statics problems. Even though apprentices had difficulties in interpreting the two representations, there were cases in which they gained a correct intuition of statics principles from them. In this thesis, besides describing the designed system and the studies, implications for future directions are discussed.

EPFL2018

Semi-Rigid Moment-Resisting Behavior of Multiple Tab-and-Slot Joint for Freeform Timber Plate Structures

Stéphane Nicolas Roche

Historically based on the transfer of ancestral know-how, the art of carpentry changed considerably at the beginning of the 21st century with the arrival on the market of engineered wood products (EWP) and computer numerically controlled machines (CNC). The development of these wood products was initially started for the needs of aeronautics : lightweight panels but with high structural capacity. It is also in this field that automated multi-axis milling machines and the accompanying computing tool, computer-aided design and manufacturing (CAD / CAM), have begun to be developed to produce more complex mechanical parts. It was also in the early 2000s that several teams of researchers in the field of computer graphics but also in architecture were interested in complex free forms. One of the many challenges is still the discretization with planar elements of doubly curved surfaces oriented freely in space. The encounter of these `` algorithms '' with the high-performant wood panels was ineluctable. However, the assembly of polygonal panels in space to form a structure is not trivial. Optimization efforts are made so that the topology in itself favors the distribution of forces to tend towards a behavior of shells. But the problem is sometimes insoluble for very irregular shapes alternating negative, zero and positive Gaussian curvatures. To ensure the transmission of the axial, shear and bending internal forces induced by vertical or horizontal external loads, whether symmetrical or not, the performance of the assemblies used to connect these panels by their edges becomes paramount. In wood construction, this is a topic currently being studied by a few research laboratories including EPFL for innovative wood-to-wood joints with multiple tab and slots (MTSJ). The main difficulty lies in how to connect thin wood panels with the best stiffness and strength. In the recent past, the assembly of wood parts between them, often with metal fasteners to provide a certain ductility, was assimilated to a hinge. With the new standards like the Eurocodes, the notion of semi-rigidity is now essential to obtain a realistic response of structures to both ultimate and service limit states. The solution proposed at IBOIS enters into this new context. It allows, without glue or metallic connectors, to interconnect thin engineered wood panels, ensuring both locator and connector features and the transfer of multidirectional forces. This thesis focuses on the semi-rigid moment resisting behavior of the through tenon variant (TT) with closed slots. The numerous experiments conducted during this study demonstrated the ability of this variant to compete with screws to resist a moment around the angularly connected edges. The joint is directly generated during the multiaxial cutting of laminated veneer lumber(LVL) panels which include a certain percentage of cross-layers. From a structural point of view, the local mechanical study under a bending moment was inspired by a wood-to-wood joint in service in the ancestral Japanese shrines, the "Nuki" joint. Analyzed by Japanese researchers as it historically participates in the resilience of their ancestral constructions to typhoons and earthquakes, it activates embedment mechanisms of wood in rotational partial compression (RPC) to resist the moment resulting from the external loads. It is these mechanisms that are taken into account for through tenon variant. ...

EPFL2017

Augmented-reality-assisted timber drilling with smart retrofitted tools

Julien Gamerro, Andrea Settimi, Yves Weinand

An ordinary electric drill was integrated into a context-aware augmented reality (AR) framework to assist in timber-drilling tasks. This study is a preliminary evaluation to detail technical challenges, potential bottlenecks, and accuracy of the proposed object- and tool-aware AR-assisted fabrication systems. In the designed workflow, computer vision tools and sensors are used to implement an inside-out tracking technique for retrofitted drills based on a reverse engineering approach. The approach allows workers to perform complex drilling angle operations according to computer-processed feedback instead of drawing, marking, or jigs. First, the developed methodology was presented, and its various devices and functioning phases were detailed. Second, this first proof of concept was evaluated by experimentally scanning produced drillings and comparing the discrepancies with their respective three-dimensional execution models. This study outlined improvements in the proposed tool-aware fabrication process and clarified the potential role of augmented carpentry in the digital fabrication landscape.