Additive Manufacturing: Tips, Tricks, and Techniques

- [Instructor] 3D printing might enable much lower cost buildings and other structures. However, like any housing fabrication technique using it well requires knowledge, skill, and understanding of what a jurisdiction will sign off on for human habitation. In traditional concrete construction builders make a hollow mold called a form first. Typically this is made out of wood. Concrete is poured into the form and smoothed around any reinforcements. Quite complex shapes can be made this way like this precast concrete stairway. Here we see the mold which is filled with concrete and the final stair. 3D printing allows you to create something that would otherwise have required a mold by laying of similar materials, one layer at a time instead. For example, 3D printers can create most things that can be plastic injection molded. Each 3D print will take longer than making one copy with an injection mold but there's no need to create expensive tooling. - [Man] Concrete can be challenging to work with in any form. Concrete 3D printer is extruded concrete paste that is specifically tuned for 3D printing. Other architectural 3D printers use materials specifically designed just for them. If the concrete is being printed at a building site, rather than a factory the printer needs to be robust and able to handle dirt, dust and other materials being added during the build process. Printers need to be large to be useful. Most have some sort of track rail system that is laid on the ground and a gantry arm that lays down the concrete. Large burners can also be complex to manage, however. Like all 3D printing materials are a critical part of architectural 3D printing. Since the part will be built up layer by layer each layer needs to dry and adhere to the one before it, without the benefit of forms. Installation can be added later. 3D printer company Wasp has been experimenting with printing using locally sourced materials. This might be particularly applicable in areas that have very few resources to make housing. Architectural 3D printing has the promise of being vastly cheaper and faster than a traditional onsite concrete pour. It's a lot easier and cheaper to transport raw materials than it is to move around heavy and delicate concrete objects, for one thing. It also avoids a lot of the labor in traditional home construction using wood or bricks. - [Instructor] For example, manufacturer Mudbox estimates that cost of 3D printing a project on site can be as much as 70% lower than traditionally pouring concrete with similar drops in the time to create a concrete object. Since costs are lower, another benefit is that design elements that might have been cost prohibitive with traditional construction might be affordable. Like most digital manufacturing, however, this increase in speed and cost requires different skills from the traditional methods. A structural engineer is likely to be needed to design the elements to be printed and contractors will need to be proficient in both the nuances of materials used and computerated design programs to create their models. Getting permits signed off for construction with unfamiliar techniques might not be easy either. And users need to have a deep understanding of the letter and spirit of building codes to be able to innovate successfully and safely. - [Man] An alternative way to get past these issues is to do the 3D printing in a factory environment and then ship components to the build site for final assembly. The modular prefab housing industry is a well-established one. Housing components are approved by appropriate regulatory bodies at various levels of government above the local one. Once that happens, it's less of an issue for local permitting agencies to approve an unfamiliar building process than it is for a fully onsite one. Mighty Buildings has taken this approach. This building designed by Ehrlich Yanai Rhee Chaney Architects uses custom design major building panels. These are 3D printed to appropriate sizes in a factory, then assembled onsite. A new standard UL 3401 outline of investigation for 3D printed building construction is being developed for this approach. It covers the printer, the process of printing, materials, quality control and recordkeeping. Printed parts need to be mechanically strong but also have good fire resistance, provide vapor air and water barriers, adequate thermal installation and good indoor air quality. Mighty Buildings components have been the first ones developed under this new standard. Eventually Mighty Buildings would like to 3D print houses or large sections of houses in their entirety. To do that they would first design, slice and 3D print appropriate parts of the structure. They're using a custom large format 3D printer that deposits a proprietary material they call light stone material. After that they can scan the part for defects and add insulating materials to the voids in the pruned walls. Post-processing robots finish off the surface. During the entire process Mighty Buildings uses a variety of sensors to analyze how well the materials are meeting specifications. - [Instructor] Architect Michael Chaney and structural engineer, Patty Harbor Petrovich note other positives of the approach. If a house is being produced many times rather than being built once onsite, the cost of the significant design attention to detail can be amortized over many houses. Since construction costs are forecast to be lower than traditional methods this means a buyer can get the features of a higher end house for an affordable price. 3D printing can also be more sustainable since there's minimal waste in the build process, the materials can be designed for energy efficiency and solar panels can be designed in. 3D printing is in the early stages of its application to large scale architectural elements both in emergency situations and for mainstream housing. It is at the same time, both a very promising technology and one that raises may technical and regulatory challenges. We hope it creates attractive affordable housing for years to come.