Introduction: Active Rest
Welcome to our instructable for Active Rest, a multivalent street sculpture that was selected to help activate San Francisco's urban streetscape during the 2015 Market Street Prototyping Festival.
Overall, Active Rest seeks to play a number of different roles: sculpture, climbing wall, performance backdrop, beacon, along with a veiled inner space for rest, reflection, or temporary privacy. As the duality in the name implies, we sought to create a piece that can programmatically capture both ends of the spectrum of human activity, thus driving more use and more engagement amongst what we hope is a wide cross section of the city's populace.
In this instructable we will give you a recap of our experience designing, fabricating and installing this piece, as well as to offer some tips and direction so that you can create your own rapidly-deployable, highly-enjoyable street structure of play, respite, and wayfinding.
To start, take a look at our video here to get a quick visual introduction...
Step 1: Design: Overall Massing
Active Rest was designed in three phases: overall massing was developed using horizontal strata as an organizing concept, structural development that factors gravity and lateral forces, and fabrication optimization which developed the graphical tools for understanding how the many pieces would be assembled once created.
We wanted to create an installation you can play with. Campusing, which is a method of training for climbers, was the perfect solution. It’s intuitive. It’s informal. You don’t need special equipment to do it.
To generate the overall form, we utilized Kangaroo, a Grasshopper plugin for Rhino3D. The overall massing was generated using catenary curves that evoke geomorphic origins. We had previously explored ideas on whether the structure could have dual functions and decided to have one side cater to a more active engagement and the second to a more passive, seating and resting strategy. As the form began to take shape, each side began to resemble its own kind of crescent in cross-section; together the “active” crescent and the “rest” crescent slung into one another, supporting each other while also introducing a visually playful precariousness.
Each iteration of the design looked at ways to leverage campusing activities in tandem with space for sitting and introspection, all captured within what is a self-supporting sculpture. We were adamant that the installation should not look like a campusing wall or a bench, but rather should entice a passerby to be curious, to explore, and to ultimate engage.
Step 2: Design: Structural Development
With the overall massing established, we next focused on bringing the weight down. Initial tests had the installation weighing over 8 tons, which would have crushed the concrete it would sit on. Strategically, we removed infill layers, which reduced the overall weight while also presenting new opportunities to give Active Rest additional graphic interest in elevation.
The remaining intact layers became known as strata. We determined the spacing of infill to strata by looking at common gaps that are frequently used on traditional campusing boards. We settled on a ratio of 1 wood strata to 3 gap heights. Aside from reducing the weight, this also introduced a graphically-charged visual permeability to the structure. Remaining areas of solid infill become structural zones for fastening the infill and strata layers together. The form was refined extensively in Grasshopper and in Rhino to accentuate the difference between the active and rest crescents.
As our structural approach became more clear, we were very fortunate to get to bounce ideas off of engineers with Livermore Architecture & Engineering, along with the San Francisco branch of ARUP, possibly the most renowned structural engineering firm in the world.
To make sure that strata didn’t bow when grabbed while campusing, we doubled up the sheets on areas that were intended to be climbed on. Due to on-site time constraints and potential base shear problems, we steered away from the threaded rod structural approach and instead proceeded with the screw approach (refer to the materials section to learn more). In the end we developed an overlaying pattern that would result in a similar structural performance to the threaded rods. It should also be mentioned that we believe the threaded rod approach can still work and would present the most reusable method for installing Active Rest, it just proved to be an infeasible method for this round of prototyping.
Step 3: Materials
Active Rest is primarily composed of 120 sheets of 4’-0”x8’-0”x1/2” plywood, digitally cut with a (computer numerical controlled) CNC mill and assembled with a steel substructure. This substructure can be made with either threaded rod or lag screws.
The threaded rod structural system employs (10) 10’-0” lengths of ¾” threaded rod that is deployed within the plywood using precut holes. Each side of the rod lengths receives a washer and nut to tighten each end, pulling the wood into compression and the steel rod into tension. The alternative method for structuring Active Rest uses approximately 1,000 #8x3/4” screws for preassembling the individual plywood pieces into larger 4-layer modules. Each of these modules is then assembled in place onsite using approximately 2,500 #10x4” lag screws. All screws should be stainless steel if being used outside.
Screwing the large modules together typically requires piloting holes for the screws first to reduce stripping. These tools require an onsite electricity source, whether by direct plug or generator. Overall, the lag screw structural option does present some conveniences but also can be more time intensive and limits reuse since increasingly larger screws must be used at the beginning of each new lifecycle.
Other consumables that you may find helpful to create your own riff on Active Rest include: CNC mill bits: ¼” bits work best for large cuts, while ⅛” or even 1/16” bits work well for carving text. Bits wear down over time, so you’ll need at least 2 of each. markers for writing down ID system for each fabricated piece sandpaper to smooth edges of each piece; 60 grit works well overall, though higher grits can be used to further smooth the edges. drill bits for piloting holes if you plan to use the screw approach for the substructure; bits should be ⅛” smaller in diameter to ensure sufficient bite for the screws that will follow stain and polyurethane if you plan to finish the plywood and prepare it for outdoor use Beyond at least one CNC mill, you’ll need include these tools: multiple crescent wrenches and vice grips if the threaded rod approach is used for preassembly and installation multiple impact drivers and/or drills if screws are used instead (remember these need access to electricity for charging batteries or directly plugging into service)
Step 4: Design: Fabrication Optimization
With the overall design firmly developed, the last design phase consisted of getting the model ready for fabrication. By this stage, we had a good group of volunteers who were eager to help out. Getting the model ready for the CNC mill proved to be a lot of manual steps. We labored over how to organize the model for fabrication. We decided on 5 different classifications: active strata, rest strata, active infill, rest infill, and cross ties that join both crescents together. With 1500+ unique components, the goal was to be able to quickly organize the pieces as they came off the mill and to be able to sort them in a rational system.
Once we had the final model “ready to go,” we used another grasshopper plugin, RhinoNest to organize the model into a series of slices that fit on our standard 4’-0"x8’-0" plywood sheets. We experimented with how to organize the nesting. We considered the model as a whole, each crescent seperately, and the model as by thirds. Due to time, material and budget constraints, we decided to nest the model as a whole onto the sheets. Much like cookie-cutting, we optimized the nesting settings to minimize the amount of wasted material as much as possible.
In terms of assembly, since we decided to pursue the structural system using screws, we also developed a screwing template that could be used in the field to ensure proper edge spacing between screws was being maintained. This template also helps to ensure that as each successive layer is installed, screws are not drilled on top of one another.
Step 5: Fabrication
Active Rest requires an intensive upfront fabrication process, which then fortunately gives way to relatively rapid onsite installation, as well as equally quick disassembly and redeployment. The optimized 3D model that was digitally created in the design phase is now distilled into a series of 2D patterns that depict each of the pieces of plywood that compose this model. A design plug-in called RhinoNest can be used to pack the 1,500 individual 2D CAD patterns onto as few plywood sheets as necessary, to optimize material use and reduce waste. In total, Active Rest requires 120 sheets of 4’-0”x8’-0”x1/2” sheets of plywood. Each sheet is digitally cut with its own 2D CAD file, one at a time, using a CNC mill. For Active Rest, we utilized two different Shopbots (CNC mills), the first at the Architecture department at the Academy of Art University and the second at TechShop in San Francisco.
The Shopbot at the Academy of Art was set up using a router head and a vacuum bed which helped the plywood stay in place when milling. We also used clamps to help with any bowing of the sheets as well as placed strategically screws throughout the board. Due to the router, rather than a spindle driving the endmill, we were averaging about 45 minutes to cut approximately 15 to 18 pieces from a sheet. The Shopbot at Techshop was set up a little different, having a Spindle driving the endmill and no vacuum bed. To get the sheets to adhere to the bed we used special polymer nails that would hold the wood in place until you applied a shear force to the wood after the cutting process using a hammer or mallet.
After the pieces were cut, we labeled each piece with an alpha numeric which allowed us to sort and assemble them more efficiently. Each piece was also hand sanded to ensure that edges were rounded and user-friendly overall. Total fabrication time, averaging 8 hours of single machine operation per day, lasted 10 days.
Step 6: Assembly
Preassembly of the strata and infill layers into 4-layer modules was accomplished off site, following axonometric assembly drawings and using #8x2" screws. Preassembling the pieces saved valuable onsite time by turning 1,500 individual pieces into 98 easily identifiable building blocks. These modules were organized into three groups: the Active side, the Rest side, and the cross braces that spanned between both sides to laterally hold the entire installation together.
We rented a 10’ truck to transport all of the pre-assembled modules to the install site. (We had to be careful with how much weight we loaded into the truck and could not load the whole project at once because it would have pushed the load capacity.)
Once all pieces were onsite, one person instructed which numbered piece came next. We had at least two people verifying each layers’ placement before we secured them in place. Each piece was secured into place with a #10x4” deck screws by piloting holes with a 3/32" screw bit using corded drills (which possess more power than battery-operated drills).
Active Rest was built overnight on Market Street on April 8, 2015 and as dawn broke on April 9th, a new spectacle was born on the streetscape...
Step 7: Interaction
Diverse offerings are the best ways to appeal to a diverse audience. Since Active Rest has the ability to be a climbing wall, a meditative enclosure, a performance backdrop, a beacon, a spectacle, a seat on the street, or even a seat in the trees, it is an open invitation to many different kinds of people. This variety of use coupled with its large presence on the street definitely garnered lots of interest and interaction while it was installed from April 9-11, 2015.
Children were, of course, very excited by the towering oddity of Active Rest, with many questions to their parents about what it was and if they could climb on it or go inside it. What was especially fantastic though, was that adults of all kinds and abilities came up to either climb on the piece or crawl inside. Sometimes people just ran their hands along the exterior surfaces or stopped for a photo or selfie.
Some highlights of interaction during the 2015 Market Street Prototyping Festival in San Francisco included a band of CrossFit athletes putting Active Rest through its paces with lots of climbing and acrobatics, a band set up in front and made Active Rest its backdrop for an afternoon show, and even a nun was photographed reaching up to grab hold of the strata in her full habit one evening.
Step 8: Thank You!
We owe a great deal to the Market Street Prototyping Festival, the staff and student volunteers at the Academy of Art University's Architecture program, and the many donors who gave to our Indiegogo campaign to fund Active Rest.
Those who donated had their names engraved on the base layers of Active Rest, so that anyone peering or climbing inside could see who helped make this installation a reality.
Thank you as well for checking out this instructable. We look forward to further developing Active Rest into a durable, longterm installation that can be rapidly deployed to activate our urban streetscapes. If you decide to create a similar kind of urban-activating installation, please let us know by e-mailing using the addresses shown in the image above.
In the meantime, stay tuned for more from the WoodShed Collaborative!
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