Introduction: PIN WALL
The goal of this project was to design an interactive installation in which the users' actions are recorded, encouraging new users to join the dialogue. The final installation piece in appearance is a circle on a plywood wall composed of wooden "pins" that can be pushed and pulled to hide or reveal light that is emitted from holes in the plywood wall. The project focused heavily on prototyping and fabrication techniques included CNC routing and wood working. The project team consisted of myself (Andrew Cornelis), Maura Chen, Liam Cook, Kevin Meffert, and Kathrine Blackman.
Step 1: Concept Development
Early on in the design process we decided the installation should be some sort of interactive wall; a fixture in the space that would integrate seamlessly with the interior condition of the building. We started by sharing inspiration and precedents of interactive walls with each other.
Through this process we identified the scale and type of interaction we wanted to encourage the user to have. We also identified the components of the design that would facilitate these interactions. There would be some kind of knob that could be pushed and pulled with a corresponding reaction from a light source. These interactions would aggregate to form some sort of density across the wall that would turn these micro actions into larger actions that would be able to be read as a single action.
With these assumptions in mind we dove into prototyping components: the knobs, the wall assembly they connected with, and the lighting fixtures.
Step 2: The Pin
All three components of the installation were designed and prototyped simultaneously, but I will focus on the fabrication of each separately.
The parts of the pin were a wooden head and a steel rod. Initially we scrubbed the internet for wooden knobs that we could order in bulk. We couldn't find any with which we were satisfied with so we decided to fabrication them ourselves.
We choose maple to use for the heads because of its durability and also its color and grain that was the most similar to the ACX plywood (the wood that would be the exposed face of our wall assembly. predetermined by the use of it elsewhere throughout the space where the installation would go).
The fabrication of these first pins used only traditional wood working methods. We first made a large wooden cylinder with a 2" diameter and cut off different thickness disks. Next we drilled a shallow hole into the back of each disk and, using a glue up jig to make sure we were gluing the steel rods into the wooden disks perpendicularly, we fixed the steel rods into the holes on the wooden disks with gorilla glue.
After the glue had set, we inserted the rods of the pins into a drill press, and held various grits of sandpaper against the spinning wood to shape the heads. This was a relatively quick way to get the smoothness we wanted in the pin heads.
We ended up selecting a 3/4" thick wooden head that was rounded with a 1/4" radius on the front and back sides.
Step 3: The Wall Assembly
The components of the wall assembly are the visible 3/4" ACX plywood, a 1/2" sheet of plywood, wooden spacers between the two sheets of plywood, and aluminum tubes embedded in the 1/2" plywood that act as a sheath for the pin steel rods.
The outer sheet of ACX plywood was a given because the interior walls of the space consist of exposed ACX plywood. Our installation would fit in with the other existing walls, aside from the interactive component that we were designing on to it. ACX plywood has one side that has a high quality veneer and a backside that is a rougher cut.
The wooden blocks spacers between the plywood sheets created room for the LED light strips (next step).
The 1/2" sheet of plywood was drilled with holes to hold aluminum tubes that sheathed the steel rods for the pins. We tested various kinds of metal tubing such as brass, steel, and aluminum. Aluminum was the most readily available, the lightest, and the cheapest, so we went with that. The back layer of plywood and embedded tubes needed to be as light as possible while being stable enough to support the tubes and pins that they would hold.
Step 4: The Lighting
The third component of the design was a system of producing light that could fit in the very narrow space of the wall assembly between the two sheets of plywood (about 1.5" of space).
The choice for what kind of lighting fixture to use was simple, LED strips. They are simple to set up, very affordable, and have long life spans.
We adhered the strips to the back of the ACX plywood so that the light was directed at the 1/2" plywood within the wall. At this point we tested different sizes of holes in the the ACX plywood behind each pin head ranging from 1"-2". We were happy with 1-1/2" holes because it let out enough light when in the open condition. Painting the 1/2" plywood sheet white made the light brighter. Finally, painting the backs of the pin heads red allowed us to add variation in color without using different color LEDs.
This step concludes the prototyping portion of the project. In conclusion, the light from the LED strips bounce against the 1/2" plywood, out through the holes cut in the ACX plywood where they hit the backs of the pinheads, and depending on if the pin is in the closed or open position, allow a glowing light to be revealed against the ACX plywood from behind the pin head.
Step 5: Mass Production
At this point we had all of the components of the design figured out and a mock up built with 45 pins. We proceeded to draw up the final design so that we could get a sense of the scale of production, ei how many parts of everything we'd have to make.
The final design was a 4'x4' circle gridded with 860 pins spaced evenly that would centered over two full, 4'x8' sheets of plywood.
The list of materials was as follows:
- 860 steel rods
- 860 wooden pin heads
- 860 aluminum tubes
- 860 nuts (used at the end of each rod as a stopper so you couldn't pull the pin all the way out of the wall)
- 10 LED rolls
- 2 sheets of 3/4" ACX plywood
- 2 sheets of 1/2" plywood
- gorilla glue (for gluing the rods to the pin heads)
- white paint
- red paint
Step 6: Pin Fabrication
The assembly of the pins includes a 1/8" diameter 4" long steel rod, a wooden (maple) pinhead 2" diameter 3/4" thick with 1/4" rounded edges on both sides.
We decided to use a 3-axis CNC router to mill out the pinheads, drill a hole in the center of each for the rod to be placed exactly at the center points, and round the first side of the pinheads. Ideally we would be used the CNC router to round both sides of the pinheads but after consulting out lab manager there was not an apparent way to flip the boards of wood on the CNC router table to accurately round the edges of the other side of the pinheads.
We lined up as many boards of 3/4" maple on the CNC router bed as possible and laid the outlines of the pinheads as close together in the 2d file as we could as to not leave much waste. Maple is a hard wood so we were sure to have multiple passes to not push the drill bits too hard. The total time spent watching the CNC mill out more than 860 of these pinheads was close to 40 hours.
The unrounded sides of the pinheads were rounded using a hand router with a 1/4" round-over bit and a jig. The individual pin heads are secured to slightly raised platforms using Nitto double sided tape. The unlike the roundover bit we used with the CNC router, the bit we used with the hand router has a bearing at the tip that worked with the base of the platform the pinheads were taped on to. This platform acted as a template to just round the edges and not cut past the 1/4" radius. This process was probably the longest of any step.
The steel rods are cut to length and threaded on one end and glued (gorilla glue) into the holes on the pinheads using a glue up jig that makes sure they are perpendicular to the head of the pin. Once the glue has set, we used a drill press to hold and spin the wooden head while we held sandpaper to the pinhead. Using three different grits of ascending fineness, we sanded smooth the pins in their entirety. The pinheads are then finished with 3 coats of clear poly-urethane with sanding in between coats. Lastly, about %50 of the pinheads are painted red on their backsides.
Step 7: Cutting the Holes
The CNC router was crucial in laying out the grid of holes, both in the outer ACX plywood layer and the second 1/2" plywood layer. The 1/2" plywood sheet holds the aluminum tubes that sheath the pins. If the grid alignment of these holes was off at all it would be very apparent. All four sheets of plywood are cut or drilled on the CNC router in a pretty straight forward process.
The 1/2" sheet of plywood is painted white to reflect light better, as well as the back side of the ACX plywood. The frontside of the ACX plywood is finished with clear poly-urethane.
The 1/2" sheets of plywood are mounted to the backsides of the ACX plywood with 1-1/2" wood block spacers.
Lastly the LED strips are adhered and run horizontally between the holes on the backside of the ACX plywood.
Step 8: Final Assembly
The final and most rewarding step was to install all of the aluminum tubes into the 1/2" plywood and sheath and secure the pins in place.
The aluminum tubes are cut to 2" lengths, deburred, pushed halfway into the pre-cut holes on the 1/2" plywood and fixed with glue.
Each pin is pushed through the aluminum tube sheath and a nut is screwed onto the pin rod after it clears the other side of the aluminum tube. The nut acts as a stopper.
Step 9: Reflection
1. Using tool like a CNC router can allow you to be very, very precise, BUT only as precise as you are in measuring your material, mounting it to the CNC bed, and setting up your digital file and tooling paths.
2. When you undertake a project with so many repeated processes in the fabrication, spend the extra time to figure out to work most efficiently! Hand routing the other sides of 860 wooden disks slowed the project down by weeks. We could have spent more time brainstorming an alternative solution.
3. Quality control when selecting material is imperative. We had to toss a lot of maple pinheads because of knots and warping boards that could not be properly secured to the CNC bed.
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