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Bathymetry Coffee Table
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I've been intrigued by furniture design lately, and decided to take a stab at making a custom coffee table based on bathymetry data of the San Francisco bay. Build log is below!
Breaking the Mold - January 2019
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The new plan is to make a silicone mold of the acrylic and then cast a single piece of resin. That way, concrete can be poured around the resin, which will act as a inlay in the final table.
In order to make a mold, the acrylic needed to be exposed for the silicone. Two sides of the MDF box were carefully removed in case re-assembly turned out to be a viable option. |
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Considering the volume of the mold, a brush on silicone was an inexpensive approach as it saved on material cost. I ended up using a SIlicone rubber material called EZ-Brush from "Smooth On". The product is meant to create vacuum bag molds and even a thin layer yields an incredibly strong mold. The material was brushed on in 4 layers.
Once the silicone rubber had cured, a thin layer of Smooth On's Plasti-Paste epoxy was added to created a rigid mother mold.
Working with these products was an absolute treat. I could not be happier with the results and I am sure I'll approach future projects differently knowing complex molds are this accessible.
Test Pour Went Poorly - January 2019
The intricacy of the mold raised concerns about the feasibility of separating the acrylic from the concrete. So I decided to perform a test pour by first creating a small tile with an intricate acrylic inlay. I then masked the MDF board.
As an extra pre-caution, I added a silicon release barrier over the acrylic (aerosol application).
I finished the mold box and poured the concrete.
Once the concrete dried, the mold was broken apart and it was clear that the acrylic could not be separated without destroying the concrete finish.
This was incredibly disappointing, but also somewhat expected. I'm just glad to have verified before pouring the entire table. A different strategy is already in motion :)
Securing the Mold and the Materials - December, 2019
The layers were aligned using pins through the pre-cut alignment holes, and secured together using a tiny bit of super glue. The mold is incredibly secure, but overwhelmingly intricate. This raises concerns around the feasibility of separating the acrylic from the concrete. So a test pour is in order.
Additionally, the materials for the concrete pour were acquired. Moving the bags of concrete made me realize this table is going to be HEAVY!
- Surecrete PreCast x 5
- Additive (5 gallon)
- Sealer
Resizing the Table - December, 2019
After building the frame of the mold, the size of the table just seemed too large (48x42"). I decided to shorten the dimensions a bit (48x36"). Luckily this only took ~5min thanks to the previous work I'd done to parameterize the CAD model. New renders below!
Luckily it was easy to adjust the dimensions. I simply inserted and reinforced a new wall in the existing mold.
Building the Concrete Mold - December, 2019
The next step was building the concrete mold. I started by creating an MDF box.
I created rounded inserts for the curved corners of the table. I used a thin MDF skin and wet the back of the wood to make it more pliable.
The frame of the mold turned out pretty well.
Laser Cut Acrylic - November, 2019
Laser cutting the acrylic went smoothly and the parts look beautiful!
I was sure to add some guide-holes to the templates before laser cutting which should help align the pieces.
Creating Templates for Laser Cutter - November, 2019
Recent travel has kept me from working on the table, but I did manage to create some templates for the laser cutting machine. To save material and cost, I "nested" (efficiently arranged) all the parts to be cut. Jumping between different programs, I was stunned to find poor support and standardization for mechanical drawing formats. A few programs even failed to detect units in a clean .dxf file, and many others preferred SVGs. I would have expected a much cleaner and more efficient workflow for something so common. Nevertheless, I was able to make all parts fit within a half sheet of acrylic, without introducing too many subdivisions. While a more efficient layout could have been achieved, it would mean splitting more pieces and working out a method for align them at mold time. I settled on a nice balance.
While creating the templates I also added some small holes to help align the layered sheets later on.
More CAD - October, 2019
CAD modeling - September, 2019
Generating contour maps from bathymetry data - August, 2019
I want this piece to be engaging, and invite curiosity. And if someone stares into the resin, I'd like their curiosity to be rewarded with actual information about the shape of the bay floor. So rather than freehand this piece, I'll leverage actual scan data. I turned to historic bathymetry data from NOAA.
The first obstacle was generating quantized depth contours that I could import into a CAD program.
I started by writing some software to accomplish the following...
The first obstacle was generating quantized depth contours that I could import into a CAD program.
I started by writing some software to accomplish the following...
- Ingest NOAA data
- Visualize depth maps
- Segment depth maps into clusters and visualize
- Quantize depth maps into discrete sections
I have provided all my source code here: github.com/dcyoung/coffee-table
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My code produces quantized depth maps in the form of colored images. I still needed to convert these to individual binary maps (one for each depth contour) which could be used as templates for CAD. While it wouldn't be difficult to add to the code, I simply used photo editing software to split apart the quantized depth map image and create binary (black & white) maps for each depth. Finally, I exported these binary templates as SVGs (scalable vector graphics), which made the CAD import a lot easier.
Shown below are the produced binary maps for depths 1, 2 and 3.
Shown below are the produced binary maps for depths 1, 2 and 3.
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Initial design - August, 2019
The idea for this table started with a strong desire to experiment with pouring epoxy/resin. Most of the existing resin pour projects I've seen are "river" tables, where resin is poured into a single channel between two pieces of wood. While I find these tables intriguing, I wanted the subject of the pour to be data driven. I decided I'd do a pour outlining the SF bay! Additionally, I started planning around concrete instead of wood, as it should better match my industrial loft.