Introduction: REVOLVE // a Hardware-less Coffee Table
So last year when I had a bit of down time before moving from icy Calgary to sunny-ish San Francisco. I thought I would try my hand at 123D Make and use it to create a piece of furniture that required no hardware for assembly. I wanted to do this for my IKEA challenged friends who never seem to understand that you need to use all the screws they give you, or you have royally screwed up. Inevitably the table/shelf/bed, always comes crashing down on their unsuspecting poor cat. This stupidity has to stop.
So my then roommate and good friend, Paul Hern from Replicate Designs, and I decided to spend a couple days over the cold winter holidays in his beautiful and well heated shop playing on his FROGMill. We spent 2 days from design to finished product.
Step 1: Designing the Basic Form
I wanted the shape of this object to be relatively basic because the slicing process created by the program would be enough of a feature to draw you in. I also needed to have the design done pretty fast because Paul and I only had a couple days to see this project through. I hit the internet for inspiration and came across the Kitaj, a side table by Rodolfo Dordoni.
I wanted to make something a bit bigger and decided to convert this shape into a coffee table. Paul also needed a table for his office (his previous one made by a well known swedish manufacturer may have finally given out because he fell victim to the 'they gave us extra hardware' myth). We landed on the dimensions of 36" x 36" x 22".
In Paul's shop, we happened to come across a circular piece of glass that may have also come from yet another abandoned piece of 'put it together yourself' furniture that found it's inevitable demise. It was around 40" in diameter so we figured we could use this as the top surface of the table if we needed to.
This basic shape is super easy to model in any software platform really, and you can play with the curvature that you like. It's a curve that is spun/revolved around a central axis. I used Rhino to do mine and can't seem to find the file, but I have included my 123D Make (free) file if you would like to make your own. Go for it, you have my blessing.
Step 2: Slicing With 123D Make
Once I brought this shape into 123D Make and fiddled with the options they give you, I was able to land on a slicing technique and angle that I really liked. I also kept an eye out for floating small parts that would break easily. After about an hour or so of playing around, I was satisfied.
The program gives you a spot for you to put in the thickness of your material, which also changes the look of your design. You'll want to take this into account when doing your own version.
Since Paul had plenty of acrylic laying around his studio, we decided that before going big, we would first do up a quick prototype using some acrylic. We scaled the model down by 1/3 until it was 12" in diameter and went with a material thickness of 1/8" since we had more of this in kicking around.
On the right hand side of the screen, 123D Make displays the lines that are used to cut out the shape of each slice in whatever material it is you choose to use. Keep an eye out for little pieces that might break when cutting or moving around and adjust your number of slices and/or angles to find the best outcome you can.
We hit the 'Get Plans' button and save the outlines of the slices. I chose to use an EPS extension since I knew this would easily import into Corel Draw. Unfortunately, 123D Make doesn't do so well at saving cut material by 'nesting' the parts tight into one another. I was able to do this in Corel Draw by hand but this took some time in order to reduce the number of 18"x24" sheets I had to use. Regardless of that, it's all worth it. Not nesting your parts is wasteful and shame on you if you don't do this.
Step 3: The Prototype
Using the nested lines in Corel Draw, we hit print and sent the file to the laser cutter. We made sure not to print slice numbers. Paul has presets for all thicknesses of acrylic so we didn't have to mess around figuring out the best speed and power for the job.
Boom. 2 sheets later, we had all of our parts. Assembly was quick and quite fun but our slot tolerances were too loose. The structure seemed sound, but had we properly measured the thickness of our material, the fit would have been a bit tighter.
Regardless, we were pretty happy with the outcome. We cut an additional circle and laid it on top of the prototype to simulate the glass table top. It's time for the real thing!
Step 4: CNC
Paul and I decided it was time to go big. We made a quick trip to home Depot and decided Version 1 would be done out of chipboard. I quite like the industrial feel of chipboard and it relatively cheap compared to ply. When we got back we made sure to take a set of calipers to the material and measure the thickness. Each sheet was slightly different from each other so we took the average thickness of 0.78" and applied that to the material thickness in the original (unscaled) 123D Make file.
We exported the file again as EPS, but this time I brought it onto ArtCAM which is a CAD/CAM program used to create files for CNC machining. ArtCAM has a pretty awesome nesting function so this didn't take long. We used a 1/4" end mill so that we could make sure all corners had tight radiuses and away we went.
All in all, we had 5 sheets of 4' x 8' chip board to machine. We layed each piece down, loaded the g-code and cut away. for our first sheet we used small tabs to keep the cut parts connected to the stock material but quickly realized that this meant a lot of finishing would be involved.
For the second sheet, we decided to spit the file into 2 separate depths. The first cut was 0.5" deep. Once the entire sheet was done to this thickness, we stopped the CNC and and used 2 short nails on each slice to hold the part down onto the spoiler board. This made sure there was less vibration in the sheet which gave us better cut finishes and also held the part securely during the last pass of the cutter. Pulling off each sheet, we made sure to pul out the nails. since this was chipboard, you could even tell where the left over holes were.
Step 5: Putting It All Together
Assembly was tricky. We started with one of the rotational slices and started adding the angled slices in. When we got about half way through, things became a bit tough. We underestimated the radiuses in each of the inner corners of the slots and realized that the compounded oversite was causing the pieces to not slot in all the way. We began filing the inner corners of the slots and things came together much easier. The last few pieces required some hefty hits with a mallet to get them into place but when it was all done, the whole structure held together really nicely.
Unfortunately we realized that our excitement got the better of us. We should have probably sanded each slice before the assembly stage and weren't willing to disassemble it again due to the feat we had just gone through. So we pulled out the same paper and painstakingly sanded each surface.
To seal the wood and make the color pop, we brushed on a shellac sealer, starting at the top and working our way down. We made sure to get into every little nook and cranny there was and in the end, the piece came alive. The finishing touch was laying the piece of glass on top.
We were done. Now it's time for a name. This is the hardest part of every design for me. I have had many names for this project, but as of today, I am going to call it 'Revolve'. This is an ode to the method used to create the original form that was imported into 123D Make.
Paul and I were pretty happy with our 2 day effort. Paul had a new table and I had a ton of fun making it!