Introduction: Mantis - the $20 Floating Leverage Table
Our hands don't need screws and brackets in order to hold things firmly... so why should our furniture? The Mantis table uses only leverage and gravity to keep this beautifully simple table top afloat. For about $20 and some marginal wood/metal skills, you can add this functional art to your living space.
Almost 6 years ago, I designed this system after noticing how I was holding a board using my index fingers for support and my thumbs for stability. By tilting my hands inwards, my index fingers stayed in place, but my thumbs applied a downward pressure that "locked" the board in place.
No need for additional hardware, easy to assemble, stores flat... the Mantis is the child of physics and function.
You will need:
- some scrap boards or leftover table top
- inexpensive steel rods (rebar pins)
- access to metal chop saw and welder (friend in my case)
Step 1: About the Mantis "Pincher" Supports
The stars of this show are the supports... or "pinchers".
** WARNING** The nickname comes from their ability to pinch the s*%t out of you hands if you are not careful!
These supports consist of a vertical piece, and 3 horizontal components:
- the "thumb" provides the downward gripping force when the legs are angled in/out
- the support under the table-top
- the foot
You could experiment with different materials, but I used steel due to the substantial forces being applied to the "thumb". I found a very inexpensive and handsome material at my local DIY home store: rebar pins. A 3/4" X 36" solid steel rod is about $5 and comes with a tapered end.
Although the concept is simple, there are a few variables to consider:
- the length of each component
- the spacing between the "thumb" and support arm
- the final resting angle of the legs
Step 2: Fabricating the Supports
You will need to have access to basic metal-working tools. I was lucky enough to have a friend that had the basic tools that I needed:
- metal chop saw
- 90 degree welding magnet
Next, you will want to determine the lengths to cut. A rule of thumb is to cut the feet to be approximately the depth of your table top and the support arms can be a bit shorter. The thumbs only need to be a few inches... just enough to catch the top. The dimensions shown are based on the following table top: 19" x 57" using 7/8" thick boards.
We cut the pieces and butted them at 90 degrees, so no tricky angle cuts were necessary. My friend Matt handled the welding and we were done in no time. Take special care to make sure the two supports have identical measurements. A slight difference in the space between the thumb and support will result is a big final angle difference!
I fudged it for this prototype, but you should be able to use this formula to calculate the required gap between the "thumb" and bottom support.:
Gap = thickness of the top / cos(desired angle) ** make sure your calculator is set to use degrees, not radians **
So, for a 30 degree angle on a 7/8" top, the gap would be: .875" / cos(30deg) = 1.01"
Step 3: The Table Top
All you need is a strong top (nothing that will shatter or deform easily). As long as the table surface is flat on both sides where the supports engage, it really doesn't matter what you use.
** NOTE ** The "thumb" applies a lot of pressure over a small area, so it could dent softer materials, particularly if the angle of the legs is great and/or if additional weight is place on the table.
My table top was made using old barn wood and held together with biscuits. To add to the floating effect, I added skirts to the sides and front to make the top appear thicker and heavier than it was. It also hides the support arm, only exposing the mysterious "thumb" on top.
The Mantis system provides a lot of flexibility in terms of the number of supports to use, which direction to angle them, how closely to space them, etc.
Good luck and I'm looking forward to see how people apply this design to their own creation!
Step 4: Evolution of Mantis
Just a quick addendum to my original post. Thought it may be interesting to some visitors to see how Mantis came about.
The Mantis system evolved over a few iterations of using leverage and gravity to secure a flat surface. The first designs resembled ladders that could support multiple tops. These tops could be reversed to provide different looks.
Although this seemed like a functional concept I wasn't so happy with the bulk and the way the supports took up a large portion of the table top.
So the next version was a slimmed down version that could be re-positioned along the top to give more working space. However, the supports still interfered with the use of the top. I did like how simplicity and overall look were coming together.
That's when the idea of the "thumb" came to me and the ability to minimize the support real estate on the surface while still providing the functionality and design that I was after. In the design mock-up I show how multiple surface can be supported using the same system. I haven't built one of those yet and it would require relatively tight tolerances during fabrication to ensure that there was equal support at all points.