Introduction: Mantis - the $20 Floating Leverage Table

Picture of 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

Picture of 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

Picture of 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
  • welder
  • 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

Picture of 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

Picture of 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.

Comments

nil123-3 (author)2017-09-09

it's really nice.

kcode-mcneil (author)2017-01-09

I love the design and am going to try it out. Thank you for sharing.

Do you think it would be stable enough for a TV stand I was thinking I might counter sink the support arm under the thumb in a 3 inch natural oak slab, I have been drying for 10 years waiting for the perfect project.

3 inch solid oak sounds pretty heavy. I made my top look heavy by using the skirts around the sides, but tried to keep it as light as possible. My example will hold a tv, although it does flex a bit. The counter sink idea sounds interesting to hide the support and will also stabilize it. The down side is that you wouldn't be able to re-position the legs if you wanted to.
Some other commenters have suggested alternative materials that could beef it up, like black 1" water pipe (imrobber). It's a cheap enough project that you can experiment. Thanks for the feedback.

expatrick3 (author)2017-01-08

Great Design! I think if you want to win a contest try this. Give specific measurements for the table you created,then give the dimensions you used for your table. Example legs are 32inches from ground to table top, Thumb is 4 inches long and forefinger is 6inches long, the space between is 2inches, the table top is "x" inches thick...you have a winning idea...just be as specific as possible...thanks

planesdesign (author)expatrick32017-01-09

Thanks for the tip. This was my first instructable and I wasn't sure how detailed I should get. Since the system really is about the supports, I left the details about my specific top a little vague.

Mjtrinihobby (author)2017-01-09

Voted.

imrobber (author)2017-01-08

Great idea and I like the inexpensiveness. Like others, I don't have access to a welder but I imagine you could use black (1" water) pipe with T's and elbows to accomplish much the same. Would be more expensive but can't think of a reason why it wouldn't work. In addition might be more substantial and less flexible. Thanks for sharing!

planesdesign (author)imrobber2017-01-08

Sounds like a feasible option to me. That might even make the spacing between the supports more adjustable. I was going for a clean-industrial look, but the pipe may give it a cool steampunk vibe... and would probably make it more rigid as well.

peterjens (author)2017-01-08

Brilliant design. Woe to me for not having a welder friend. I bet any welder would love to take on this project and I would love to pay them just to have a table like this. I also like the pattern of your table top. I hope you win the contest.

planesdesign (author)peterjens2017-01-08

Thanks so much.
Unfortunately, I didn't make the finals of the table contest, but we'll see about the others I entered.

The cutting and welding required for this is minimal and should be only about 20 min work for even the most inexperienced welder. Maybe a makerspace interest group or local community college could help you out.

charlessenf-gm (author)peterjens2017-01-08

I would think the welding could be eliminated by using two long carriage bolts as the pinschers. The legs could be fabricated out of hardwood with the 'feet' planed into a semi-circle where they touched the floor.

As well, the pinschers could be fitted into the shelf and effectively hidden within an 'apron' or void at the rear of the shelf such that the mechanics were 'inside' the rear of the shelf.

"Hiding' the upper parts withing the shelf would also allow for longer 'pinschers' and even greated support/stability.

XTL (author)2017-01-08

Great design. Very impressive and clean..
You might consider adding a thin strip of hardwood, inlayed into the top - under the metal bar - which would help to spread the load and prevent indentation if the primary wood is a softwood. Also a nice visual 'feature'.

psalinas vergne (author)2017-01-08

Me agrado, y ahora entiendo lo que vi cuando era adolescente en una casa de una de las amistades de mis padres, creí que era una especie de asador o forma de atizador. Pero tu presentación me aclaro la confusión. Gracias.

deathbyproxy (author)2016-12-27

The simplicity and practically is so convenient. I look forward to trying this once I get to grips with my new Mig,no gas Welder.

Is there any issue with stability if the top is not heavy enough?

If the top is constructed as a Torsion Box, its weight relative to its strength is lessened considerably.

The placement of the inside supports f a torsion box could be such that they 'captured' the 'pinscher' bits - which could, then, be made almost as long as the shelf is deep.

jproffer (author)deathbyproxy2016-12-28

the amount of weight the top can support really depends on the strength of the wood at the leverage points. There's a massive amount of force on them that goes up as the weight gets further away. So be sure to use hard woods.

I don't think the weight of the top will affect the stability as much as the rigidity and angle of the legs. When building the prototype, I used a 2x4 as a top.

CraftAndu (author)2017-01-02

The philosophy in the begining is funny. Great project. Voted

planesdesign (author)CraftAndu2017-01-02

Thanks!

DanL63 (author)2016-12-27

simpler is always better. nice concept!

rafununu (author)2016-12-27

Clever, I would have found this myself.

ksjunto (author)2016-12-27

Very cool table!

Swansong (author)2016-12-26

This is gorgeous!

planesdesign (author)Swansong2016-12-27

Thanks.

chienline (author)2016-12-26

This is cool. And portable. I am thinking of using a thicker tabletop and/or reducing the distance between the thumb and support arm. Drill two holes on the tabletop side to slide in (hide) the thumbs so that we get a clean flat table top and exact distribution distance of the legs every time we move it. Thanks for sharing this idea ^^

planesdesign (author)chienline2016-12-27

Sounds like a cool mod. I would like to see how it turns out.

rstupplebeen (author)2016-12-27

I love the look and concept. Do you think it could work as a desk or would it bounce?

The prototype I built does flex, but I think a few small tweaks would really help stiffen it up. Originally, I was going to use square stock for the vertical support for that reason. A small diagonal support at the support arm and foot would also help. Good luck and let me know how it goes.

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