Folding Table

 

I would be staying with my Dad for one week that summer. At this point a tradition of sorts had been established. A pattern had emerged. While I stayed there, we would work on a project together. That was what we did. The summer previous we had repainted and rebuilt my bike and then, together, cycled to Amsterdam. Once I helped put up a roof. What was it to be this time? Dad’s always working on something, always turning over some problem in his head. It’s the world he lives in. Engineering, business, design - he’s always got a problem on the go. So I asked him ‘Look, I’ve been doing all this studying, it’s got to be good for something right? You got any problems I might be able to help with?’. And this is what he told me:

The Problem

My Dad is a carpenter. He’s been a handyman and a physicist and a few things in between but recently the work’s mostly carpentry. When I visited him that summer he was experiencing somewhat of a space problem: His workshop was a shipping container. Now, shipping containers are very practical places to store things, but they are not large. The issue came in the form of some very large sheets of wood. Not because they didn’t fit in the container (, no it was more subtle than that. The big sheets fit just fine - you could slide them in on their long side and they’d happily lean against container wall. What was lacking was anywhere to cut them up. Think about it, if you have a really big sheet of wood that you want to cut parts from, you need a really big surface to lay it out on first. Storage wasn’t the problem, it was usage. A table was needed, and it would have to fold if it was going to fit.

The blueprint: It would fold to stow away when not in use, and had to be portable so that, when required, it could be manoeuvred into an open space in which it could be unfolded.

Of course, if the most obvious approach to building a folding table sufficed, the table would have already been built. No, it wasn’t enough to just have it fold in the middle - a couple of hinges, sides that rise up like the wings of a courting bird - no, the low ceiling in the container didn’t allow that. Somehow the thing had to fold in some fancier way so that the end result came out much shorter.

By some great stroke of luck, I had just recently been playing around with an idea which, so it turned out, held the answer.

Linkages

I think the reason I knew about any of this to begin with was because of strandbeests.

strandbeest

Strandbeests are wind powered kinetic sculptures which resemble enormous alien crabs made of bamboo scaffolding, videos of which regularly go viral. Something about their movement is unsettling. It is both seemingly natural and yet entirely mechanical. They are thoroughly complex and yet their lifelike meandering still seems like it should be impossible for a bundle of sticks, no matter how complex. Yet bundles of sticks they are, and wander about like tent-pole war-of-the-worlds sand-fleas they do.

What intrigued me, more than the strangeness in their being, was the strangeness in their coming into being. It was conceivable to me that they existed, but that some individual was responsible for that complexity, much less so.

I didn’t understand how the design of such a mechanism was possible. Let’s say you wanted to draw it out, well how? Take a much easier example: a door. To draw a door (on a floorplan or a blueprint), you draw the arc of a circle, indicating the motion that the door makes as it swings. If you tried to draw the motion of these legs in the same way, the picture wouldn’t look like a floorplan or a blueprint - it would look like a Duchamp painting!

Nude descending staircase

No idea how you could design like that.

Okay, so you don’t have to draw it out - you could just make it. You could experiment with the lengths of the limbs and the locations of the hinges in real life rather than on paper. If it doesn’t work, change it. Why worry what a plan of the thing would look like - just keep tweaking till it looks right, right? If you’ve got a hundred years to spare, sure - go ahead. Rather you than me though.

There must be a better way! Clearly I’m building up to saying that there’s a better way. I used a program called Geogebra. It’s not just that though! I have to stress what made this nice wasn’t just that I identified a solution, but how perfectly the solution leveraged my niche area of interest.

I consider myself a connoisseur of graph programs.

geogebra

Quick breakdown: ‘Desmos’ rules the online graph, ‘Geogebra’ rules the world of Greek-style geometric constructions, and mac’s built in ‘Grapher’ wins for convenience and aesthetics of 3D plots. (of course, the more specific your requirements the more likely it is that the graphics package for some programming language will be your only option).

What’s nice is that I bloody love a good graphing program, and it’s not because I have aspirations of doing anything useful with them. I just like drawing graphs! That’s just me, I have to be honest about that.

So to ask my Dad if he had any problems I could help with, and for it to turn out that:

  1. He did.
  2. I could solve the problem with a graphing program (my absolute dream).

Well it was just very fortuitous, that’s what I’m trying to convey.

I should clarify, the reason strandbeests are relevant is because designing legs like those with their many hinges and moving parts, and designing a folding table, are really not so different. It was my curiosity about strandbeests that lead me to learn the name of this type of mechanism: a linkage. Strandbeest legs are linkages, folding tables are linkages. Turns out you can design them all in Geogebra.

The Solution

I think that the process of using geogebra to design linkages is in itself very interesting, and I may create a video presenting that process at some point - for now I will just show you the result of the work.

It went like this: I would mock up some design then show my Dad, and he would feedback on the practicality of it, and how closely it met his design requirements.

By the end of that week I had a complete draft - shown here:

folding table gif

And just for fun, this is what it looks like with all the construction lines shown:

folding table with construction lines

Once the design was agreed on it only took a couple of mornings in the workshop, the purchase of 12 fire-door hinges and years and years of carpentry experience to bring the thing into existence - and here it is for you to behold:

I’m still very proud of the design, and my Dad has been using the table ever since (although he moved his workshop out of the shipping container some time ago so it’s not as necessary as it used to be!). If you’d like to see more of my Dad’s carpentry - check out his instagram.