Author, Publisher, Developer, Stitchcoder


And Now for Something Completely Different: Transparently Obvious Models

After a decade of writing books only about chemistry, I have started on something completely new. I call them Mechanical GIFs, because they are a lot like animated GIFs, but they are real mechanical devices that you can hold in your hand—and that I will sell you kits of at my new website,

The name is also a play on the r/mechanical_gifs subreddit, which contains many actual animated GIFs of interesting mechanical devices. (Of course the animated images you see here are actual GIFs, but they are GIFs assembled from photographs of a real object doing exactly what it looks like it's doing. There is no CGI or Photoshop involved here.)

My original motivation for making these models was that I had started working on a new book, tentatively called Things, which will require a lot of illustrations of how various kinds of mechanisms work. (It's a sort of "Way Things Work" book done by someone—me—who is really in love with mechanical devices.) In the past my books have always been filled with real photographs of real things, and I wanted to keep it that way as much as possible.

The problem with real mechanisms is that most of them are completely opaque, both literally and figuratively. They are typically made of metal, wood, or opaque plastic. And they are very complicated because they are meant to be practical, and practical always means a bunch of distracting realities have to be taken into account.

What I wanted was real things I could photograph but which would be as easy to understand as a schematic drawing. So I decided that I would make simplified, abstracted, stylized versions of the mechanisms I was writing about, and take pictures of them. 

I spent some time thinking about how best to go about making these things. I knew they would have intricate, difficult-to-make shapes, so conventional hand craft methods would be tedious. The three obvious choices were 3D printing, CNC machining, and laser cutting.


3D printing is immediately disqualified because a fundamental requirement for the designs is that they be transparent. Not just translucent, but optically clear like glass, so the inner workings are totally visible. You can't 3D print fully transparent parts (well, you sort of can using the incredibly expensive and slow resin curing method, but even those parts require tedious post-processing and are never really glass-smooth). Also 3D printed parts just always look ugly, sorry.


CNC machining is disqualified because it too does not leave a glass-smooth surface, and it has limitations when making small, delicate parts out of glass-clear plastics (because the plastic is brittle, and the machine is whacking it very hard).

So that leaves laser cutting as the tool of choice. The big disadvantage of laser cutters is that they can fundamentally only make flat things. You start with a flat sheet of acrylic and you end up with another flat sheet of acrylic that has a different outline. Fortunately it turns out that this limitation is a desirable creative constraint.

A big reason real devices are hard to understand is that they typically fold their action into complex three-dimensional shapes. Moving parts are going in all directions, overlapping, going through each other, and so on. In a laser-cut re-imagining of the same mechanism, everything needs to be flattened out. The different parts of the machine need to be separated into geographically distinct regions, all in the same plane rather than stacked up in the third dimension.

Good examples of what I mean by "stylized" and "separated into different regions" can be seen in this thing, which I call a Right-Angle Steam Engine

It represents an engine with a double-acting piston (it both pushes and pulls), and a spool valve (looks like a spool of thread). The job of the valve is to direct steam first to one side and then the other side of the piston, at the correct times to keep the engine spinning. (You can read more about the details of how this works on my page describing this model.) The point I'm making here is that this design completely "deconstructs" the working parts of the engine. The valve and piston are far apart (normally they would be right on top of each other to keep the steam path as short as possible). The connecting rods that link the crank arm on the flywheel to the piston and valve are as simple as they possibly can be. And the right-angle orientation between the piston and valve make explicit that the motions of these two parts are harmonic (follow a sine wave), and ninety degrees out of phase with each other.

I have several other designs of steam engine that move progressively closer to how real ones are laid out, but still retain the flattened, separated aesthetic.

The last one is actually operating on two layers (notice how the green and amber parts are on top of each other. This make it the most like a real engine, which would have a crank shaft with two out-of-phase crank arms. But the multiple layers also makes it the least easy to understand: It is best appreciated after studying the other two.

Steam engines are all about timing. You can't get an intuitive feel for them by looking at static images. And you can't (or at least I can't)  really "get" them by looking at animations. They are either going too fast, so you don't see how the valve and piston motions relate, or they are going too slow, so the dynamic nature of the interplay of movements is not clear. What you need is something you can move backwards and forwards at will, interactively. What you need is a physical model. 

Perhaps the best example of what I mean by the tagline Transparently Obvious is this model of a pin-tumbler lock. You can plainly and obviously see that there are a series of pins of different lengths which are blocking the movement of a sliding plate (which needs to move in order to release the catch). When the key is inserted, the different levels on the key are exactly right to align the tops of all the pins, allowing the plate to slide. This is exactly how all pin-tumbler locks work. (Except that they typically rotate into the third dimension rather than sliding, though there are a few that slide exactly like this one). 

Actually, it's not 100% obvious from the animation you see here. To be completely obvious, you have to have the physical model in your hand. Then you can feel the sliding plate, feel how the pins are blocking it, feel how the resistance of the key to being inserted goes up and down as it encounters more and more pins (which you will then start recognizing with real locks, allowing you to guess at the relative lengths of the pins without seeing any of them, just from the feel of the key).

So, deep breath....I am actually manufacturing and proposing to sell these models. I have a couple dozen designs worked out, of which I have chosen six to release for what amounts to initial test-marketing. For those I have retail packaging, efficient layouts for mass production, and a stock of parts.

I have no idea if people are going to like these things. I mean, I think they are very cool and fun to hold and play with. They really do what you see here (and in the more conventional videos on Even my kids seem to like them, and they automatically think everything I do is boring.

I have the laser cutter, I have the plastic, screws, packaging, and the hundred other things needed to semi-mass produce the models. You, as my faithful Blog/Facebook readers, are getting a sneak peak at the website: I haven't announced it anywhere else and don't plan to until next week. As I said, I have no idea if these will be popular or not. If they are, I can make probably a few hundred up to maybe a thousand in time for x-mas (it's a fast and powerful laser cutter). If they are not popular, well, I think they'll find a market in museum gift shops, and if nothing else I needed to design them for my book anyway.... 

Since you're going to be the first people looking at the website (I hope?), I would much appreciate any comments you have, like typos, broken links, this is stupid, go back to making Apps, or whatever comes to mind. Leave comments on this post or email me.

Theodore Gray6 Comments