I finally got a 3D printer. Well, technically Lara got me a 3D printer, but I’ve been waffling about it for so long that it’s really on me. Anyways, it’s here now. And it’s super cool.

Having printed a grand lifetime total of ten models, I could not be more of a novice. But as I was trial-and-erroring my way through my first project, I did learn some useful stuff — strikingly, stuff with interesting parallels to leadership and parenting. But while I thought these lessons would be fun to share, they also feel just a bit “on the nose,” so I’m going to spare you the soapbox. Let’s just nerd out over some 3D printing stuff, and if you happen to make the same connections I did, well, that’d be cool too.

The very basic basics

Just to get ourselves oriented here, my printer is a Prusa i3 MKS+, and it’s pretty awesome. It seems like you can 3D print anything these days (how about food, or these no-seam sweaters from Oliver Charles that I love) — but the OG technology uses spools of plastic filament as the construction material. The filament is melted and laid down in layers starting from the bottom of the piece building upwards. Just as with regular printers, you can dial the “resolution” up or down, creating more detailed models at the expense of speed.

Creation here involves three steps:

1. Model design using a CAD program to describe a three-dimensional shape, typically saved in an STL file. High-end CAD tools have been around forever, but the popularity of 3D printing has spawned a bunch of simpler alternatives. I haven’t even really begun to get good at this, so I’m starting with Tinkercad, a beginner-focused online tool created by the folks at Autodesk. If you’re not into creating models yourself, there are gazillions available to download at places like Printables.
2. Slicing the design into a set of bottom-to-top horizontal layers that can be laid down sequentially to build the model. I’ve been using Ultimaker Cura to do this, and as we’ll see, it’s way more complicated than it first appears. Sliced models are generally stored in G-Code, a programming language interpreted by 3D printers.
3. Printing the design on an actual printer. Which seems pretty self-explanatory.

Introducing Malcolm

As soon as she heard I’d gotten a printer, my D&D-loving daughter sent me an STL file for one of her characters. Malcolm (a magical half-dragon book nerd it appears) was created at Hero Forge, a neat site that lets gamers turn their paper-based characters into 3D models. Malcolm stands about an inch and a half high and is quite detailed.

I’m pretty bad at reading directions, so I basically googled “STL to GCODE”, downloaded Cura, hit the “Slice” button, saved the file to an SD card and started it printing. Which, I have to say, actually looked promising at first. But about a third of the way in, the model popped off the build plate and fell over. Of course the printer had no way of knowing this had happened, so it kept trying to lay down filament layers in midair. This did not end well and required quite a bit of cleanup.

Thus began my quest to print a quality Malcolm.

Support at the beginning

It turns out that this “popping off” problem is pretty common and is referred to as “build plate adhesion.” As each layer is applied, it applies a bit of lateral drag to the layer(s) below. The layers themselves bond pretty securely — which obviously has to be the case, or else the build wouldn’t hold together. But at the bottom, the attachment between the model and plate is pretty weak — which it also has to be, or else you couldn’t remove the build from the printer when it was finished!

This balance is the central challenge to successful printing — temporary support bonds need to be strong enough to do their jobs during the print, but weak enough to detach cleanly at the end.

There are tons of different ways that folks address this: build plate material, obsessive cleaning, even putting down a layer of glue stick before printing. But what seems to be the most effective is to print a “brim” around the model itself. A “brim” is a very thin layer that spreads around the base of the model like a shallow puddle, creating (a) more surface area to adhere to the plate, and (b) more resistance to lateral force as the layers stack up. The brim just peels off when the print is finished, so the only real cost is a bit of print time and extra filament.

The lesson: a solid base sets things up for success.

Support along the way

The next problem was Malcolm’s book and tail — or rather, the empty space underneath them. Remember that models build bottom-up, each layer sitting atop the one below. But what happens when there isn’t a layer below? Obviously the filament can’t just float in mid-air. (Well ok, obvious after I just let fate take the wheel that first time. Whoops.)

Completely empty space below the model is an extreme case of “overhang” — surfaces that rise up at an outward angle. Because the filament is really sticky, you actually can get away with a bit of this. It depends on the printer and material, but generally up to about fifty degrees of slope is OK. Beyond this, successful prints require some kind of support structure underneath the model. And wow are there a ton of ways to approach it. This kind of hyper-configurability can be tough to deal with and generally happens when we don’t quite understand the problem enough to handle it well in software. Yeah, been there.

Traditional printing supports are just thin, vertical pillars that extend from the model down until it finds support, either on another part of the model or on the build plate. As long as you can detach these supports from the model when it’s finished, it works pretty well. But sometimes there are little concave sections where the pillars can be tough to remove — or really tall models where the pillars have to be so tall they become unstable. For these latter cases, there’s yet more configuration that enables “support for the supports” at the cost of time and material.

“Tree supports” are a newer alternative to pillars. Instead of purely vertical supports, one or more “trunks” are planted on the build plate, outside of the model proper. “Branches” in all their fractal glory extend from the trunks at “safe” upward angles (i.e., less than fiftyish degrees) and find their way to the parts of the model that need support. The algorithms for generating tree supports are super-complicated and the end products look a little organically creepy. But folks seem to really like them; they use less overall material and require fewer attachment points to the model itself.

As a newbie, I chose the more traditional pillar model for Malcolm. Which worked great, except on the upper part of the model around his chin and underarms. Especially at the small scale of a minifig, supports in these areas were just too muddy and difficult to remove. This also isn’t uncommon, so the software allows you to manually block supports from parts of the model. The lesson: choosing when and how to apply support is complicated and there’s rarely a one-size fits all approach.

Support at the end

The trickiest bits are the spots where support attaches to the model. We’ve been here already — strong enough to bind, but weak enough to remove without scarring. The primary value that drives this balance is Z Distance (and to a lesser extent XY distance), empty space left between the model and the support itself. At first this seems a little counterintuitive. Ater all, we’re adding supports to fill empty space, right? But it turns out that the filament material melts across the gap, so the two surfaces do touch — just barely enough to create adhesion if you do it right. Yet another example of the physical world being way more nuanced than the digital one.

Another setting that impacts this boundary is the Support Roof (and Floor). Settings here tend to widen the touchpoints between the support and model, creating additional stability. This seems to have been created largely for use with water-soluble support filament. My printer only supports one filament per model, but many printers can use more. This enables prints with multiple colors and materials — like for example, special “support” filament that dissolves away after printing! This is super super cool and there may be an upgrade in my future.

In any case, the lesson: it can be hard to know when and how to let go.

One of my favorite ever books is Walkaway by Cory Doctorow. Its basic premise is that scarcity isn’t real (anymore), but our social and economic systems keep pretending that it is, because it supports existing power structures. One of the key plot devices is 3D printing — with a few basic materials, just about anything could be made just-in-time directly at the point of use. I 100% buy this core premise — and expect that in not-too-many years printing will displace shipping for things like dishwasher parts, mounting brackets, toys and the like. Malcolm himself is an early example!

But we ain’t there yet — there’s a ton to learn and it’s all super finicky and it’s not altogether clear when you’re doing it right. Sounds like some other things in my life. ‘Nuff said!