The Marlin Principle

Around 2011 I got bored with web development and decided to find a new direction, expand on my programming skills, and learn about electronics and robotics, with no particular destination in mind.

At that time a lot of things were happening. The “maker” and “right to repair” movements were gaining momentum. A new generation of inexpensive single-board computers and micro-controllers had begun to make their appearance. Sites like AdaFruit were beginning to gain popularity. It seemed like an opportune time for an experienced creative software engineer to jump into the fray and find out what all this transistor logic was all about.

When I went looking for a good starter project I was thinking I might build an FM radio or an LED pixel display (and I may yet). But as soon as I started my search something special caught my attention. There was a machine called a RepRap (shorthand for Replicating Rapid Prototyper) that could print 3D objects out of plastic, and you could build it yourself from a collection of inexpensive electronic components and other secondhand parts.

RepRap was born out of an ambitious open source project with the aim to build a machine that can create all of the parts needed to replicate itself – and it needed our help to evolve.

Seeing a RepRap for the first time was a revelation, not unlike that fateful day in 1978 when I saw BASIC for the first time (on a TRS-80) and sensed the far-reaching implications of being able to make your own software. Imagine, if you will, now being able to create any object that you could model, generate, imagine, or describe. At least, in plastic.

By the time I discovered this exciting project it had been going on for nearly 6 years. But it turns out that my timing was auspicious. Many of the early problems had been solved, new printer designs and high-quality machined and injection-molded parts were beginning to appear. No longer (for better or worse, in my case) did you need to solder your own board from components – although the option still exists.

At this time, thanks to companies like Makerbot and 3D Systems, these machines we now call “3D printers” have hit the mainstream. In fact, they are in danger of becoming all-too-common under-utilised relics, sitting disused in schools, homes, and workplaces, just at the time when STE(A)M is gaining momentum.

The Machine Principle

While 3D printers come a long way from their humble beginnings in Adrian Bowyers’ lab, today’s machines still follow the same simple principles and use almost all of the same components. The main components that make a 3D printer possible are:

- **Heaters and Nozzles**: To melt plastic filament you need a good source of heat. A big resistor (an electronic component that converts current into heat) does the job. There are many nozzle designs, but the essential part is a heater that can maintain a consistent temperature.
- **Electronic Stepper Motors**: These weighty black and gray metal cubes literally do all the heavy lifting. Inside, powerful electromagnets hold a metal "stator" precisely in one of 3200 positions. These magnets need to be powerful enough to move the X, Y, and Z axes.
- **Belts, Pulleys, Bearings, Rods**: There are a lot of ways to move a nozzle around.