Types of 3D printers
There are two main categories of 3D printers for home users: FDM and SLA. Those acronyms might not tell you anything, and their expansions are probably just as arcane. FDM stands for fused deposition manufacturing and SLA is stereolithography. (Why is it not just SL? I don’t know.) But don’t worry about “deposition” and “lithography” just know that an FMD printer melts a rod of plastic and extrudes it as a fine stream into a pattern or shape and an SLA printer projects an image onto a light-setting resin to make it set into a shape. Both types make a 3D object one thin layer atop another.
SLA printers offer high resolution and so can make highly detailed prints. They are the printer of choice for people who make miniature figurines, for example, where the high resolution enables the production of wonderfully detailed objects. See here for examples. Usually SLA printers can only make relatively small objects, but fountain pens are made of small objects and so that limitation is not important. What’s more important is the types of plastic that can be printed by SLA.
SLA printers have to use photopolymerising resins which are basically liquid acrylics or epoxies (and maybe others too—I’m not an expert on SLA). I may be asking for trouble here, but judging from a DuckDuckGo image search, the number of different resin types and colours is tiny compared to the range of plastic types and colours for FDM printers. And for my purposes, the limited palette of plastics of SLA printers is a problem and so I use an FDM printer.
The level of detail possible with an FDM printer depends on the quality of the printer, the size of the nozzle through which the plastic is extruded, and the properties of the molten plastic. Happily, a good printer has a high enough resolution to make a lovely fountain pen out of PLA (poly-lactic acid), the plastic that is the easiest of all to print. And equally happily, there are more colours and styles of PLA than there are of any other 3D printing filament! One of the companies that I buy from offers 25 different brands or types of PLA filament, and each of them comes in many colours. Yummy!
PLA is made from plant-derived starch and so it’s a ‘bio-plastic’ and is, allegedly, compostable and biodegradable. In practice PLA does not break down even after years of exposure outside. The compostability refers to high temperature industrial composting and so there is probably no environmental benefit to the PLA beyond it being made from plant-derived starch rather than fossil oil.
3D printing rockets and houses
Yep, rockets. Space rockets.
There are three important types of 3D printers that I have not yet mentioned, powdered bed fusion, wire welding, and concrete extrusion.
Powdered bed printers work by fusing together a layer of fine powder which is then covered by another fine layer of powder to be fused, and so on. How the powder is fused depends on the nature of the powder. Some home experimenters made 3D printers that fused baking powder or talcum powder with super glue fired out of an inkjet printer nozzle, but industrial powdered bed printers can use metal powders and they are fused (sintered) by heating with high power lasers. 3D printing can make parts that have shaped and voids that would be difficult or even impossible to form using conventional machining from chunks of metal, and so 3D printing has great potential for aerospace components such as jet engine parts. In fact, you might already have flown in a plane powered by engines with 3D printed parts.
Rocket parts have been made with powdered bed fusion printers, but at least one company is making rockets virtually ENTIRELY with 3D printers. They are using a welding-like 3D printing method that fuses metallic wire in a manner quite similar to the way that FDM printers fuse plastic filaments.
Even though those uses of 3D printing might sound exciting, the most important use of 3D printing is the production of fountain pens!