Introduction to 3D Printing

"The coolest toys don’t have to be bought; they can be built. In fact, sometimes the only way they’ll ever exist is if you make them yourself."

This is one of my all-time favorite quotes from the legendary maker, Adam Savage. Although I didn’t know it at the time, this quote perfectly epitomizes my childhood, nerding out on building RC model aircraft with my dad. Building a functional model airplane from a pile of balsa wood was the most rewarding experience to us, and we built and flew dozens of airplanes throughout a 10-plus-year span. Those experiences with my dad are a huge reason why I love solving problems as a design engineer today. Those experiences as a kid, paired with the engineering design and prototyping skills I’ve built as an engineer, have led me to a whole new world of crafting model aircraft parts: the world of 3D printing. 3D printing technology has been around at an industrial level since the mid-1980s, but desktop 3D printing technology has become more mainstream within the last decade. Also known as rapid prototyping, additive manufacturing, or digital fabrication, this exciting technology has become more accessible during the last five years. The 3D printing community has grown incredibly fast, with millions of consumer-level printers sold worldwide, but one of the most exciting recent developments is that the 3D printing and model aviation communities are starting to merge. Thousands of model aviators have started to notice how powerful a 3D printer can be as part of their toolboxes. Additionally, I see 3D printing as an avenue to attract new pilots to our hobby, giving the next generation of builders the ability to inexpensively fabricate unique, custom parts, or even entire airframes, on a desktop machine. For those model aviators who have been timid to take the plunge into the world of 3D printing, let’s go through a broad overview of the technology, some of the potential applications within model aviation, and available resources for individuals who are interested in learning more. 3D printing is a broad term that covers 10 or more types of technologies, each of which has its own pros and cons. Although I will focus on the two most common types of consumer-level 3D printers, they all function using the same underlying process. A digital model is turned into a tangible, solid, 3D object by laying down successive, thin layers of material. The basic workflow for operating a 3D printer is pretty simple. A computer 3D model is either downloaded, 3D scanned, or created in a Computer-Aided Design (CAD) program. The typical file type used for 3D printing is called a Stereolithography (STL) file. The STL file is prepared for printing in a specialized 3D printing software (there are several free or paid software programs available) by breaking the model into many thin, horizontal layers using a process called slicing. The software exports the sliced model as G-code, which is loaded onto the 3D printer through a USB cable, a flash drive, or over Wi-Fi. The 3D printer reads every slice of the model and prints it layer by layer. Imagine it this way: The user creates or downloads a digital 3D model of a whole loaf of bread on his or her computer, the 3D printing software digitally slices the bread into slices of equal thickness, and the 3D printer stacks each slice to create a whole loaf in the real world. (I don’t recommend eating 3D printed parts. They will be too crunchy, tasteless, and extremely hazardous to your health.) The two most common consumer-level 3D printing technologies are Fused-Deposition Modeling (FDM) and Stereolithography Apparatus (SLA). SLA was the world’s first 3D printing technology, developed in the mid-1980s. During the SLA printing process, a high-accuracy laser hardens a liquid, photo-curable resin, layer by layer, to create a solid, 3D object. Because the spot size of the laser is so fine, SLA parts are typically extremely accurate, smooth, and maintain an incredible level of detail. ] The SLA material options are slightly more limited than those with FDM printers. Materials ranging from standard resins to strong, engineering-grade resins are available; however, even parts built with engineering-grade resins can be a bit more fragile than real thermoplastic parts built using an FDM printer. As far as RC modeling applications go, SLA prints are ideal for detail parts that will not undergo much wear and tear. Scale details such as custom cockpits, pilot figures, and military ordnance are excellent applications for SLA. SLA excels at printing small parts as well, such as air scoops, exhaust ports, or pitot tubes. Although the cost to own and operate an SLA machine is typically higher, the beauty of a part produced with this technology is unmatched by other technologies.

SLA pros:

• Creates highly detailed, smooth-surface models.
• Parts take spray paints, brush paints, and airbrushed paint well.

SLA cons:

• Machine, material, and consumable costs are more expensive.
• Post-processing of parts is more involved. Parts need to be rinsed in an alcohol bath and post-cured in UV light before handling.
• The maximum build size is typically smaller than FDM.

FDM printers typically come to mind when discussing desktop 3D printers. They are the most common and accessible consumer-level 3D printers available. During the FDM printing process, a thermoplastic filament is heated to its melting point through a small-diameter nozzle and extruded onto the print bed, layer by layer. It is essentially a hot glue gun on a gantry. Although parts printed with an FDM machine are not as smooth as SLA parts, they are typically quite strong. Plus, the material options for FDM printers are vast and less expensive. Materials range from entry-level polylactic acid (PLA), which is an earth-friendly, printer-friendly, rigid plastic, to engineering-grade materials such as acrylonitrile butadiene styrene (ABS), polycarbonate, and several glassfilled or carbon-fiber-filled varieties. It is even possible to print highly flexible, rubber-like parts with thermoplastic polyurethane (TPU) or thermoplastic elastomer (TPE). Here are some available resources that can help you on your exciting journey into the world of 3D printing! DOWNLOADABLE 3D PRINTABLE FILES: Thingiverse: www.thingiverse.com Cults: www.cults3d.com 3DAeroventures: www.3daeroventures.com 3DLabPrint: www.3dlabprint.com DagsDesigns: www.atwoodaviation.net 3D-PRINTED RC ACCESSORIES FOR PURCHASE: RC Geeks: www.rcgeeks.co.uk IFlyTailies.com: www.iflytailies.com Motion RC: www.motionrc.com THE MOST ROBUST, FREE 3D CAD PROGRAM AVAILABLE: Autodesk Fusion 360 www.autodesk.com/products/fusion-360/overview 3D-PRINTING SLICER PROGRAMS: Simplify3D: www.simplify3d.com Ultimaker: www.ultimaker.com/software/ultimaker-cura Prusa3D: www.prusa3d.com/prusaslicer RECOMMENDED FDM PRINTERS: Creality Ender 3 Pro: www.creality3dofficial.com/products/creality-ender-3-pro-3d-printer Prusa MK3S: www.prusa3d.com RECOMMENDED SLA PRINTER: Formlabs Form 3: https://formlabs.com/3d-printers/form-3 Potential RC modeling applications with FDM parts are vast as well. FDM printers are typically outfitted with a larger print bed than SLA printers, and parts can be printed with a hollow, honeycombed internal structure. Thus, larger, lightweight scale details, such as replica radial engines, wheel fairings, larger ordnance, or drop tanks, are possible. Functional parts, such as scale tires, tail wheel assemblies, electric motor mounts, spinners, or even entire airframes, have been proven to work.

FDM pros:

• The parts are robust and lightweight.
• The machine and material costs are low.
• The maximum build size is larger than with SLA.
• Material options are vast.
• Parts can be sanded, primed, and painted.

FDM cons:

• The parts have a rougher surface texture than with SLA.
• The achievable level of detail is slightly less than with SLA.

No matter which technology you go with, the 3D printing community in general is large, so getting help from fellow enthusiasts is not difficult. Downloadable 3D designs—either free or paid—are readily available, excellent resources to get you started in 3D printing; however, to unlock a 3D printer’s full potential, learning basic 3D CAD skills is ideal. Check out the links in the sidebar to learn more about downloadable designs and some entry-level 3D CAD programs. It is understandable to be timid about diving into a new technology—especially a technology that has a high learning curve. The one thing I hear the most often from those who are new to the 3D printing world is that they didn’t understand the possibilities with 3D printing until they had constant access to a printer. My personal development with FDM printers in RC has gone from designing a simple foam glider motor pod with my son to designing and printing entire airframes with exciting success. Yes, it takes time to learn, but when you get those creative 3D juices flowing, the possibilities are truly endless. I guess you could say 3D printing really is the best thing since sliced bread.