I've been using an XYZ Printing Da Vinci 2.0 Duo, which has had obstacles but overall held its value for over a year of regular usage. I'm thankful Dennis introduced me to the brand. The proprietary filament has been predictably limiting, but the build volume has been great. I also planned to use the Duo to help build a more specific printing setup once I've better understood what Touchdown Delivery needs long-term. This material reevaluation has been needed, and I'm looking forward to creating some illustrative images for V8 showing where the plastics below will be incorporated.
From Most Attractive to Least Useful:
- Polycarbonate Blends - Desirable because of its strength, and UV stable for long enough to fulfill the planned lifetime of the drone. The best choice for structural prints. PC Max Is the popular brand, but it’s relatively expensive, so I’d like to test a single roll first.
- PET/PETG - This is such a common plastic, it’s recyclable in most cities as beverage containers and other packaging. It can also print clear with Glycol-modified additives (the G in PETG) and has an average glass transition temperature at 82 C (180 F). Although PLA has a 1.57% density advantage, the higher structurally operational temperature range of PETG makes it the better choice for the flight prints.
- ASA - Slightly more flexible than ABS, just as inexpensive, and most importantly UV resistant, ASA is a choice material for several exterior prints. It's polystyrene based, very common in many appliances, and easy to transition from printed prototypes to injection molded products. It's great for grips and landing feet. ASA can be printed on most ABS-capable set ups. Color options aren’t great, but the longevity is comparatively more important for many exterior components, such as the servo mounting and handles. It also can be smoothed with acetone.
- Flexible Options (TPU) - These are specialized Urethanes. The key consideration in choosing which filament is whether the component in question requires flexibility or flexibility and elasticity. For small and mid sized components where softness is desired, (weather sealing, fabric backing, vibration isolating) printing in a low-A rating filament is reliable if the settings are right. I haven’t seen any ultra soft and opaque/clear options. For harder prints (higher A rating) where tendon-like or high usage properties are required, there are generally even more options, even with opaque colors. Some brands I’d like to try are Polyflex by Polymaker, Essentium’s 90A, Makeshaper 85A, Fiberlogy Fiberflex, and Diabase X60 60A.
- Wood/Metallic/and Textured - These require some tuning for the individual print, and typically use PLA as the base plastic. Hatchbox, Proto Pasta Rustable Iron, Azure Film, are some common brands I’d like to try, particularly the H2O2 reactive rusting, Pine, cork, and bamboo filaments. I’d like to apply these materials to a few interior clasps. Multi-material printing using compatible plastics can allow a clasp to be printed with a structural aspect and a exterior shell aspect using something less structural, like cork. For the first flock of drones, some will have a rubberized neoprene foam interior and some will have a cotton-backed fabric interior. The clamping is the same regardless of the material. Having the capability to print in wooden and metallic textures gives a lot of design possibility for Partners to influence their customers’ delivery experience.
- ABS - I love ABS for the color range the ubiquity provides and the resolution smoothing possibilities it allows with acetone. This can be by brush or vapor. It’s considerably less dense than PLA as well, at around 7.8% difference. Great for early prototyping, but shrinkage makes it so the final prototypes won't be ABS.
- PLA - It has a low thermal threshold which is limiting for structural applications considering what landing on asphalt on a hot day will be like. However, the options for opacity and it is ubiquitous in the 3D printing population make it a great option for prototyping. It has an average glass transition temperature at 63 C (145 F).
A product like a drone will benefit immensely in the near future from being largely designed for print. This is because the printing will become increasingly less labor intensive as well as higher resolution. In addition, it allows for entirely local production, which not only eliminates pre-production transport costs and some taxes, but is more ethical in that it prevents the need to contract with companies which might have associated labor that is unscrupulous.
Additionally, by eventually investing in the needed machinery for rectification, Touchdown Delivery can use recovered support material and old parts to supplement on-site production from beads or welding-rod style stock. While I am still playing with the options for specific machines in my Production Budget, I continue to feel optimistic about printing being a major fabrication mode in the first flock of drones.