In educating clients and students about 3D printing, before I launch into the technology, the design guidelines and all the amazing stuff people are making, I ask a basic question: Is this something you SHOULD print?
The answer is No for generally two reason: Safety & Method Appropriateness (aka common sense)
First: Safety. There are several ways that 3D printed parts could be used in potentially hazardous ways.
3D printed materials tend to be weaker than their machined or molded counterparts (Yes, there are many amazing efforts out there to change this, but for general purposes, it’s a solid assumption). At the same time, the opportunity to create highly complex, delicate structures is very seductive. If you do not possess the analytical engineering skills to prove your design will hold up under a heavy load, do not 3D print parts whose mechanical failure could result in serious injuries. These include stiletto heels, lawnmower blades, carabiner clips for mountain climbing, or even a new custom cane for your 90 year old aunt.
In addition to mechanical failure, some applications are inappropriate due to the chemical nature of the materials being printed. Many polymerization-based printing methods (methods that harden material using chemical reactions, rather than just melting and cooling a substance) involve the creation of acids and other harmful chemicals as an intermediary step in the resin curing process. Depending on how carefully controlled the process is, some of these chemicals may remain in the final part. These can leach into liquid or food, outgas if heated, or irritate skin and other tissues. For this reason, unless you have a material approved for these applications AND a properly calibrated and maintained printer, skip Dad’s new coffee mug or that custom watch band you were thinking about.
Second: Method Appropriateness
3D printing is an amazing and powerful tool for an innovator to have access too. However, like any tool or fabrication methods, it has its strengths and weaknesses. The risk of using it inefficiently is particularly high among individuals with limited exposure to other fabrication methods. Some years ago, I was swapping stories with another educator who had taught an introductory course in 3D printing. One of her students spent 12 hours and fifty dollars’ worth of material to produce what was, essentially, a box. This could have been purchased for two dollars from the nearest Walmart, or even assembled from foam core and hot glue. One of my own students came to me concerned that the class room 3D printer couldn’t produce the tiny screw threads he needed to assemble his project. I showed him a tap and die set, a box of self-tapping screws, and a tube of plastic cement. While I have moved on from teaching young engineering students, I have continued to mentor and advise entrepreneurs eager to use the technology, regardless of whether the application was really a good fit. I’ll expand on how the business case affects the use of 3D printing in a later segment.
Before you print, stop and think. Could I make this another way? Would that way be safer, cheaper or faster? Matching a design to a fabrication method is a critical step on the way to a great product.