The importance of building prototypes. It sounds like a simple and obvious concept, but it is more complicated than it seems. In the years I have been doing product development, this is one of the most important lessons I like to pass on to new engineers. Having hand built thousands of prototypes over the years, there is nothing more valuable than assembling your own designs. Here are a few important guidelines to follow when building prototypes:
A major problem when designing in CAD is the lack of scale. A small 1.0mm feature can look huge on the screen but in real life, it is basically microscopic. The best way to give yourself a sanity check is to 3D print things as often as you can afford to do so. A good rule of thumb: if a feature is too small to print, it’s too small to mold.
Build many, many, many prototypes
Don’t just build one prototype; build five or ten or fifteen (if it's financially acceptable). When your design is at a stable point it's best to build a bunch of them. This is where hand building comes into play. A lot of the time it is easy to unconsciously overlook difficulties and design flaws since you are so close to the design. You know how it “should” go together, so pay close attention to what you are doing at every step, taking notes on how things fit and how many times you need to flip the part. If you want to take it to another level, videotape yourself and re-watch it. Remember, if it is difficult for you, it will be difficult for everyone else as well.
Watch someone else build it
If you are lucky enough to have interns, this is the perfect job for them. If not, use your marketing, finance, or any non-technical person on your team to assemble it. Whoever it is, watch them interact with the product while giving minimal instruction. This will point out assembly pain points very quickly. It will be frustrating to watch (trust me) but a great source of knowledge.
During any of the time you (or someone else) were assembling the product, did you ever wish you had a third hand? This is where fixturing comes into play. Determining where in the assembly process you need a fixture prevents a lot of headaches later on. If you are in the factory and realize you need a fixture, it’s way too late. Create a small set of requirements for each fixture to supply to the manufacturer along with samples at the proper build stage. If you are assembling everything at home, you don’t have the ability to CNC custom holders, but using simple model clay is a great place to start.
All of this building isn’t a waste. Use the prototypes for testing, marketing samples, or just give some to friends. I have never regretted building excess prototypes and neither should you. Just remember to budget for prototypes, at least five per build cycle, ten if you can afford to do so.