Léo Solé — November 28, 2017
How can 3D printing help designing a device
After settling on a design it is important to make sure the device you’re creating perfectly matches its intended purposes. That’s when we used 3D printing, and we’ll share with you how it has helped us.
What decision can you make from a 3D print?
The greatest upside of 3D printing is that it lets you manipulate a device you had only seen on screen or paper. Once 3D printed, you can physically handle it, check its actual proportions and simulate future use cases.
That was the case with our calculator. 3D printing allowed us to validate the intuition we had regarding the overall usage of the protective cover. Playing with a 3D printed prototype, we could check that it was indeed easier to slide the case open, and even easier to close it by clipping the cover instead of sliding it back on.
Checking the device’s proportions is also a great benefit of 3D printing: on a device such as our calculator, we could physically experiment with the key spacing, which is obviously impossible to do on a screen. We printed several variations of the keyboard and settled on the most usable option.
What are the shortcomings of a 3D print?
Unfortunately, 3D prints aren’t accurate representations of a real device.
Indeed, 3D printed prototypes don’t have the same mechanical characteristics as the final product, no matter the 3D printing technology used (fused deposition modeling or stereolithography). For example, we couldn’t try assembling 3D printed parts using screws as those would have broken the fragile 3D-printed screw holes.
Picking the right material is very important. On some prints, the low rigidity of the material lead to twisted parts. It can be very useful to pick a material that closely matches the final product’s. To check the protective cover’s functionality, we picked a material whose rigidity was very similar to polycarbonate.
Why bother with 3D printing then?
If the quality of 3D printed parts is so different from the final one, you could ask “Why bother? How about asking the factory for prototypes?”.
Most plastic parts are made using injection molding: molten plastic beads being injected in a steel mold. Each part being specific, one need to build a mold for every single part. And those molds are very expensive (tens of thousands of dollars) because they need to be very resistant and accurately machined. It therefore makes sense from an economic standpoint to use every other method available to limit the number of molds created.
As an alternative to 3D printing, it is also possible to machine prototypes parts. Starting from a block of plastic, material is machined out until the requested part is obtained. This is more expensive and slower than 3D printing, but the mechanical properties are very close to the final product.
Fuzzing a calculator!
"Beware of bugs in the above code; I have only proved it correct, not tried it." — Donald Knuth
Émilie Feral — January 04, 2018