Eyeing a better hinge

This 3D-printed hinge came out of the build chamber operational.

It’s maddening to try to fix the hinge on a pair of eyeglasses with a screw from a discount store repair kit. I know this to be true. The screw is too big. Or too small. Or it disappears into the carpet or sticks to my thumb.

Additive manufacturing may save future generations from this onerous task.

I learned that eyeglasses hinges are a good AM candidate during a recent telephone interview with Desktop Metal co-founder and CTO Jonah Myerberg. While discussing the company’s new 3D printer for mass production, he said the eyewear hinge is a “great example of what’s to come in 3D printing. The reason parts exist in assemblies is because there’s no other way to make assemblies. If you print the assembly, you lower the part count.”

And the fewer parts an assembly comprises, the less likely the product—eyeglasses, for example—will fail.

An interesting aspect of the build is that the pin the hinge’s two leaves revolve around was printed in situ. And, the hinge was operational right out of the printer. No post-printing work was required.

High-quality build materials are important to ensuring high-quality, finely detailed 3D-printed parts. The powder used to print the hinge has a particle-size distribution of 3 to 20 microns.

“We print at a 20-µm resolution,” explained Myerberg. “This means we leave voxels untouched, and when they’re untouched, you can just shake the excess powder out of the [hinge], because it does not fuse with the rest of the part.”

Desktop Metal, Burlington, Mass., built the hinge to demonstrate the capabilities of its Production System 3D printer, the first of which is scheduled for installation in the first quarter of 2019. A press release from the company notes that the machine could print more than 45,000 pre-assembled, 12- by 5- by 6-millimeter eyewear hinges in a single four-hour build.

That type of output would be a good step toward lowering the frustration level of generations to come.

Desktop Metal CTO Jonah Myerberg.