Living Hinges

Living Hinges aren’t just for CNC work, they can be 3d printed as well. Stereolithography files of models designed with hinges have popped up on various online printing communities.

Recently, I entered Instructables’ Lamps and Lighting contest with a project called Hinge Shade Empty Filament Spool Lamp. It features hinge pattern one from another Instructables post – Patterns Collection – for Bending Rigid Materials. I chose the pattern, thinking I could get a non-bordered print to bend in two directions. My attempt was unsuccessful.

Living Hinge Empty Filament Spool Lamp by Sandra James
Hinge Shade Empty Filament Spool Lamp

In an Instructables post entitled, Curved Laser Bent Wood, Aaron Porterfield shared his experiments with various hinge designs. He was searching for a hinge that was capable of bending in more than one direction and found one that could bend in a diagonal as well as parallel direction.

You can make living hinges in Inkscape by installing an extension. Once unzipped, the extension must be copied to Inkscape>share>extensions. Instructions on how to access the extension are given on this WIKI page.

I was curious about the history of living hinges and conducted a search. Google led me to patent 7,685,676 filed on February 24, 2006 for a living hinge. The patent was filed by W. Thomas McCellan, who passed away August 24, 2014. The patent expired on March 30, 2018 due to non-payment of maintenance fees; however, it can be reinstated. “If a maintenance fee has not been paid in a timely manner and the owner of the patent wants to get the patent rights reinstated, a petition and proper fees are required.” –United States Patent And Trademark Office (USPTO)

Image from patent application 7,685,676
Image from patent application 7,685,676

According to Justia, an expired patent falls into the public domain, but improvements on the patent may be covered by separate patents. “An invention covered by an expired or invalidated patent will fall into the public domain. This means that it can be freely used without paying royalties to the inventor. However, improvements to an invention in the public domain may be covered by separate patents that were obtained later and thus remain in effect.”

I saw a few patents filed within the last ten years connected to living hinges. One patent is for eyewear: “3D printed eyewear frame with integrated hinge and methods of manufacture.” Integrated is another name for living when it comes to hinges. The assignee for the patent is Materialise N.V., owners of i.materialise, the online 3d printing platform.

McCellan’s patent is set to expire completely around February 2026, but this cannot be confirmed by USPTO as they do not calculate expiration dates for patents. “In response to patent owner and public inquiry, the USPTO provides a downloadable patent term calculator as a resource to help the public estimate the expiration date of a patent.” All things considered, it does not appear that one can play fast and loose with creating designs that include living hinges, especially if it will be offered for sale, without checking with the patent office first.

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