How a Retractable Ballpoint Pen Works - Bill Hammack

Click. Click. The two clicks that you hear when pressing the top button on a retractable ballpoint ‘click pen’ are a key to understanding the mechanics happening inside of it: A rotation, extension, and lock of the spring-loaded ink cartridge, pushing the ballpoint tip into place outside of the casing. The two clicks that follow, the sound of pressing the button a second time,...

Plastic Injection Molding - Bill Hammack

Bill [Hammack] details the key engineering principles underlying plastic injection molding. He describes its history and then reveals the intricate details of the process. He shows viewers where to found, on any injection-molding product, the markings created by injection molding. He closes with a description of the one of the finest examples of the injection molding: the Lego bri...

The Cat Came Back - Directed by Cordell Barker - 1988

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