Who wouldn’t like to be hugged by a three-toed sloth?
Puppet maker, Randy Carfagno, had the idea for a sloth puppet and worked with Jim Polk to animate the sloth’s rather minimalist set of movements — head-turning and eye-blinking.
“The eye blink is initiated by a cam on the drive motor,” Jim explained in an email. “This causes a lever arm to pivot up and down. This arm transfers this movement via a parallel linkage to both eyes. The blink effect, a rapid return to the open eye position, is accomplished by means of a tension spring attached to the actuating lever arm. This brings both eyelids back up rapidly to the open position.”
“The neck rotation is a constant movement which moves the head back and forth about 45 degrees,” Jim explained. “The eye blink is on a momentary switch.” Jim worked with Randy to get the right effects into the space allotted. “The operator, who is wearing the sloth, can control it at will,” said Jim.
Kinetic Work
Jim Polk calls himself a “practical mechanician.” He has been focused on kinetic work since he began making wire sculpture as a teen. At the Rhode Island School of Design, Jim produced his first mechanical accompaniment to music. It was a sculptural performance piece made for Aaron Copland’s “Rodeo.” Then he worked for Atari as a model maker, where he began making test machines for the products they were developing. He went on to create test machines for other Silicon Valley companies as well.After Atari, he set up his own shop in San Francisco and began making mechanical toys.
Now, he is working out of his own shop in the Hudson Valley. Jim has built mechanical interactive exhibits for museums around the country. More recently he has gotten involved in special effects for theater and TV as well as kinetic features for architecture and product development as in the Atari days. The sloth project is an example of the work he’s done for TV, some of which can be seen in the video overview of his projects.
I asked Jim how he learned to do this kind of work. “I had one machine shop teacher at RISD that kicked my ass out of my teen age stupor and made me bear down on details,” he replied. “At Atari, I learned about dimensioning, precision machining and documentation.”
Another great learning experience was the year he spent at Mystic Seaport on a steamboat restoration project. “I took a year off from school to do this and it was another kick my ass and get to work experience that I needed at the time.”
The pandemic gave Jim an opportunity to dive in a bit deeper on another musical piece that will be accompanied by the song “Video Killed the Radio Star” and will premiere in the coming year. You can learn more about Jim Polk and Canstruct LLC on his YouTube channel, Canstruct.
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