Mark Ellis’ slightly-unsettling creation, the ‘Playa Crawler’ is making the rounds on DIY and maker subreddits.
A Redditor spotted Richmond, CA-based Mark Ellis trundling around the Maker Faire festival in San Mateo last weekend in his many-legged chair, and uploaded the video to Reddit, where it’s been posted across DIY and tinkerer subreddits. As plenty of Redditors have already pointed out, Ellis’ creation, which he calls dieselpunk, looks like something straight out of a Wild Wild West prop closet—specifically, the workshop of Dr. Loveless.
A Redditor spotted Richmond, CA-based Mark Ellis trundling around the Maker Faire festival in San Mateo last weekend in his many-legged chair, and uploaded the video to Reddit, where it’s been posted across DIY and tinkerer subreddits. As plenty of Redditors have already pointed out, Ellis’ creation, which he calls dieselpunk, looks like something straight out of a Wild Wild West prop closet—specifically, the workshop of Dr. Loveless.
Ellis told me in an email that the inspiration for the chair, which he dubbed the “Playa Crawler,” came from a combination of his love of the art cars (known as Mutant Vehicles) at Burning Man, and the work of artist Theo Jansen and his walking Strandbeest sculptures.
“I had never seen anyone take [Jansen’s] leg linkage and use it for a speedy personal vehicle and wondered if it was possible,” Ellis said. “I had seen it used on a machine called the Tin Spider which a large geodesic dome on top of the legs but it was too big for my purposes and it’s very slow. I thought it would be a better use of my time and creativity to make something ambitious like the legs rather than decorate a golf cart or build something over a mostly unmodded electric wheelchair.”
The chair is made mostly of aluminum, held together with steel rods. It’s powered by two 12v lead acid batteries, which run two large gearless and brushless motors that Ellis stripped out of an electric wheelchair, he said. “I don’t have much skill around electronics so I wanted to use something somewhat off the shelf that I knew would just work and then I built around those pieces.”
He’s gotten a lot of questions on Reddit, especially about whether it’s meant to be a wheelchair alternative and if it can handle rough terrain. Ellis told me he’s not a wheelchair user himself, so it’s not intended to replace a chair for someone who might need one, and that the legs are pretty shaky and don’t tackle inclines or obstacles well. “So far the Crawler only likes to walk on nice flat even hard surfaces like asphalt, concrete, or hard packed dirt which is very limiting for a normal wheelchair but for my purposes at Burning Man it’s perfect.”
Ellis plans to keep improving the chair, possibly turning it into more of a military-esque vehicle with fenders, headlights, and a retractable shade.
The Playa Crawlers first steps in the desert where it’s meant to be. It worked fantastically! The newer wider legs are really stable and resist bending and twisting. Before with the thinner legs the Crawler had a real hard time resisting lateral forces which meant that walking while tilted sideways on even shallow slopes meant the legs would bend in the way of each other but I think this version might do fine. The crankshaft is also really sturdy and the torque limiter helps keep the legs from being bound up and pushed to breaking by the motors. It’s not all perfect though. I need to add 1/4″ thick spacers on either side of the leg support plates over the crankshaft bearings to keep the crankshaft registered properly with the support plates. Without them the crankshaft has a tendency to get vibrated and pulled outward which made one of the pieces of keystock fall from its slot and cause a section of the crankshaft to break alignment. Also the through bolts that cause clamping force on the crankshaft drive rods might need to be replaced with course thread bolts instead of fine thread bolts. Two of the bolts got over tightened and stripped their threads and caused the crankshaft to shake apart because the clamping force went away. I think course threaded bolts might resist this problem a little better though I’m not 100% sure on that. Battery life is an issue too. The Crawler was able to make it from 3:00 esplanade to 9:00 esplanade and back (about 2 miles) but that’s the extent of the battery life on a full charge. I might experiment with lithium phosphate batteries in the future.
The Playa Crawler indeed
