THP Entry: A Holonomic Drive 3D Printer

holo

[Sugapes] always wanted to cut a few corners and build a really, really cheap 3D printer, but the idea of using linear actuators – pricing them, sourcing them, and the inevitable problems associated with them – scared him away. One day, he realized that moving in a plane in the X and Y dimensions wasn’t hard at all; cars and robots do this every day. Instead of moving a 3D printer bed around with rods and pulleys, [Sugapes] is moving his 3D printer around with wheelsIt’s different, it’s interesting, and it’s the perfect project to show of his creativity for The Hackaday Prize.

The drive system [Sugapes] is using is called a holonomic drive system. In his build, three omnidirectional wheels are attached to continuous rotation servos, each of them mounted 120 degrees apart. The print bed is simply placed on these wheels, and with the right control algorithms, [Sugapes] can move the bed in the X and Y axes. With an extruder on a Z axis above the bed, this setup becomes a 3D printer with a theoretically unlimited XY build axis. Pretty clever, huh?

There are a few problems [Sugapes] will have to overcome to turn this project into a proper printer. The omnidirectional wheels aren’t the best at transferring movement to the bed, so a quartet of USB optical computer mice are being used for a closed loop system. [Sugapes] put up a video of his project, you can check that out below.


SpaceWrencherThe project featured in this post is an entry in The Hackaday Prize. Build something awesome and win a trip to space or hundreds of other prizes.

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The Hubless Horseman

hublessHorseman

Of all the free parts up for grabs at a friend’s house, nobody wanted the scrap wheelchair wheels: including [Eric]. That is, of course, until he spontaneously decided to try something a bit crazy and take on a bizarre yet remarkably imaginative hubless wheel bike build.

After attaching the wheelchair’s rim and its affixed handrail to the rim on his bike, [Eric] mounted pairs of rollerblade wheels to a separate piece of metal that essentially act as bearings. As the build progresses, the bike is further refined. More rollerblade wheels, a giant sprocket, and a pile of machined aluminum pieces. The valve stem for the tire had to be relocated to allow the wheel to spin freely.

The finished product is a stunning bicycle, which [Eric] later revisited, updating the rollerblade wheels to precision-lathed plastic (specifically UHMWPE) rollers. Make sure you watch the video of the Hubless Horseman in action. If, for some reason, your only prior exposure to hubless wheels is the TRON light cycle or [Kirk's] motorcycle from the Star Trek reboot, do yourself a favor and check out their inventor, Franco Sbarro.

Slick robot with tank treads can move every which way

omnicrawler

It’s always interesting to see new and innovative means of robot locomotion. At the recent “Innovation Japan 2011” conference researchers from Osaka University unveiled the Omni-Crawler, which is aimed at changing the way both robots and people move.

The Omni-Crawler’s movement is provided by Omni-Balls, an Osaka University creation that moves in all directions, not unlike a swivel caster. The Omni-Ball is simpler and sturdier in design however, making it far more robust than its office chair counterpart.

Several of these Omni-Balls are attached to the crawler, and wrapped in a rubber tank tread like gripper material. The resultant motion is predictably omnidirectional, though we’re guessing you figured that out already thanks to Osaka University’s naming conventions.

While we’re not sure this technology will be making it into production cars any time soon, we would certainly be OK with having an RC Omni-Crawler to play around with in the office.

Stick around after the break to see a short video of the Omni-Crawler in action.

[via BuildLounge]

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Hubless inline skateboard


We’ve been talking a lot about alternate modes of transportation lately. The 360 inline skateboard immediately caught our eye for its simplicity and hubless wheel design. The usage seems fairly straightforward, but the videos posted by designer [Francesco Sommacal] don’t make it look exceptionally fun; more like they’re daring you to use the thing. What we find most jarring about this is how similar it is to the Bushpig. Did the commercial gas powered version really predate this unpowered device?

The design is simple enough to understand, but we’re not really sure where you can easily source hubless wheels like this. Any ideas?

[via Gizmodo]

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