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 Auto Parking Mecanum Robot

mecanum

A while back, Hackaday visited the Clark Magnet School in Glendale, California to sneak a peek on their STEM-focused curriculum, FIRST robotics club, awesome A/V classroom, and a shop that puts most hackerspaces to shame. We saw a few builds while we were there, but [Jack]‘s auto parking mecanum robot was in a class by itself. It deserves its own Hackaday post, and now that [Jack] is on Hackaday Projects, he’s sharing all the details.

The most impressive aspect of [Jack]‘s build is the mecanum wheels; the side plates for the wheels were designed by [Jack] himself and machined on his school’s Haas mill. When the plates came out of the mill they were flat, and each of the fifteen little tabs on the plates needed to be bent at a 45 degree angle. With a CNC jig and a lot of time on his hands, [Jack] bent the tabs for all eight plates.

In addition to the plates, the rollers were custom made from non-expandable polyurethane poured into a CNC milled mold. That’s a one-part mold; [Jack] needed to make sixty of these little parts, one at a time.

The electronics are built around an Arduino Mega communicating with a joystick via an XBee. [Jack] found the relays in the off-the-shelf motor board couldn’t handle the current, so he replaced them with much, much larger ones in a hack job we’d be proud to call our own handiwork. There’s also a little bit of code that allows this motorized cart to pull off the best parallel parking job anyone could ever wish for. You can see that and a few videos of the construction below.

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