Scrap Wood and Metal Combined for DIY Mecanum Wheels

Some scrap wood, a few pieces of sheet metal, a quartet of old gear motors, and a few basic hand tools. That’s all it takes to build an omni-bot with Mecanum wheels, if you’ve got a little know-how too.

For the uninitiated, Mecanum wheels can rotate in any direction thanks to a series of tapered rollers around the circumference that are canted 45° relative to the main axle.  [Navin Khambhala]’s approach to Mecanum wheel construction is decidedly low tech and very labor intensive, but results in working wheels and a pretty agile bot. The supports for the rollers are cut from sheet steel and bent manually to hold the wooden rollers, each cut with a hole saw and tapered to a barrel shape on a makeshift lathe. Each wheel is connected directly to a gear motor shaft, and everything is mounted to a sheet steel chassis. The controls are as rudimentary as the construction methods, but the video below shows what a Mecanum-wheeled bot can do.

There’s a lot of room here for improvement, but mainly in the manufacturing methods. The entire wheel could be 3D printed, for instance, or even laser cut from MDF with a few design changes. But [Navin] scores a win for making a working wheel and a working bot from almost nothing.

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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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Robot bicep curl accompanied by too much fanfare

So this is the world’s strongest robot arm. Great… no really, that’s wonderful. We think lifting a 1000 kilogram dumbbell is a good way to show it off to the public. But with great power came the world’s most over-the top marketing. Well, maybe not as bad as the shake weight but it’s getting there. In the video after the break you’ll see that there is plenty of adrenaline-pumping music and they’ve hired an acrobat to pull a sheet off of the thing. We’ve pointed her out in the image above. [Caleb] noticed that they seem to have programmed in human kinetic to make it bounce and strain as a human lifting a heavy load would. And then there’s the fog machine. Classic. We also enjoy the use of a tap light (which we’ve seen around here before) to activate the demo.

But now we’re getting carried away. The article linked at the top covers a new development for the arm; a motorized base that can move it around. Looks like the base, which uses mecanum wheels, just slips under a stationary frame for the robot and lifts enough to truck it around.

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Printable mecanum wheel

[Zaggo] developed a printable mecanum wheel. These are designed to allow a wheeled vehicle to move in any direction. He uses parts printed with a Makerbot along with commonly available bearings, bolts, washers, and nuts. Download the STL files need for printing and watch the assembly video after the break. We’ve also included a clip of an unrelated robot project using mecanum wheels so you can see what [Zaggo] will have once he fabricates the rest of the of the wheels. Continue reading “Printable mecanum wheel”