Servo - August 2015

for mounting mechanisms and sensors.

The newest Runt Rover is the impressive Bogie, which is the other Runt we acquired for experimenting. The Bogie has six motors, six wheels, and a super cool rocker-bogie suspension arrangement. The Bogie towers over its fellow Runts with nearly five inches of ground clearance, and features a simple plate for mounting.

Runt Rovers Assemble

Now that we’ve become acquainted with the whole crew, we can take a deeper dive while we assemble the Sprout and the Bogie. First up was the Sprout. For starters, we laid out all of the parts much like is shown on the website. It’s a surprisingly small number of parts — only 13 individual pieces! Perhaps most surprising is that the Sprout actually requires no screws whatsoever — everything snaps together.

Just like with the grippers we worked with last time, the assembly instructions took the form of online videos. The familiar voice of the patient narrator takes you through each step, first identifying the parts you need and then showing exactly how things go together. The plastic parts all come with a rough edge and a smooth edge, so it’s easy to know if you have them in the right orientation. The snap-together parts strike the perfect balance between being easy to put together but snug enough to assuage any worries about the bot coming apart at the seams. It’s the perfect interplay, like between Johnny Carson and Ed McMahon.

Even the motors snap into the frame. The DC motors themselves are pretty impressive little packages. The motors are small and have a nice little gearbox attached to them. The output shaft from the gearbox is plastic with a flat edge, which fits nicely into the wheels that come with the kit. The motors even come pre-wired with nice solid pins on the end — not some frayed end of stranded wire. When it’s all said and done, the Sprout weighs in at just over half a pound.

One of the features of the Runt Rovers that are touted throughout the ServoCity website are the snap-on microcontroller mounts. The mounts are two U-shaped brackets with a stepped tooth-like structure on the inside curve. They looked simple enough, but the site ballyhooed them as an innovative and hassle free way to mount any of the popular microcontroller boards.

After testing them out ourselves, we are definitely believers. We slid an Arduino Uno in nice and easy by gently spreading the pliable plastic pieces. Once in place, the board was as solidly fixated as Lippy the Lion on one of his get rich quick schemes (despite the entreaties of Hardy Har Har). We could pick up and shake the Sprout, and the Uno board was at no risk of coming loose.

The unobtrusive mount also ensured easy access to every port and connector on the board. If we wanted to switch out the Uno for something bigger like a Raspberry Pi board, all we had to do was slide it out and affix the bigger board to the wider set of teeth. No more fiddling with posts and screws whenever you want to remove or install your board.

Once the Sprout was together, we were ready for the more sophisticated Bogie. The Bogie requires a few more parts, and entails screws as well as snap-together parts. At the beginning of the instructional video, it tells you what tools you need. For the Bogie, the video recommends a Phillips head screwdriver and a pair of pliers. The recommendation for pliers seemed a bit odd to us.

In the instructions, the pliers are used to hold nuts in place while the screws are tightened. A pair of pliers will indeed get the job done, but we preferred to go with a small socket wrench. Since we had the ideal tools at our disposal, we might as well use them.