I needed a platform to try out the Dagu Explorer robot control board. So I built one using a plastic plate from an old CD Rom drive, a couple of geared motors, wheels from a “Turbo Diesel” dump truck toy (a knock-off of the Tonka Dump Truck?), and an Arduino UNO.

I made a platform from the plastic base plate of an old CD Rom drive, cutting it to about the same length as the Explorer board, so that the corner infra-red sensors would over-hang the ends. This was a mistake! It turns out that the sensors are easily bent in collisions, and it would have been better to have them slightly behind the corner edges of the base plate.

Originally I was going to use a broken toy dump truck as the platform, but the Explorer board didn't really fit (and the corner sensors wouldn't have been any use). So I ended up just using two of its wheels.

The two, 45 year old, 6V geared motors were bolted to the plate and a single old furniture castor wheel was mounted using old Meccano L brackets on the front. The geared motors were bought to use in building a toy long before micro processors or micro controllers were ever invented, but never used. They have an adjustable gearbox that allows selecting gear ratios from 3:1 to 16:1. The wheels were mounted on the axles with their outsides facing in. As the hubs were recessed this allows the gearbox on the end of the motor to fit inside. This results in the wheels being mounted on the axles closer to the platform (the gearboxes extend beyond the edge of the platform).

The castor wheel has a ball-bearing axle, so rotates freely and is capable of operating with a far greater load that this robot will ever impose on it.

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