After suffering what can only be classed as “multiple 3D print catastrophes”, we finally had enough components to start assembling our main chassis – consisting of two sideDrives, the piHelm, rigidDock and the steering attachment.
The sideDrive is something which we are very proud of and has taken quite a few iterations to land on the final design (even then we keep thinking of improvements for it). There are two main 3D printed sections one of which slides into the other and is held together by the pulley / belt configuration. The two parts can also be pulled apart to allow the sideDrive to extend by up to 5cm simply by using a longer belt and retaining screw.
With the motor needing to be fairly bulky to deliver enough power, we had to mount them perpendicular to the axle. To achieve this, we used the configuration of miter gears, pulleys and bearing mounted shafts to transfer the power to the wheel as can be seen in the video.
Once we had the sideDrives successfully assembled and tracked, it was finally time to attach them to the piHelm along with the most basic of the interchangeable Docks – rigidDock. The basic chassis that had been in the works for months was at last becoming a physical product – an exciting milestone.
One of the biggest challenges from a design and functionality perspective was the steering assembly. Alongside the sideDrive, this was the most prototyped and adjusted modules on the robot. The first complete design seen below proved the concept but was simply not smooth or rigid enough to be actuated effectively by a servo. The later design comprised an upper and lower ring of greased bearings to reduce friction and adjusted the connection from the miter gear shown below to a simple slot for the servo horn.
Initial steering connection 
The wheel inside the barrel 
The wheel hub inserted into the piHelm
Now that all the basic components were assembled, we could finally give it a test drive – albeit without functioning steering, but we had some fun with it nonetheless.
My next task…. Getting the sensors working!
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