Decided to build another tank with a smaller chassis and with motors that were geared lower. The primary control of this tank will be with the PS3 Game Controller.
This tank differs from the previous in that is has a much smaller foot print and is made entirely of metal (aluminum). Because of the smaller footprint it became more difficult to design. I had to go “up” to create space and this created a higher center of gravity then what I wanted.
One thing to consider before buying this tank: it is made from laser cut stock and comes with a blue peel film. The film removes easily but there are some very small metal fragments from the cutting process. These can easily find a way into a mouth or eye and in the case of an eye cause some serious damage. Here is a pic of what I am referring to (these pieces are very small a literally paper thin). Also some of the edges are sharp. This would not be a “best” choice for kids.
I will provide a quick build scenario and highlight some points of interest.
The unassembled kit. Comes with a large selection of screw, nuts, bolts and some very small hex screws used to mount the drive sprockets. These hex screws are easy to loose so separate them out from the rest and put in a separate zip log bag for future use.
Like in the previous build I recommend the use of lock washers when attaching the wheel assemblies to the side panels/frame (not shown here in the initial assembly).
I had purchased an open Pi2 case and used two of the 5 pieces that came with it (the bottom and middle piece shown here. The top most piece shown here was fashioned by had from an 8×10 piece of Plexiglas. Having a Dremel drill press will be of great value when duplicating the M2.5 and M3.0 holes. The very top board is the PiborgReverse Motor controller. It is important to note the black, red, and white wire bundle coming off of the Pi2 header. There must be sufficient clearance between the header and the top piece of Plexiglas to accommodate the 2 3wire bundles.
This chassis was a pain to work with because it is too small. I needed to accommodate 3 power sources (battery packs, one for the Pi, one for the motors, and one for leds not shown in this build). What I ended up with is shown to the right. Notice the 8X2AA battery pack mounted beneath the base plate and suspended by extruded aluminum rails. The battery pack for the Pi will be on the main platform in the narrow region between the vertical standoffs. A note on soldering the motors. Take a motor and mark it LM (left motor) and mark the other RM. Why? because while these motors have their electrical connections correctly marked “+ and –“ one of the motors must be wired in reverse or else when you apply power the tank will spin circles. Just thought I would point this out.
The build of this tank is fairly straight forward from a software perspective I refer you to PiBorg UK for the build instructions and you can of course refer to my other build for the Bluetooth and PS3 install. You will need to download the software from the PiBorg site in order to mate to their motor hat.
I must admit that while the crawler was a pain to work with because of its small foot print it is absolutely easy to control due to the lower gear ratio on the motors. Its not as fast as the first tank I build but has more power. The Piborg software is also quite robust. Here is a video:
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