Various features of the tank are seen and discussed:
The whole idea of the tank was to test out my design of suspension and thus is the main mechnical focus here. As we can see below, the largest section of the tank is the suspension.
1)Starting off we have the road wheels, since this was a testbed I only needed the wheels to elevate the whole chasis off the ground just enough to pass through most everyday house objects which was approx 20mm. this meant the wheels need only be 20mm in radius as you typically can only climb items the same height as the diameter of your wheel, fortunately the tracks might help me cover a bit more to 35mm should there be enough grip.
2)Next is what the wheels are connected to, suspension:
As I needed to dampen the effect of making contact on the ground I also needed a form of suspension that could be easily replaced and sourceable, my conclusion would be to use rubber bands. Unlike most suspension systems that uses a spring, I had to use a rubberband therefore I had to work around using tension instead of compression which meant a class 1 cantilever. A class 2 or 3 could not be used due to the lack of space and I could make the build very fragile if I did not design it right.
2.5)Each individual component of the suspension consists of these:
Looking at the wheel first, we see that it's connected to the outer suspension and held in place via a washer and nut. When actuated, the outer suspension in turn turns the inner suspension which pivots within the chasis. This results in the groove of the suspension to displace which stretches a rubberband within it that is also anchored to a peg. The inner suspension and peg are kept in sync by the guide as the whole assembly moves and of course where the groove is present the inner suspension moves within it. There is a stopper to prevent the suspension from snapping shut onto the peg.
Which are assembled as such:
Should be noted that the peg has a chamfer along the outer face to allow the outer suspension to flow smoother:
3)Now to talk about the thing that keeps everything in order, the track tensioner
As most tanks have track tensioners I thought it would be a good idea to implement my own as well in a worm gear style, this helps to minimise backlash whilst remaining easy to operate. In this case because I was short on time therefore I had taken a design from a user on thingiverse which consisted of the rail, worm gear and housing for the gear. I had modified his design to fit my own needs which shortened the rails, resized the holes, adding a stabliser for the free wheel and cutting off bits of the worm gear whilst making an insert that allows for a flathead screwdriver to turn it.
Here is an exploded view:
4)Last but not least, the running gear:
The powerhouse of it all is the motor which is mounted on a housing which is in turn mounted to the main chasis as seen here.
The mount is designed in such a way that I can mount almost any continuous stepper motor
The running gear was actually based off someone else's design that I got from thingiverse. However, I had heavily modified it. As shown here it has 4 holes and slots coming from every 90° lined up perfectly to create a 4 anchor points. it also has a giant cavity to reduce weight, bulkiness and print time.
