Summer Robotics Project #3 – CAD & Banebot Wheel issues

Below is the current CAD model of the robot. As we build the robot, we modify the model to match the positioning of the different components.

In order to create the model, we designed the different parts of the robot as separate parts on Solidworks, and then put everything together in an assembly. Some of the models, such as the Arduino UNO and Raspberry Pi were downloaded via open source websites such as GrabCad.

CAD Model

In the model above, you can see the Banebot wheels we have decided to use for our robot. (We’re using 3-7/8″ wheels, but the ones in the model are slightly smaller). However, we came across a problem with the wheel set we had been loaned. The thread on the screws, that are needed to hold the wheel hub onto the motor shaft, had been worn out so much that it was next to impossible to screw them in. Even when we did manage to screw them in, after a few rotations, the wheels would fall off the shaft.

As we are currently unable to travel back to Southampton to get a new set of wheels, and because we didn’t want to purchase a new set ourselves, we decided to order in replacement screws. We measured up the hole diameter, and from testing different screws, we noticed the M3 screws we had fit, but the diameter was too long. We ordered in some M3 x 4mm screws, in the hope that these would be the right size. But once we had received them, we noticed they didn’t fit; the thread diameter ended up being less than the hole’s diameter. After conducting some research, we found out, that because Banebot is an American company, the dimensions of the screws were slightly different and the actual screws used were 6-32 1/8″. We found it difficult to source this, at a cheap price, within the UK but eventually came across a set on Ebay, which we hope will be delivered soon so that we can finally mount the wheels and test the robot properly.

Despite this issue with the wheels, we continued working on the robot. We managed to test the LCD display and the compass, which I will talk about in more detail in tomorrow’s post.

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