CIM Motor Direct Drive or Supporting Axle

[loganc10]

Good day,

Over Christmas break, I plan on building an automatic tennis ball thrower for my parents dogs. I have purchased two CIM 12V motors as the two spin wheels that will launch the ball.

It will be very close to this project here. Youtube Project

Here are snippings from the above video.




I'm finishing up my bachelors in electrical engineering in the spring, so the electrical side of the project I competent in. However, the mechanical components of the system I am slightly struggling with.

I ordered two 8mm set screw hubs that I planned to use to hook my wheels directly up to the CIM shafts. However, looking closer at the above design, I noticed that it uses some sort of axle that is supported on the other side of the wheel. Is something like this absolutely neccessary?

I am not 100% sure what type of wheels I will be using, I am debating either lawn mower wheels or cutting and layering circular sheets of plywood then bolting those to my hubs. Below is the lawn mower alternative,

I'm not sure how I would attach these to the hubs though.

Thanks,
Logan