Devlog #4: Finishing CAD and finalizing materials/parts

I might not have mentioned this earlier but my goal for this project has been redirected: I want this kart to be a lightweight, weldless, easy to build (no machine shop tools required) and cheaper version of the Razor CrazyCart XL.

What I did

I finally finished the CAD, adjusted spacing for everything so I would actually fit, finalized the exact parts I need to order for the kart, and did finite element analysis to make sure the frame wouldn’t fail under my weight.
One problem I ran into was that speedymetals.com, the place where I’m getting my metal, only has square tubing in 6063-T52 aluminum, which is much weaker than 6061-T6 which would have been much more preferrable. I was concerned enough that I ran a finite element analysis to ensure that the frame wouldn’t buckle, and after testing 1.5x the load the frame would bear, I ended up with a factor of safety of 2.89, which should be more than enough to bear my weight. I also designed a couple of jigs to help with hand drilling and sawing the aluminum.

What’s next

I am going to finalize the BOM and GitHub and submit this project for funding.

Devlog #3: I suck at CAD

What I did

I spent basically all of this time modeling and assembling the parts I am planning to use for the kart. I probably went into too much detail in the process, but I wanted the model to be as close to what I am actually building so I don’t waste time and money.

The parts that took the longest by far was the frame/head tube and the front fork. For the fork, as many of the dimensions were not accurate to the picture on the Amazon page, I had to adjust the dimensions many times for the wheel to actually fit. I also had to move some stuff around to minimize my ground trail so I can steer with as little effort as possible. The head tube took a ton of time because I had to take measurements by hand with a ruler, and I wanted to make extra sure they were accurate.

I really need to work on separating parts and assemblies, for a lot of these parts/assemblies I’m using a hybrid design (designing parts and assembling them in the same file) out of laziness and it gets really disorganized sometimes.

What’s next

I actually hope to finalize the entire CAD next and create a BOM so I can submit this project for funding.

Devlog #2: More CAD and design changes

What I did

The majority of the time I spent for this devlog was just CAD, but a decent part of it was googling and asking ChatGPT questions.

Powered wheel module (PWM)

After finishing the frame and starting the front steering/powered wheel module, I realized that welding my own steering fork that could hold a motor and the wheel would be both expensive and turn out crappy. After doing research on alternatives, I came across the hub motor wheel: an expensive but much simpler and more compact way to power my kart. With the hub motor, I would no longer need to chain a motor with a wheel, which would’ve been many moving parts that I would need to maintain. Pairing this with a commercial e-scooter front fork, it would save me tons of headache with gearing, chaining, welding, etc. To add on another benefit, I already own an e-scooter frame with a head tube that is compatible with the front fork I am planning to get.

Drift bar mechanism

After solidifying my plans for the PWM, I started designing the drift bar mechanism. The Razor Crazy Cart drift mechanism consisted of one big pipe in the back, supported by two pillow block bearings, with the caster wheels, hardstops, and a compound lever all welded on. However, I want to minimize the amount of welds I need to do for this project as my access to a welder is quite limited. After doing some research, I came across the single socket tee: a pipe fitting that allows me to attach pipe perpendicular to the main back pipe with set screws. Since set screws are pretty weak, I also plan to use through-bolts with lock nuts for additional strength. Using this, I can have one rotating main pipe on the back and securely attach the two casters, hardstops and a drift lever (which I’ve modified to just be a simple second-class lever.)

What’s next

I hope to finalize the entire CAD next and create a BOM so I can submit this project for funding.

Devlog #1: getting from idea to model + figuring out the frame

Idea

While I was procrastinating brainstorming project ideas for this challenge last week, I came across a video of that one spinning cat that goes o i i a on my Instagram reels. A couple reels afterwards, I got an ad for a Chinese-produced drift kart, and I realized that combining the two would make for a pretty cool summer project.

Preliminary sketches

I started off by doing some rough drawings of what I wanted to build and figuring out the most technically challenging part of the build: the drift mechanism. The kart doesn’t drift conventionally; it acts more like a powered caster cart.

First steps + what’s next

After figuring out how everything worked, it was time to CAD. For now, I cadded out a preliminary frame. For the future, I need to figure out the spacings for the steering/powered wheel module and CAD the rest of the chassis.