My what big hubs you have!

With the work on the initial prop winding down, we're out of the garage and back into the shop. The milling machine will be the center of activity for the next few weeks as we churn out the custom drivetrain bits. We'll start with the drive wheels.

We decided to use 29" bike wheels as there is a good selection of heavy duty (tandem bike rated) components available. Unfortunately, we didn't feel like a standard width hub would give us the side loading strength we needed. Bikes lean for turning and thus other than asymmetric pedal forces, they don't get a lot of lateral loading. Narrow hubs work fine in that application, but our vehicle doesn't lean when it turns. Additionally, we need to transmit force to our axle whereas a bike hub rotates in its axle. The solution was to pick up racing kart wheels and modify them to create a hub that suits all of our needs.

We started by facing off the front and back of the kart wheels so there would be a flat area for the spoke holes.

With the wheel clamped to the index fixture, spoke holes were drilled every 20 degrees around the rim.

Here's a comparison with the original.