I am in the process of building my first ESK8, and I am very interested in fabricating my own precision trucks and hub motors much later down the road. I have built 3D printers, drones, and other projects in the past, and I recently taught myself how to use Fusion 360, so I have some amateur experience with engineering and fabricating. I am creating this topic to share my ideas, designs, and to take advice and inspiration from other ESK8ers who are perhaps more experienced than I am.
My goals for this project are:
- Create precision trucks that are designed with ESK8 in mind and hub motors to go with them
- Build upon and address issues with current truck and hub motor designs
- Share my designs with the public via thingiverse.com
- Design with the amateur hobbyist in mind, so that anyone with access to a metal CNC mill can make it themselves
My current ideas for this project are:
Make precision trucks that use the same bushing and pivot cup dimensions as an existing precision truck (possibly Surf-Rodz RKP) so that instead of having to make custom bushings of dubious quality, people can buy bushings from a tried-and-true manufacturer like Riptide.
Make Hummie style hub motors rather than Carvon style motors. I know this is a FIERCE topic of debate in the community, but I want to go with Hummie style hubs. Here’s why:
Stress is more evenly distributed across the motor
They make use of space much more efficiently
It seems like just about everyone in the unpowered downhill scene uses much shorter width trucks. I think having shorter trucks might increase stability at high speeds, because it essentially makes the wheelbase longer relative to the truck width. Also, the longer your trucks are, the more your leaning is converted into turning, which can lead to instability. I think we can learn a lot from the guys going 50+ mph. How does this relate to hub motors, you might ask? Well, with Carvon style hubs, the trucks need to be SUPER wide to accommodate the motors in between the kingpin and the wheels. But with Hummie style hubs, since the motors are in the wheels, you have a lot more room to shorten the trucks.
Stealthy as fuck. Not nearly as important as the other things listed, but I know some people care a lot about looks.
As for the issue with thin urethane on in wheel hub motors, I think there is an easy fix. Bigger wheels! Why stop at 90, 97, 107mm? Since in wheel hubs require casting urethane, why not use that as an opportunity to cast some bigass wheels? I’m thinking 120, maybe even 130mm. That would allow the motor to be bigger as well, which would increase power and cooling.
Make the truck a giant heatsink. The biggest issue with in wheel hub motors is that they have a hard time cooling down. Duh. You can’t stick a motor capable of pushing a human being over long distances at speeds over 30 mph in a nice blanket of heat insulating urethane and expect it to be cool as a cucumber afterwards. So why not make the truck a giant heatsink? After reading @Minim’s awesome post about his custom Raptor 2 hangers (link: https://www.electric-skateboard.builders/t/raptor-2-custom-hanger-for-better-cooling/61104) I had a eureka moment. USE THE TRUCK AS A HEATSINK! Minim had to design the hangar to be compatible with all of the Raptor 2 measurements, but if I am making trucks/motors from scratch, I can design it to be one large, incredibly effective heatsink. Perhaps I could use thermal paste where the motors attach to the hanger to augment the heat transfer even more.
Anyways, those are my ideas so far. If you have any suggestions or advice, please comment below.