June 2011
47 posts
Lead up to our deadline
With our deadline coming pretty quickly we all spent most of this week working furiously away in the workshop.
Haydn and I, with assistance from John the workshop technician, painstakingly cut mounting holes for our motor, wheel and other parts to great accuracy.
Damien amputated parts from the kids donor skateboard and reinvented the clip system so that we could attach and detach the motor.
...
Hubless wheel design issues
With the CNC router unavailable, and unlikely to be able to cut through our metal anyway, we’ve had to look at alternatives.
Haydn, Jason and I went to Massey’s Industrial Design school and talked to their workshop technicians about using Massey’s waterjet cutter. Nick has a circular piece of lathe alloy to produce the internal ‘hubless hubs’ from.
It would be...
Time Pressure
At this point we only have a couple of days left to finish this project. We’re working hard to pull all the parts together.
Haydn and I have made a couple of prototypes of the motor and gear housing on solidworks and then in cardboard.
Currently, Nick is machining alloy wheel rims, with John the workshop technician running the CNC Haas machine to produce the Urethane wheels.
James is...
Hubless Wheel Material and Components
The components and materials for the hubless wheels are all sorted.
We had three options for the bearing sizes which are:
Bore - OD - Width
90 - 98 - 30mm $125.00ea
95 - 103 - 30mm $95.50ea
100 - 108 - 30mm $75.15ea
The prices for the bearings are quite expensive, mainly because it’s not that common to use these bearings for large applications, they’re...
Batteries again.
We need 36V worth of batteries to power our board.
We want a good weight to power balance. NiMH batteries could be the solution to this problem. Sourcing these batteries is not a problem, finding a 36V charger for these batteries is. Ideally, each individual cell should be charged equally and separately. A 36V charger could damage the cells.
For the purposes of demonstrating our board we think...
Nigel Vining, founder of Greenskate
Greenskate.co.nz has, so far, been our point of reference for electric skateboards in NZ. They almost exclusively are the only online retailers of electric skateboards, outside TradeMe.
I bought a motor controller from Greenskate. Nigel Vining, founder of Greenskate, agreed to meet up with us in Wellington City to give it to us and talk skateboards.
Nick, Damien, Jason and I met Nigel in town....
Batteries
Our skateboard requires a pretty decent output power, and a motor will draw a lot of current.
We need some decent, compact batteries that are high capacity and have a high energy density.
At the lowest level are SLA, Sealed Lead Acid, batteries like your car battery. They’re cheap, low maintenance and high capacity, but are heavy and very bulky.
At the top of the range are LiFePo4,...
Testing and reverse engineering
Nick, Haydn and myself met earlier in the week to test, and reverse engineer the electric skateboard and scooter.
We rode the scooter around town, getting a total distance of about 3km before the power and speed of the scooter started noticeably fading. It struggled up inclines, but was pretty quick on slight downhill slopes. Its average speed is about a brisk walking pace - light jog. At full...
Solar regulator
Earlier in the week I spent some time with Peter, the electrical technician, developing a solar charger circuit. He introduced me to a pre-packaged power regulating chip that would do the job fine. The output voltage could be adjusted by an arrangement of capacitors and resistors.
Safety first
http://www.stuff.co.nz/national/3272929/Motorised-board-death-reignites-helmet-debate
An article on stuff discussing the need to wear helmets on an electric skateboard.
Hub motors
When we considered the drive wheel, we have to consider the placement of the drive motor. An in-hub motor would be discrete and out of the way. There are motors on the market that are already geared of free-wheeling. A hub motor would allow us to have a more minimal design. A free-wheeling hub motor would allow the skateboard wheels to move freely when not powered. This means that after our power...
“Your skateboarding days may be long gone but these are becoming a viable option...”
– http://www.nzherald.co.nz/environment/news/article.cfm?c_id=39&objectid=10518993
Sourcing Parts
At this point in our project we are having difficulty sourcing parts.
There is a delicate balance in getting the right parts for the job…
More batteries bring more power, but also more weight and size.
Solar panels that would fit our requirements are very expensive, large and bulky. Plus, the size of the panels are constrained by the size of our board since we want to have them mounted to...
Hubless wheel
Ok, I’ve wacked out a CAD model of how I think the hub less wheel is going to work. it’s quite a simple design which utilises a needle roller bearing. The name of the bearing pretty much explains it, having needles that roll around in a cage. The main advantage of using a needle roller bearing is that it’s got a slim profile, it’s minimal bearing thickness means we can...
May 2011
34 posts
Summary of our project
Revised Idea:
We plan to design and create a personal motorised skateboard transport system, which is powered by solar energy when not in use.
It will be safe enough to be used in most public spaces and stable enough that a wider range of people might consider using it, not just the typical ‘young and fit’ skateboarder.
It will be able to be stored or parked in such a way that it...
