This is my first esk8 build. I had a build thread on the other forum before it was shutdown. I thought I had completely lost it, when suddenly the site started working for me last night, so I grabbed a copy to put on esk8.news.
I’m copying the format for presenting specs from @donta42
- Deck: Custom billet aluminium deck machined by Datron at a tradeshow in 2018. Kindly gifted to me.
- Enclosure: Custom CNC enclosure made from bamboo shelving.
- Trucks: Modified Paris RKP 180mm
- Wheels: BKB 97mm 78a
- Battery: Custom-built 10s3p Sony VTC4 pack
- ESC: Enertion Focbox with separate Bluetooth module
- Motor: BKB 6354 208KV
- Board total weight with battery: 20.5lbs / 9.3 kilos
- Rider stats: 65kg
It all started when I was given a beautiful longboard deck at a manufacturing tradeshow called IMTS in Chicago last year (2018.) It was manufactured from a solid piece of aluminium plate, on a Datron CNC machine. There is a pattern machined into the top surface, instead of grip tape. The guys at the booth told me they’d give it to me, if I’d post some pictures of it on Instagram when I got back to where I live in New Zealand. Of course I agreed, and on the spur of the moment, told them I’d turn it into an electric longboard, which they were very interested to hear. At that stage, I knew nothing about the ESK8 community and had never ridden an electric board. It was time to get googling!
Here’s the starting moment of the project:
I looked around for trucks, and read some threads in this community. Decided to use either Paris or Caliber trucks, and I could get Paris locally easily, so I went with them. I thought they looked nice on the board, and thought the round section of the hanger would be handy for mounting the motor.
Wheels were a tough decision. I looked at all sorts of options, and decided the Evolve street kit would be a great way to get wheels, pulleys and belts all in one go. While they look like a really nice product, when I received them and started to plan the fitting, I realised they would take up too much width on my trucks, so I sent them back. Luckily, the shop I got them from was very helpful and refunded my money happily.
I then discovered https://buildkitboards.com/ and I was like a kid in a candy store. I got some of their 97mm black wheels, with their interchangeable pulley setup, as well as a bunch of other stuff which you’ll see further down.
The wheels looked really awesome on the board, and with just a little bit of turning on the lathe, I was able to modify the rear truck to get a hobbyking motor mount sitting nicely.
This was the early stages of the CAD model. If any of you using Fusion 360 for design, let me know your Autodesk ID email and I can add you to the design if you like. If you don’t know about Fusion, it’s an awesome design and manufacturing tool that is completely free to hobbyists and education.
Designing the battery pack
Bought some used cells from http://hipstar.co.nz Tielman was super helpful, answered my questions and gave me all the info I needed. They’re Sony VTC4 cells, which he recommended because even though they have a fairly low capacity (2000mAh) compared to some others, they’re good for 30A continuous draw. Good charge specs too. He sent info in a spreadsheet, with all the cells tested capacities and internal resistances.
This was when I was balancing the groups. I did it in excel and got all the 3P groups really close in capacity (within <8 mAh)
Mocking up the battery. I downloaded this series of cell-holder models from thingiverse: https://www.thingiverse.com/thing:2526936 I modified one of them to support 15 cells, using Autodesk Fusion 360. I then printed 4 of them on the Markforged X7 at the company I work for, CADPRO Systems. They fitted up really nicely.
The drive components turned up in the mail, from BuildKitBoards.com so I mounted them up.
I then got to work building a DIY spot welder with some electrodes I turned on my father’s lathe, as well as some 3D printed components, a motorbike starter solenoid and a car battery. It worked, but the welds were slightly too inconsistent for my liking and I ran scared.
So I ended up buying this on Aliexpress:
The welds were really good, and consistent, so I started assembling the pack. I used a dremel to clean up the ends of the cells, as they had a few remnants of the tabs that were torn off them.
I added some tabs for the balance leads.
I then mocked up the layout of the electronics, and wrapped the pack.
I ended up cutting the heatshrink off, and redoing it with the BMS integrated. I left little flap in the heatshrink on the back of the bms so I can get the multimeter probes in if I ever need to check the individual cell voltages. I also glued in a 1-wire temperature sensor in case I want realtime battery temp monitoring one day. The wires are not hooked up at the moment, but they’re accessible if I need them.
I was super happy with how the pack turned out.
I was going to make the enclosure out of aluminium, but forgot to order the material before the Christmas holiday. In desperation to get riding, I decided to make one out of bamboo, and it’s turned out so nice I think I’ll stick with it, if it lasts. I used my Vertigo M2 CNC router to machine the components. You can see Vertigo’s page here: https://vertigotech.co.nz/
I was worried about the stiffness of the enclosure making the deck rigid, as I wanted a bit of flex. I designed the base of the enclosure to mount to the deck with 2 screws in the center. To give the ends some support, I added screws there too, but I made extra deep counterbores in the bamboo and put springs under the screwheads. This means that as the deck flexes, only the center of the enclosure stays against the deck, and a gap opens up at the ends of the enclosure, as the springs compress. So the enclosure stays flat, but the deck bends. Works great! I was then worried that the screws would work themselves loose… and then I realised that they won’t be able too, because the lid of the enclosure will prevent them from doing so.
And that’s pretty much it. I’m currently varnishing the enclosure, and sealing it as best I can, in case I ride through a puddle at some point.
I’m now working on a new truck hanger design, with integrated motor mount, which I’ll detail in a separate thread.