Grand debut- The Electric Skateboard

I’ve been working on this project for a couple weeks now, but haven’t mentioned it here- let’s start from the beginning. I was inspired by this post on Jalopnik– I’ve long been interested in leaning vehicles that aren’t bikes. I hadn’t considered the “skateboard steering” approach before. The more I thought about it, the less it seemed like a good idea for a car, what with all kind of funny things about the way it will steer and handle, not to mention road irregularities causing it to steer erratically. Still, though, it’s a way to make a 4 wheeled thing lean through corners without active hydraulics (which always seemed a bit inelegant to me).

Moving along, I decided that building a skateboard-steering car was not a reasonable project for me, but maybe building a maxi-magnum-electric skateboard could be. I already have an electric transaxle that I found in an abandoned and screwed up electric scooter wheelchair, along with its controller and some junk PbA batteries. And thus the plan was hatched.

The concept: mount the transaxle to the frame with a pivot axle at a 45Ëš angle to the ground, with that pivot axle intersecting the wheel axle. Mount another axle in the same way. If you continue the lines made by the pivot axles they will make a right-side up V when the whole assembly is viewed from the side. So, the pivot axles point up and out from the front and back of the vehicle. That’s how it is in skateboards, as well as the BOB car linked above. Build it. Put batteries and motor controller in the frame, drive it, see what happens.

The first step was attaching wheels to the transaxle- the wheelchair wheels were shot long ago and I wanted bigger diameter wheels for more speed. I ordered a set of these wheels from the Surplus Center. I was expecting to be able to unbolt the rim and take the hub/bearing cartridge off, but it turned out it was pressed into the rim. So I popped it onto the lathe and took care of that – then I made wheel hubs to adapt the .750 double-keyed transaxle shafts to the 2.75″ bolt circle on the rims. The hubs are solid aluminum. Thanks to the Laney machine shop program for that. That stock alone is probably worth more than I’ve spent on the whole project so far.

I then did a bunch of planning and working out triangles and measurements for the frame- I made a rough mockup out of wood that gave me some useful insight to the way the clearances would work out for the steering setup. I decided to mostly use 1″x .063″ mild steel square tubing because I already had about 13 ft. of it, picked up another 20 ft at a local steel dealer. There’s some 1″x1″x.125″ angle iron also, and just a bit of 1/4″ plate. So, this morning I set about building it.

A chopsaw is essential. I have an old delta mitre saw outfitted with an abrasive blade.

Starting to take shape.

Even with many parts still missing, you can start to see how this is going to come togetherI made this hardware in the machine shop on Thursday

So, it got dark and I stopped taking photos, but I did infact get the frame welded up and the transaxle assembly completed and attached to the frame. I will need to do some more work to set up the front axle, and get ahold of (make) a front axle- but that’s going to have to wait for next week in the machine shop.

The deal is, it works. It’s going to work. As soon as I get a chance I will take photos (and video!) of the completed axle assembly. It’s actually pretty sweet how it swings back and forth with the tilting of the deck. The delrin bushings pictured above are the key part of that swivel assembly. I’m not sure how well they’ll hold up, I know that skateboard trucks often use ball bearings- but they’ll work for now. The assembly feels tight, secure and smooth in this initial testing.

I’m pretty excited about this project. I could see this vehicle being a pretty good little around-town runnabout. I also designed the frame to be able to accomodate several battery options- you’d get really impressive range with a 24v x 40AH LiFePO4 pack! I’m definitely hopeful and looking forward to giving it a ride to see if it’s something I want to invest further in.