My 10 year old built a 20km/h (12mph) electric go-kart over her holidays (Build Album)

The Finished Go-Kart! Still needs padded seats and a paint, but that will have to wait until Easter.

"No, it's OK Mum. I'll drive today."

My 10 year old daughter wanted to build a go-kart over her summer holidays, which of course led to a couple of new skills; Metal working, welding, a bit more electronics, and some engineering. And of course I'm a crazy dad, so that seemed like a good thing to do.

Now, imaging you're a 10 year old and you want to make a go-kart, and don't know how big it should be. Two options: Look at someone else's plans or, and clearly this is the "easier" option, do a 1:1 scale plan. Scale was based on it being a two person go-kart, which comfortably holds two kids.

Her plan called for 8m of square steel (We used 35mm, 3mm thickness), 8m of 3x3 angle iron (to build a box to cover the dangerous bits, and have somewhere to hold school bags), and some flat steel just in case. A quick visit to a local steel supplier and we're off and running.

Measure once...

Cut once.... Sometimes twice.

Of course, you can't build a go-kart if you can't weld, so some basic welding classes were required.

If you ever need to teach a nervous 10 year old how to weld my top tip; Start with a good safety briefing, and then just jump on in. In this case, I have a MIG welder with flux-core, so it wasn't too difficult for her to get the hang of it. Starting with straight lines, then letters, then T-joints. She won't be doing welds on a nuclear reactor any time soon, but she's good enough for building the odd go-kart.

The base frame. It's now become ~20cm narrower than the original plan called for, but hopefully that won't be an issue. At this point Mum was starting to raise some questions about roll cages and doors, and the like. Sigh.

So it turns out (having never built one of these before) that the design for the steering section didn't work as the wheels didn't have room to turn. So some rapid prototyping (ie. extending the design with chalk on the driveway), and a new solution was created.

Some quick redesign, and we're off..

The new front end...

The parts that are more easily bought; wheels and steering assembly, rear axle and breaks, all from CutPriceRacing.com.au, and an 800W electric motor and speed controller.

Why 800W I hear you ask? We were in the car and there was an interview on the radio with someone who raced an electric go-kart who said "My 2000w motor gets me about 120km/h", after which my daughter says "Dad, I think I only need 1/3 of that power. I don't really want to go faster than 40km/h" (25mph for our American friends).

Well of course not. But then, I'm thinking I also want a go on this and I'm over 100kg, so lets go with more power than we need, and it can me limited in the ESC if needed.

Assembling the axle. Overkill for a kids go-kart I expect, but grown ups will get a ride too, right?

Welding the fame.

Starting to look like a go kart - frame, wheels and steering all in place. A board thrown on it, and up and the driveway was going well. Did I mention the driveway has a bit of a hill?

BRAKES!!!! A shout out to Paul at CutPriceRacing.com.au here. We were having problems getting the breaks to have enough pressure to grab the disk, so I dropped him an email. The next day he called me, walked me through it, and then posted a whole page of shots and videos explaining the process. http://www.cutpriceracing.com.au/store/GUIDE-BKCC02-Cable-Brake-System/ .
*Absolute dead set legend.*

For internet posterity : Not great welds, but great traction. Breaks fitted, and then onto cabelling...

The test run: Motor, battery, speed controller... And the result? Not quite the desired success. We had a sprocket mismatch, and needed a replacement. Called a local firm and a few days later a couple arrived in the mail. The internet is awesome for finding this sort of thing.

The forward/reverse switch need to go somewhere. She had a brief thought about a full dashboard but ended up deciding to add attach it to the steering whee holder where it’s easy to get to.

The wires were then fed through a hole and runs under the kart where it’s held in place with little hooks. A few days into serious use, this broke during a drive, and was replaced by a toggle switch in the base plate.

A safety box over all the moving and electric parts was the best stop. Whilst she’s fine with bandsaws and welding, the table saw is dads domain. Some to cutting done to her specifications (seat back is on a 30 degree angle) and then screwed together.

An enclosure was needed for school bags, so angle iron was cut an welded. A lot of the welding was done up on an assembly table in my workshop which is just big enough to hold the cart. I use it for wood-working, so the tabletop got a little scorched, but some sanding and it was all good.

Mum goes for a test-drive. One of the cells in the Lipo started to have issues, so the batteries were ultimately switched out for 2x12v Deep-Cycle batteries.

First day driving to school, and a wire had come lose. Leatherman out, wire screwed back into place, and off to school they went.