Introduction: DIY 3D Printed Electric Skateboard With 1500W of Power!
I saw these videos on the internet with people riding electric skateboard and going really fast. Well, I wanted to do the same thing, but those boards were 1500 USD, too expensive for me. My diy version only cost me 150$ that is 10% of the cost of the commercial ones! Granted mine is not perfect, it easily gets the job done.
Currently I get around 10 km of range at 20km/h, but the range can be easily upgraded by purchasing an additional battery and wiring it in series.
The hardest part of creating an electric skateboard is mounting the motors to the trucks (axles). Other people have achieved this using metal brackets that are welded. I don't have access to a welder so I used off the shelf components, and 3D printed a motor mount to safely and easily mount the motor. I also 3D printed the gears that deliver power from the motor to the wheels. Initially, reliability may be a concern with 3D printed parts, yet, they are very strong and can be easily re-printed and hot swapped at a very low cost. I have not had to reprint any parts as they have not worn in any way. They are truly spectacular in terms of strength.
I could have added Bluetooth phone control but that would not have been practical. Controlling a touch based slider provides no haptic feedback, unlike a car remote, and it is dangerous to keep looking at the phone screen for speed control while riding the skateboard. Plus if you fall, you could destroy your phone.
My Parts (I explain them in more detail in the next step)-
Skateboard- any generic skateboard or longboard that you are willing to convert into an electric vehicle.
For more information on how I built my electric skateboard click on the next step.
Step 1: Choosing Your Electronics
As you saw in the previous part, I had listed the parts that you would need. There is of course some wiggle room in the exact parts that you pick, but only do so if you know what you are doing.
The motor: This should be a big motor around 50 mm in diameter. The KV rating should be under 300 kv. The kv rating denotes the revolutions the motor completes per volt applied. Lower KV motors mean that you get more torque for the same voltage. The only disadvantage to these are that they get really expensive real fast. Therefore an easy way to get a cheap motor and a lot of torque is to use timing belts and to step down the motor revolutions. Some of you may feel like one motor will cause the board to feel unbalanced as their is power only on one wheel. However this causes no difference in life based on experience. You can also look at the big e-skateboard makers such as Boosted boards and see that they too have one powered wheel setups with no issues.
The ESC: based on the motor that you pick, get an esc that can provide 10-20 percent more current than the motor's max current draw. For example if your motor draws 100 Amps at it's peak, then purchase a 110-120 amp Esc. Make sure that the ESC that you pick has a BEC built in. A BEC is a power supply/regulator to power you receiver. This means DON'T buy an Opto Esc, they don't have a BEC and then you need a separate battery or external BEC for your receiver. If you know how to use an external BEC, then don't keep an Opto ESC out of your options.
The batteries- The higher cell battery you buy, the faster you can go. This is irrespective of the torque. As in a 3 cell battery will have the same torque as a 6 cell battery but the 3 cell can only go half as fast as the 6 cell. The 6 cell will be a larger sized battery though. Make sure the esc you have can support the cell count of your battery. A good rule of thumb is to pick close to the maximum cell count that your esc can support. This will allow you to maximize your speed and keep current draw to a minimum. This in turn will keep you ESC cooler than at a lower voltage and higher current.
Step 2: 3D Printed Power Delivery System
From a hardware perspective, you will have to purchase 2 sets of parts. One set for mounting the motor and the other for transmitting power from your motor to your wheels. In this step I will show you how to chose your hardware for the power delivery system.
First you will have to decide how you want to deliver power to your wheels. There are 2 common ways of doing this. The most popular way of doing this is via timing belts and timing pulleys. Think of the kind used in moving 3D printer's axis. This method is relatively inexpensive and you can 3d print the pulleys yourself. The alternative is to use chains and sprockets, the kind used in bicycles. Sprockets are much harder to source and the prices of them are much higher, but they could be more durable than a belt in the long run. Personally I have not had an issue with the belt system yet.
I went with the belt power delivery system. Depending on the motor you choose, you may need to step down the speed but increase the torque. You should aim for a torque level equivalent of a 80 -100 kv motor(If you are around 60-70 kilos the 100 kv is enough. If you are heavier, aim for 80). The formula to calculate your gear reduction ration will be (motor kv / 80 or 100). Since I weigh 60 kilos and I had a 330 kv motor, I used a gear reduction of 3.5. This means, for every 3.5 times the motor turns, the wheel turns one revolution.
Now to actually picking your hardware. Based on the shaft of you motor, pick the number of teeth that you pulley will have. Based on the gear reduction ration, the pulley on the wheels will be the gear reduction value * number of teeth on motor pulley. In my case, the motor has 10 teeth and the wheel has 35 teeth.
Armed with this information, you will have to choose your belt. I chose a HTD-5 belt as it has wider spacing's between teeth than most other belts and this helps prevent against the belt slipping. It also prevents wear in the long run.
Now go to This Website - http://sdp-si.com/estore/centerdistancedesigner/
That website up there would help you choose the exact number of teeth based on the distance from the wheels center to the motor's center. Based on the number of teeth that you calculated earlier.
I purchased my 48 tooth belt through Taobao which resulted in a belt costing about 5$ plush shipping. The website above also (sdp-si) also sells these belts, but they cost between 15-20$. The Chinese belts from Taobao were great and I have no complains having ridden them for many km.
Step 3: Mounting the Motor
This was the most complex, yet creative part of the build. Here is where most skateboards differ, and mine is very unique in this regard. That is because my motor mount is 3D printed with my 350$ Prusa I3 3D printer.
The easiest way to explain my method would be by using pictures. As you can see above, I used generic off the shelf metal pieces and bolted them to the truck with M5 bolts. Then I used a small piece of plywood and attached it to the other side of the trucks to prevent backlash
I went through 3 revisions over 2 months to perfect this. Although this may look flimsy, it is not. I have ridden ~15 km on it and it has not show any signs of wear and tear. It is very firm and rigid due to the anti backlash wooden plate. The best part is that you can easily recreate the motor mount parts if they ever fail.
Please use lock nuts or thread lock to secure all of your bolts. If not, they will become loose and fail.
My 3D printed mount was designed in Autodesk Fusion 360 and I will attach the .stl for it and the Fusion 360 file for you to modify. Feel free to use it and share it, but please credit this Instructable for the idea.
The motor came with a 4 pronged metal adapter (see the images above). This attachment is bolted to the motor, which is then bolted to the motor mount.
Lastly, some of you may be wondering whether you should make the skateboard front or rear wheel drive. I tried both and I did not notice a difference. I personally prefer rear wheel drive as the electronics enclosure protects the motor from airborne gravel and dust.
Step 4: Attaching the Gear to the Wheel
There are 2 ways to do this.
Method 1: Drilling holes in your wheels. I used the Bigfoot Mountain cruiser 78 mm wheels here This is the method I used. Although this may be considered cringe worthy, it really isn't. As long as you drill slow and have accurate markings on your wheel, you will get a good result. I used a 5 mm drill bit and M4 bolts to secure the gear on to the wheel. By using a slightly smaller bolts than the hole, I was able to compensate for any imperfections/human errors in the drilling process.
Method 2:This method involves buying wheels with sections pre-cut. Some options are the ABEC 11 Flywheels or the Orangutan Kegels. Next you would slip bolts thorugh the cutouts and mount your pulleys that way. Unfortunately, these wheels were too expensive so I chose the other alternative.
By the way, the very popular boosted boards also drill into their wheels and those are one of the most popular electric long boards.
Step 5: Mounting the Electronics
There is a lot of play in how you mount your electronics. You could either 3D print an enclosure or make an enclosure. I had some spare pieces of black poly-carbonate lying around so I used them to make the enclosure. I 3D printed a hinge and used multiple Velcro straps to keep the lid closed. I cut the poly carbonate in a simple box form factor and used simple 3D printed 90 degree brackets to hold the enclosure together. Lastly, I used some more 3D printed 90 degree brackets to mount the enclosure to the skateboard.
You could alternatively not build an enclosure for the electronics but that would mean that you could get them wet, dirty and even damage them with gravel picked you as you ride. Li-Po batteries are extremely sensitive to these knocks and without an enclosure you could damage these batteries while riding and this could result in a flaming skateboard.
Therefore, invest the time and build an enclosure around your electronics. It also makes the board look a lot neater.
Step 6: Arduino Battery and Speed Indicator + Headlights
I added a small 10 segment led bar graph in the front of my skateboard to make it more functional and also look cooler. On the side of my electronic's enclosure I added 2 switches. One controls the headlights and the other switches the bar-graph between a speed reading and a voltage reading from the battery. All of this was controlled by an Arduino.
To add additional IO on my Arduino I used a shift register and this easy to sue library found here.
1: The Speed- First of all, my code is available for download on the bottom of this page. To measure my speed, I rode my skateboard at full speed and measure my speed with a phone using GPS. Next I measured my pwm at full speed and at neutral speed. Then I segmented the pwm value into 10 sections and wrote code for the Arduino to read the pwm value from the receiver and display the appropriate speed at the led bar graph in front.
2: The battery level- I took the voltage of a single LI-PO cell from the battery and had the Arduino read it. Based on the voltage it read, I would estimate the battery capacity remaining and display that on the led bar-graph. For a more accurate result you could use a watt-meter, but this was accurate enough for a general understanding of the battery level as you ride. To calculate the capacity remaining based on voltage, I used the chart attached in the images above.
3: Head lights- These are a simple 4 x 3v leds wired in series to accept 12 volts. These 12 volts are supplied by the LI-PO batteries' balance connector.
Step 7: Converting to a Long Board to Eradicate Speed Wobbles.
After some riding, the board would start to sway slightly at high speeds. Keep in mind that I was using a skateboard made for tricks and not a long board made for cursing. A long board does not sway in the same manner due to a greater distance between the 2 wheels (a.k.a wheelbase).
To fix this issue, I drilled additional holes and mounted the wheels further apart from one another. This made my skateboard into a 'ghetto' long board. Online this is known as a 'shlongboard'. And you can check out other people's builds on making them.
After my mod, all speed wobble/sway was eliminated and the ride was much nicer.
Step 8: Riding Instructions
Although my skateboard can start from a dead stop and go to full speed without cogging, I still find it easier to kick start it. The reason for this is that my, and almost anyone's, inertia is too high.Therefore, it is somewhat hard to maintain balance if you start from a stop using only the electric motor.
Once you are riding, keep an eye out for any obstacles and don't look straight down on the ground. Instead look ahead and it will be easier to ride. For brakes, you could either stop by gently lowering your foot on to the ground, or use the electronic brake functionality found on the ESC.
Step 9: Additional Advice and Further Improvement Ideas
Next time I think I will directly go to a long board rather than a modified skateboard to be more like a long board.
I would also like to implement a better carrying solution for when I am not riding it, right now I hold it by the trucks and it works fine, but the trucks do get a bit dusty, so a padded handle somewhere would be more comfortable.
Lastly, I would upgrade my batteries to larger capacity as I can only ride for about 6-7 kilometers at once.
Ride safely and put humans safety ahead of your skateboard's safety.
That's about it really. If you guys have any questions or concerns, drop them in the comments below and I will address them as soon as I can.
I was inspired by this build, so check it out.
Thanks for reading and good luck building your own.