Introduction: 3D Printed Electric Longboard V2
This is my second version of my 3d printed electric long board. You can find the first version here.
I saw these videos on the internet with people riding electric skateboard and going really fast. The practical applications of these boards as a means of transport caught my attention. Not to mention,they looked really fun. Naturally, I wanted one, but those boards were 1500 USD, too expensive for me. Being a maker, I decided to make my own diy version for only about 300$: that is 20% of the cost of the commercial ones!
Currently I get around 10-15 km of range at 25km/h.
The hardest part of creating an electric skateboard is mounting the motors to the trucThks (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. Additionally, I 3D printed the gears that deliver power from the motor to the wheels, the electronic's enclosure, the battery's enclosure, angled risers for better turning etc.
Upon first thought, 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 out 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 on a phone provides no haptic feedback, unlike a car remote. Additionally, it is dangerous to keep looking at the phone screen for speed control while riding the skateboard. Lastly, if you fall, or your finger slips off the phone, you could destroy your phone plus your board and Injure yourself and others.
Step 1: Improvements in This Iteration
Although my first attempt was successful, it had a few major flaws that I wanted to address with this iteration.
The major problems I wanted to address were:
1. Comfort level + usability tweaks
2. Battery life
4. Aesthetics and the finished quality of the board
Here is a short summary of how I addressed these problems
Comfort- I Switched to a proper Long board made for cruising rather than a skateboard made for tricks.
Usability tweaks- I redid the whole power management in the board making it super easy to monitor battery status, charge the board, and turn it on or off very quickly.
Battery life- I switched to a much larger 4000mah 6S battery. I also upgraded to a much more efficient ESC for longer range
Safety/ reliability- I used a much improved mounting solution which I shall talk more about further in the Instructable
Aesthetics + Finished quality- the electronics were hidden in a much better manner. The cable management is a lot neater and weaker materials such as wood have been substituted for fiber glass or 3D printed plastics.
This is just a short summary of the tweaks I made. I will discuss these in further detail in the next few Steps.
Step 2: Parts+ Electronics
Esc (these components send power to the motors)
Long board- any generic long board would work
There is 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 3: 3D Printed Power Delivery From the Motor to the Wheel
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 4: 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 DIY 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 Fiberglass 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 plate. In this iteration I also added another backlash system that uses a ball bearing mounted to the other side of the motor to further prevent the motor from flexing. The best part is that you can easily recreate the motor mount parts if they ever fail since they are all 3d printed. 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.
I also added 3D printed 15 degree angled risers to the trucks for a smaller turning radius
Step 5: 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 6: 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 decided to 3d print one since I was using many 3D printed parts for this build. I 3D modeled the enclosure in Auto desk 123D and 3d printed it. i added a XT-60 connector on the side of the board for power in. This way the battery can be easily unplugged for charging.I used a large push button to connect the battery to the esc. This button additionally activates the receiver and the battery monitor.
For the battery, I used 3 mm thick plywood to create a door for the battery. As you can see this door slides in and out of the battery compartment and allows you to easily remove the battery without removing any screws.
Due to the way the electronics are contained, you don't need to remove the battery to charge it. You can just disconnect it from the electronics compartment and connect it to the charger
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 7: Riding Instrucitons
Although my long board 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.
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Please be positive and constructive.