Picture of Electric Longboard Build & Clever CIM Motor Drivetrain
This Instructable documents the improving of a Proline 600 Altered Electric Longboard. It also serves as a useful resource for anyone attempting their own electric skateboard/longboard build. It ALSO serves as documentation for a mini-build: a new drive-train for the ever-so-popular CIM motors, which are often used in FIRST robotics competitions.

Altered/Exkate electric skateboards/longboards are not known for their turning radius (it's HUGE), their weight (the one we used was 48 pounds stock!), nor their performance (1, yes ONE, wheel drive). In fact, about the only thing they are known for is being one of the first companies to produce electric skateboards/longboards. So we decided to make it better. The further we went, the more we realized we could have started with a deck and built up; thus, I will endeavor to make this Instructable useful to both types of builders.

CIM motors have been without a cheap, easy, and compact gear-reduction drive-train since their beginning. Now the wait is over. Read on!

The team was part of MIT's Edgerton Center Summer 2010 Engineering and Design Class, a month-long class where high school students learn and apply real-world engineering skills to various projects.

Note: I'll apologize in advance for any bad quality photos.

Also Note: I am in no way affiliated with any of the companies mentioned in this Instructable.
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GregN111 months ago

Hi this is a great resource! The link to the battery in the instructions does not work looking at the picture of the battery it said it was 15 c I could not find one of those do you think 20 c would work as well?

Your style is unique compared to other people I have read stuff from.Thank you for posting when you have the opportunity, Guess I will just bookmark this page.

Noaharfarf2 years ago
I PMed the author about this question, but just in case you guys have any info about it too; do you guys know if there is a dual-shaft CIM motor available?
I'm not him, but I believe that there is not a two-shaft CIM. CIMs are a very regulated type of motor, as the main market for them is to FRC teams (robotics), one of which I am a member of.
I know they do not allow two-shafted CIMs, therefore, there would be very little market for them. No market means no product made, so I doubt they're made.
There is, however, a Mini-CIM, which is 2/3 the size, and power, but at the same speed, so if you're thinking of making it two-wheel drive, that may work by mounting them back-to-back.
Kinnishian2 years ago
Do you have any new sources for the planetary gearbox? I can't find any good slim planetary gearboxes. The link in your instructable is dead.
DevixLuvic3 years ago
Hey, this instructable looks really great and I'm going to attempt building a skateboard from scratch. However, while gathering the pieces I see that your link to planetary gearboxes is invalid. Do you have a link to a place where I could buy them now?

After a bit of searching, I found this gearbox:


that should work with a CIM.

Any clues whether or not this is the correct one?

Yashichu3 years ago
So I'm interested in building something like this, but using mostly electric scooter parts on a mountain board. The battery I have is hella heavy and I want to be able to carry the board around when I'm indoors on campus. I love the idea of using lighter batteries and just have this one question. The motor is running on 24V, how would I achieve that with the batteries you used, or something similar?
Being a member of a FIRST robotics team, I'm used to working with CIMs all the time. I think there may be an alternative or two if you are worried about weight. In robotics, we also use motors called Banebots or sometimes Fischer-Price motors. either one of those, combined with the right gearbox ratio, may be a lighter and cheaper option compared to the CIM.

Nice job though!
zenolijo4 years ago
I've started build a electric longboard based on this instructable but from scratch, making a acrylic transparent deck and without the altered electrics module because its so expensive.

I got a huge problem, how does the brake work?
Can't really see any pictures on any physical brake, so i've started thinking that it got to bve the motor.
The only way i find this possible is that the electronics module runs the motor backwards to make it brake, but that feels a little strange.

Can anyone check how the brakes are set up on any altered or other electric longboard?
And what timing belt gear?
If im not wrong, was it this one?
all1by (author)  zenolijo4 years ago
The Exkate controller features regenerative (electric) braking. You could alternatively buy a Kelly controller with regen (or one of a bunch of other brushed motor controllers), if you don't want to spend the hundreds of $ on the exkate controller.

Almost all electric (commercial) longboards use regenerative braking.

I honestly don't remember which timing belt gear I used, but it was similar to that. I suggest experimenting with gear (timing) ratios to find one you like best.

Good luck!
zenolijo all1by4 years ago
Thank you very much!
I'll read some about the kelly controllers :)
nuttyjr4 years ago
Friggin great example of what first robotics kids do after 6 weeks off builld lol
cschultz-14 years ago
What i don't understand, is that your battery system is set up for 36V, but your motors are clearly 12V, and trust me they will burn if you run them at 36??
all1by (author)  cschultz-14 years ago
They are wired in series (36/2=18V), and they can handle 18V without issue.
motleypixel4 years ago
Okay this is cool...I have all the tools including a mini metal lathe etc. I want to build from scratch (ground up) and your instructable isn't 100% detailed. For instance, could you please update some line items like #2 "Two CIM motors", where, how much, part numbers, etc.? What are the part numbers for every "major" component like in #6 the belt gears, you just give the main site and they have a ton of gears? Thanks!
all1by (author)  motleypixel4 years ago
The CIM motors are the classic FIRST robotics motors. I put links in various places in the instructable to their specs. As for a place to buy them, I just googled "first cim motor". Many places sell them. Ex: http://www.trossenrobotics.com/store/p/5142-FIRST-CIM-Motor.aspx

The timing belt gear ratio you use is somewhat dependent on the motor controller(s) you use. If you use the Exkate one like us, then you could try the gear ratio we used. Step 6 mentions the gears we used (44T). https://sdp-si.com/eStore/ , and look under "timing belt pulleys".

Anything else?

Hope that helped.
all1by (author) 4 years ago
Some updates:

1. Make sure you make the bracket-claps better than we did. They should match the profile of the trucks. If they don't, they are prone to slipping. Also, I'd suggest using bigger and coarser thread screws for the clamp. Or just braze or weld it.

2. Make sure you use a good bottoming tap with the drive gear - planetary interface because you'll need as much thread engagement as possible to prevent the motor's torque from ripping the screws out. If worst comes to worse, JB Weld the screws in.
paperclip325 years ago
Great instructable,but I somewhat disagree with the premise of making an electric longboard.I think longboarding is about the experience,about pushing yourself(literally) to go that extra mile.An electric longboard just takes out the fun of riding a longboard,because you're pretty much capped at the speed of the motor,and pushing isn't an option because of the weight. But that's just my opinion.
It is ideal for a person like me who has limited control of my left side due to nerve damage. I felt like a schmuck when I could no longer skate, but an electric drive board put me back on the streets.
Woah.What happened?Are you better now?
all1by (author)  paperclip325 years ago
Have you ever ridden an electric longboard? It's a lot of fun, and I believe it is actually a progression towards the original goal of longboarding: surfing on land. And this board is even more so. But that is just my opinion. As for the speed (if 15mph, 20mph with gear changes, isn't fast enough), the speed of the motor is not the limit- the motor itself is. You are by no means limited to CIM motors. There are hundreds of more powerful (in terms of rpm and torque) motors out there, including much more efficient and powerful brushless motors....the brushed CIM motors are just the tip of the iceberg. With a few hundred dollars in upgrades, I know I could change its topseed to well over 30. However, you are correct about pushing; while it is possible to push this board, it really isn't pleasant.
I know a shop by the beach that rents them.Will try them out sometime! As for surfing on land,I'll have to agree with you.That's where the sport started,am i right?
all1by (author)  paperclip325 years ago
Yep. Just a warning, the boards they rent might not turn well (if the stock exkate we used was any indication).
I tried it out today,you were right about it not turning well. It was pretty cool,but the longboard I rented was topped at 5mph since it was a beachside park with tons of people.
ArNe_4 years ago
(No REPLY button??)

No sensorless.
Making your own sensored speed controller won't be eazy and will take mutch more time. + a more expensive motor :)
I don't think it need to be sensored with that power (can be wrong,, ...will see... ) :)

I measure the current of the motor to adjust the controll signal,, its not really the same as sensored control but better than nothing :)

You need more speed but I need more torque :)

For more speed you need better motors. If you use more motors you will have more torque but still the same speed. (II think you already know that) :)

No problem :) I have the same controller as him to drive my revo (http://www.traxxas.com/products/promo/5605_promo.htm)
Massive brushless power!!!! :D Top speed 65mph! :p
all1by (author)  ArNe_4 years ago
I'm not sure why the reply button disappeared.

I'm running sensored brushless on mine (not the board in this instructable). Like you said, it takes more time and more expensive motors. The reasons for using sensored control are: a. the motors are current (and therefore torque) controlled, allowing for precise acceleration control. b. no cogging because the sensors know what state the motor is in. With sensorless, you might find that you have to kick start the board. As for measuring motor current, I don't see how that could help you control the board if you're using sensorless control. Sensorless control is always voltage control, which means control via RPM and not torque. Another way of putting it is that if you slam on the throttle with a voltage controlled system, it will apply infinite (well, as much as the batteries or motor controller can handle) current until that throttle command (RPM) is reached. There is no direct control of current, so you don't have any direct control over acceleration (indirectly, you do control acceleration by slowly applying throttle so you don't burn out). Sensor vs. sensorless brushless control is a subject I strongly suggest reading up on if it interests you.

I feel "better" is the wrong word, especially because I custom engineered (design and fabrication) them. For more speed, I'd need a motor with one or more of the following: less turns, shorter, weaker magnets, larger diameter tires. However, I felt around 25mph was plenty, so I designed for that.

It is true that if I use more motors, and don't divide the current among the motors, then I will have more torque.

Nice. I used to have a brushless Revo, too. It was an old Gorillamaxx conversion with a Neo 8XL and BK-electronics controller: 1800W. It could hit about 55mph. I sold it because I got sick of replacing twisted Ti driveshafts and shreaded hardened steel diff gears, haha.
ArNe_ all1by4 years ago
I use pwm control so the motor has always the same voltage,, and the same torque
Much better than voltage control.

Do you have pictures or videos of your other boards? :)
I'm really interested :)

I have steed drive shafts on it now :)
I don't have much time for it now...
But I see it on the bright side,, no more broken parts :p
all1by (author)  ArNe_4 years ago
Yeah. There's a link to my blog in the instructable (and from there you can link to other blogs that are amazing sources of knowledge).
ArNe_5 years ago
If you take a total of 9S lipo battery's you have 33.3V and not 36V
all1by (author)  ArNe_5 years ago
You didn't read everything. At full charge, a lipo cell is at 4.2V. At full discharge, it's at about 3V per cell (depending on your LVD or motor controller). Therefore, at max charge, 9S is 4.2*9 = 37.8V. At full discharge, 9S is 3*9 = 27V. Please actually read up on batteries before commenting.
ArNe_ all1by5 years ago
The original batteries are 13,8V when totally charged. 13,8*3 = 41,4V. When using 10S lipo,, at max charge you have 4,2*10= 42V So you do have a little more power and still 30V when full discharged. I use 6 5SLipo's,, 18,5V 5200mah so you have with 10S3P ~37V and 15,8A (for larger runtimes) Its only a suggestion. Its a nice instructable. Do you have a video of it when driving?
all1by (author)  ArNe_5 years ago
We didn't go with 10S because we were worried about over-volting the electronics module and frying it...but that's a good point about the lead acids. Still, we erred on the side of caution, and there is no noticeable speed loss, probably due to the CIM motors. That's a lot of battery. 6.6Ah is plenty for this boards purposes (getting around campus). The other board I'm building will have a 12S setup with either 10Ah or 15Ah. For vids, see the link in step 10.
ArNe_ all1by5 years ago
I'm using 1 big 1KW motor. (35A) So I need the 15Ah :) nice vids You already now the top speed? :)
all1by (author)  ArNe_5 years ago
Dang, what's you're top speed and acceleration like? Our top speed is around 15mph. The other one I'm building will be using four 500W hub motors and it should have a top speed of just under 30.
ArNe_ all1by4 years ago
Its not finished jet :)
I'm building my own speed controller for it.
And I also use a mountainboard wit air tires
Top speed will be (at least) 40 Km/h (25 mph)

If you go faster it becomes a little dangerous...
But it's possible :p

I'll post a video when finished and tested :)

4 500W motors? I think you can reach the 40 mph with that :p
See this link: http://www.hobbycity.com/hobbycity/forum/forum_posts.asp?TID=12064

The board with 4 motors is so awesome!! :p
all1by (author)  ArNe_4 years ago
Are you using sensored control?

For my board, I calculated the top speed to be just under 30mph. My wheels are 4" in diameter compared to the 8" for air tires, so for a given power rating, my top speed will be lower (however, my acceleration can be quicker).

THAT IS AWESOME! Haha, wow. Thanks for sharing the link! He's using sensor-less control, so he gets cogging at start up. I like his design though. Very simple and relatively easy to implement. My hub motor design takes a lot of machining and wouldn't be able to handle the kind of shock loads a mountainboard experiences.
all1by (author)  all1by4 years ago
Oh, and after reading more of the thread, it turns out he switched to sensored control (by just adding sensors to sensorless motors...very easy to do) and his performance improved greatly.
Rimwulf4 years ago
I bought one from Exkate when they were still small, and I found out how expensive they were. See I bought it from my local Spencers for about $39 because it was their last one in stock and had it for years. So it got cheaper but the battery was existed from sitting so long unused. Then I made the mistake of returning it it was only after I found how much it was worth. The only thing I didn't (don't) like about it (them) is that it uses a radio transmitter, I'd prefer wired because there is no chance of someone being on the same frequency. But one question: Doesn't the belt and reduction wheel look a little to close to the ground for turning?
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