|Campus Rider MK I.5| Weld-free Electric Long Board

Lightweight / Folding / Portable EVs - seats optional
lpbug   10 W

10 W
Posts: 66
Joined: Oct 10 2013 6:25pm

|Campus Rider MK I.5| Weld-free Electric Long Board

Post by lpbug » Nov 05 2013 1:33am

Campus Rider: DIY modular electric long board MK I.5

Current MK I.5 Board:
Image
Image

*You may have to zoom out (hold down ctrl and - to zoom out, ctrl and + to zoom back in) to see the pictures fully*

Hey everyone, I've been itching to build an electric skateboard for a while since I got to college but there just seemed to be so little time and resource for the build to make it feasible. However, after finding this forum and getting help from many experienced DIYers and gaining access to the MIT machine shop, I realized that it is entirely possible for me to complete this project. All comments and inputs are welcome, as I am a beginner to EBs. So without further ado, let's get building.

Goals:
1. Build a light electric vehicle that can get me from point A to point B, using ideas and components that may or may not yet have been proven in other builds

2. Document this build and make it as comprehensive as possible so anyone reading this can build a working electric board from scratch (or as close to scratch as possible...)

3. Open-source all CAD parts designed after testing for open modification and improvements

MK I.5 CAD file release here (consistent riding around campus for about 4 months, more than 250 miles with little maitenance) *NOTE*: the hub drives are made to fit perfectly in thick core wheels, see discussion on page 4. Additionally, drawings are in metric so if things look ridiculously big, scale down by 25.4.


*Outdated* MK I CAD file release (successful testing of consistent riding around campus for ~3 weeks)

- 44 tooth Pulley and Truck Mount download here (A standalone copy of just the truck mount is provided on the bottom, but these two can be machined out of the same 3/8'' thick aluminum. The truck mount is designed to be a tight fit- as all Caliber truck cross sectional dimensions are subject to a small but noticeable tolerance- file/sand this down as needed for a perfect fit)

- Hub stop download here (Machine out of 3/8'' aluminum, you can also use thicker stock if you have the means to machine it)

- Outside retainer download here (Machine out of 1/8'' aluminum)

-Inside retainer download here (Machine out of 1/8'' aluminum)

- Motor Mount download here (Make this part out of 1/4'' aluminum, you can use 3/8'' from the truck mount's aluminum sheet if you don't want to buy 1/4'' sheet)

- Truck Mount individual download here (Make this part out of 3/8'' aluminum. I recommend milling the slot by 1/4'' but it's up to you whether or not you want the slot at all.)

4. Eventually miniaturize the whole board down to fit something as small as an Arbor Pocket Rocket

This was what the MK I board looked like in the very beginning lol.
Image
Last edited by lpbug on Mar 23 2014 8:29am, edited 34 times in total.

lpbug   10 W

10 W
Posts: 66
Joined: Oct 10 2013 6:25pm

Re: The Noob's Electric Long Board Build Log

Post by lpbug » Nov 05 2013 1:34am

Checklist of what I have done/still need to do:
- [x] Determine the method with which to mount the motor
Welded mounts are kind of a hassle and are permanent, so I've been shying away from that since a modular solution would be more flexible in the long run for upgrades. Needless to say, when I discovered Caliber trucks (thanks to APS) I was more than ecstatic since for it has surprisingly regular geometry compared to all the trucks out there. The only downside I can see is that the smallest size they come in is in 9'', so fitting it on a small board may prove to be troublesome. Additionally, it may slip.

- [x] CAD the motor mounts and determine belt length to use
I used the belt length calculator on SDP-SI, which offers pitch length (I’m actually not sure what that means) as well as tooth count, given the pulley sizes and center distance. It is a very friendly interface and I just matched the closest numbered tooth belt I could find to yield me the desired center distance.

- [x] Make a complete list of on-board electronics and gather them (future upgrades include a 'smart' arduino controlled board)
-1/8 Scalre Truck Sensored/Seonsorless Brushless ESC 150A *make sure the voltage rating is appropriate with the lipo pack you’re using. I forgot to check this and ended up ordering another ESC that only works up to 4s*
-6s 5000 mAh Turnigy Lipo
-To be expanded

- [x] Gather/make all the parts for mechanical power transmission
[x] 44 groves Wheel pulley (CAD is done, waiting for a time slot on the water jet machine)
[x] 12 groves motor pulley/pinion
-This one was tricky, as I couldn’t find any 12 tooth pulley with the appropriate bore diameter (8mm, I keep finding 6mm) so I ordered a 6mm one and bored it out to 8mm with a lathe at MIT’s Hobby Shop.

[x] Pulley stop/retainer (CAD is done, waiting for a time slot on the Water Jet)

[x] Mounting hardware (screws, nuts, etc)

[x] HTD 5mm timing belt 9mm wide 72 tooth

- [x] Assemble the pieces and test ride

*Note this is not an exhaustive list, and will only be completed once the first prototype is complete.
Last edited by lpbug on Nov 12 2013 1:16am, edited 9 times in total.

lpbug   10 W

10 W
Posts: 66
Joined: Oct 10 2013 6:25pm

Re: The Noob's Electric Long Board Build Log

Post by lpbug » Nov 05 2013 1:34am

Machining: This section documents the parts that I have machined and the method through which I machined the parts. All the parts I used will be open-sourced after sufficient testing, and if you have access to a basic machine shop/ have a "CNC friend" you can replicate this build.

Day 1: Machining take 1
First time using the water jet, probably more excited than I should have been. Parts came out pretty well, but the 48 tooth pulley was just way too big. Also, the truck mount that I had machined had too big a mounting hole, had to go back to the CAD and retry. Either way, here are some build pictures.

Before Water Jetting
Image

After Water Jetting
Image

Pulley (I love that finish)
Image

Truck Mount (Truck extrusion is too big)
Image


Day 2:Getting there (almost)

Skipped classes to use the water jet to cut out another, smaller pulley (added some holes close to the edges for possible flange support, made center extrusion greater to alleviate some unnecessary weight (6061 feels quite strong according to my hand test :lol: ). The Truck Mount was re-water jetted as well. Additionally, I bored out the 6mm 12 tooth pulley that I got from SDP/SI

Smaller, 44 tooth pulley
Image

It gives more clearance from the ground compared to the wider diameter 48 tooth pulley
Image

Truck Mount (required some filing, but I generally had the dimensions correct. I suspect scaling up by 1-2% should do the trick).
Image

Boring out hole for 6mm 12 tooth motor pulley (the bore wall thickness now seems a bit thin, I guess I always have the 17 tooth if this doesn't work.
Image
Last edited by lpbug on Mar 04 2014 2:01am, edited 3 times in total.

User avatar
daverobson08   100 W

100 W
Posts: 115
Joined: Sep 27 2013 8:07am
Location: Blackpool, United Kingdom

Re: The Noob's Electric Long Board Build Log

Post by daverobson08 » Nov 05 2013 3:57am

This build is looking good mate, keep it up! Some nice machining there too

Murfix   100 W

100 W
Posts: 153
Joined: Apr 24 2013 6:51am
Location: Belgium

Re: The Noob's Electric Long Board Build Log

Post by Murfix » Nov 05 2013 4:04am

Holy crap, I'd love to have access to such a machine shop!

Nice work :)
Memo to myself: Screw it, just do it!
1 Apr 2013 - Start pre-engineering my first EV build!
6 Aug 2013 - Ordered all parts for my Emtb 8s 2x2kW 270kv Alien ESC setup.
3 Sept 2013 - All parts have arrived: on to the build!
23 Sept 2013 - First test ride: AWESOME!
7 Feb 2014 - Upgrade finished: 3kW motors, 12S Alien ESC, entire new drivetrain and LED's!
Build topic: http://endless-sphere.com/forums/viewto ... 35&t=52390

torqueboards   100 MW

100 MW
Posts: 2940
Joined: May 27 2013 10:02pm
Location: San Francisco, CA
Contact:

Re: The Noob's Electric Long Board Build Log

Post by torqueboards » Nov 05 2013 8:46am

Awesome work. I definitely like the mount + pulley. Pulley is nice and simple. Interested to see the outcome. 44T is about the most we can go for the size of our wheels. 48T would be way to big. keep up the good work!
DIYElectricSkateboard.com Electric Skateboard Kits

lpbug   10 W

10 W
Posts: 66
Joined: Oct 10 2013 6:25pm

Re: The Noob's Electric Long Board Build Log

Post by lpbug » Nov 10 2013 6:20pm

Day 3:

Milling out the slot for motor mount
Image

Finished product. A little iffy on the finish but it'll work.
Image

Water-jetted motor mount
Image

Apparatus put together
Image

Closeup front
Image

Closeup back
Image

lpbug   10 W

10 W
Posts: 66
Joined: Oct 10 2013 6:25pm

Re: The Noob's Electric Long Board Build Log

Post by lpbug » Nov 10 2013 6:56pm

So I have actually finished the build, put it all together, soldered up the electronics, and tested the board. IT WAS AWESOME. Out of my excitement, I taped all the electronics down on my board (pictures to come lololol) only to forget to secure the JST-XH to the board. I stopped to inspect the board and I saw these scintillating sparks coming right off the battery pack. Well, it turns out that the JST-XH plug had ripped off (I'm assuming it was because I rolled over it with my wheel or it caught on something) and that the leads were shorting with each other- two of them even welded together. Surprisingly, the battery pack is still fine and I will be looking into repairing it sometimes soon.

torqueboards   100 MW

100 MW
Posts: 2940
Joined: May 27 2013 10:02pm
Location: San Francisco, CA
Contact:

Re: The Noob's Electric Long Board Build Log

Post by torqueboards » Nov 10 2013 7:11pm

Amazing build. Would you be willing to sell the drive wheel cog. I assume you have bolts that secure the drive wheel cog can you show more photos?

would you also sell the caliber mount?
DIYElectricSkateboard.com Electric Skateboard Kits

lpbug   10 W

10 W
Posts: 66
Joined: Oct 10 2013 6:25pm

Re: The Noob's Electric Long Board Build Log

Post by lpbug » Nov 11 2013 11:54pm

At the moment, I have no plans to commercialize the kit. Instead, I will release the design (DXF CAD) files for free when the first prototype has been thoroughly tested at which point you could have a machine shop machine the part. Universities are also a good place to find undergrad mechanical engineers who will be more than willing to machine the part for a small fee.

Thanks for the interest though!

User avatar
kkEdlund   1 W

1 W
Posts: 50
Joined: Oct 05 2013 2:57am
Location: Salt Lake City, UT

Re: The Noob's Electric Long Board Build Log

Post by kkEdlund » Nov 12 2013 9:08pm

How did you deal with the taper when you cut your timing pulleys on the waterjet? Waterjet cutters (especially lower-pressure ones) tend to leave a "beveled" edge as a consequence of a bunch of factors (tiny variations in the size of the abrasive particles, materiel thickness, cut speed, etc...). Really fancy 5-axis machines can angle the nozzle such that the taper is moved into the scrap (where it does not matter) and the finish edge is left straight, but from the pic your waterjet looks like a regular 2-axis setup.

For lots of stuff this taper is not a serious problem, but I would suspect a timing pulley with teeth that are not co-radial across their width would have a tendency to eat belts. Have you ridden your board enough to notice if this is a problem?

torqueboards   100 MW

100 MW
Posts: 2940
Joined: May 27 2013 10:02pm
Location: San Francisco, CA
Contact:

Re: The Noob's Electric Long Board Build Log

Post by torqueboards » Nov 12 2013 9:20pm

I definitely like those pulley wheels and want to make a pair myself. Seems like a cost effective solution waterjetting it. Shouldn't be too much since aluminum itself is fairly cheap.
DIYElectricSkateboard.com Electric Skateboard Kits

User avatar
kkEdlund   1 W

1 W
Posts: 50
Joined: Oct 05 2013 2:57am
Location: Salt Lake City, UT

Re: The Noob's Electric Long Board Build Log

Post by kkEdlund » Nov 12 2013 9:49pm

I've been meaning to try and waterjet a set of pulleys for awhile (since I started looking for parts for my first build in October), but I'm not sure how they will turn out. I should have time in the next couple weeks or so to find out, but I'm not convinced they will be comparable to pulleys cut in a hobbing machine, or even a live-tool lathe.

lpbug   10 W

10 W
Posts: 66
Joined: Oct 10 2013 6:25pm

Re: The Noob's Electric Long Board Build Log

Post by lpbug » Nov 13 2013 2:22am

The taper is almost negligible even for the 3/8 in aluminum pulley. I was able to choose cut quality from 1 to 5 and went with 3 to save time. As you could probably guess, the higher the quality, the longer it takes but the less taper it will have. Personally, I think there will be more misalignments in other parts in a DIY build and that the taper really makes no significant difference. I have ridden a total of 10 miles on my board so far with no problems. Also it should be mentioned that I did not add flanges to the pulley- which was what I was going to do if the belt gave me any issues. Everything has been working great so far.

torqueboards   100 MW

100 MW
Posts: 2940
Joined: May 27 2013 10:02pm
Location: San Francisco, CA
Contact:

Re: The Noob's Electric Long Board Build Log

Post by torqueboards » Nov 13 2013 2:42am

Awesome. Could you show more photos of the entire board + pulley and wheel?
DIYElectricSkateboard.com Electric Skateboard Kits

lpbug   10 W

10 W
Posts: 66
Joined: Oct 10 2013 6:25pm

Re: The Noob's Electric Long Board Build Log

Post by lpbug » Nov 16 2013 11:23pm

Torqueboards:

The apparatus is pretty much set up as follows...

three nuts->hub retainer->hub stop (plug-like pieces you see in the pictures)->pulley->three nuts

all with threaded rods going through.

Hub stop
Image

Hub retainer with nuts
Image

torqueboards   100 MW

100 MW
Posts: 2940
Joined: May 27 2013 10:02pm
Location: San Francisco, CA
Contact:

Re: The Noob's Electric Long Board Build Log

Post by torqueboards » Nov 17 2013 1:30am

Awesome, is the hub stop or shaft that goes inside the wheel simply for adding more strength for the bolts to pull with? Instead of it trying to move the wheel w/ just the bolts alone?

How's your 1 motor 6S setup coming along? Does it climb hills pretty well?

I noticed there is no keyway in your motor pulley that is attached to the motor? Is it only being held onto the motor shaft by set screws? How well is it working for you?
DIYElectricSkateboard.com Electric Skateboard Kits

lpbug   10 W

10 W
Posts: 66
Joined: Oct 10 2013 6:25pm

Re: The Noob's Electric Long Board Build Log

Post by lpbug » Nov 17 2013 10:00pm

torqueboards wrote:Awesome, is the hub stop or shaft that goes inside the wheel simply for adding more strength for the bolts to pull with? Instead of it trying to move the wheel w/ just the bolts alone?

How's your 1 motor 6S setup coming along? Does it climb hills pretty well?

I noticed there is no keyway in your motor pulley that is attached to the motor? Is it only being held onto the motor shaft by set screws? How well is it working for you?
Yes, the hub stop goes inside the wheel since the main stress will come from the rotational forces and they actually do a fantastic job in preventing the threaded rods from bending. Additionally, the hub stop solution is simple and can be easily machined by anyone who has access to a water jet or CNC mill.

My 6s setup has been ridden around for a week now (mostly to classes) on rough and smooth surfaces. There is not that much hill climbing but I climbed some decent 35-40 degree hills with no problem. I was scared of going too fast but it could definitely handle more. The motor gets ever so slightly warm if I try really hard to feel it, and remains cold with 4s.

The no keyway is no problem. I actually am only using 1 set screw and flat spot to secure the pulley on the shaft, haven't gotten to putting locktite on there yet either now that I think about it! I am 170 lb, and have done some substantial riding, so I am going to guess that the set screw and flat spot is working pretty well.

User avatar
PracticalProjects   10 W

10 W
Posts: 95
Joined: Aug 04 2013 3:47pm
Location: UK
Contact:

Re: The Noob's Electric Long Board Build Log

Post by PracticalProjects » Nov 20 2013 4:53pm

Nice job with the machining! Nice to see another doing it from scratch :D Looks great so far, good luck with the rest of the build.

User avatar
kkEdlund   1 W

1 W
Posts: 50
Joined: Oct 05 2013 2:57am
Location: Salt Lake City, UT

Re: The Noob's Electric Long Board Build Log

Post by kkEdlund » Nov 21 2013 2:05am

lpbug wrote:
torqueboards wrote:Awesome, is the hub stop or shaft that goes inside the wheel simply for adding more strength for the bolts to pull with? Instead of it trying to move the wheel w/ just the bolts alone?

How's your 1 motor 6S setup coming along? Does it climb hills pretty well?

I noticed there is no keyway in your motor pulley that is attached to the motor? Is it only being held onto the motor shaft by set screws? How well is it working for you?
Yes, the hub stop goes inside the wheel since the main stress will come from the rotational forces and they actually do a fantastic job in preventing the threaded rods from bending. Additionally, the hub stop solution is simple and can be easily machined by anyone who has access to a water jet or CNC mill.

My 6s setup has been ridden around for a week now (mostly to classes) on rough and smooth surfaces. There is not that much hill climbing but I climbed some decent 35-40 degree hills with no problem. I was scared of going too fast but it could definitely handle more. The motor gets ever so slightly warm if I try really hard to feel it, and remains cold with 4s.

The no keyway is no problem. I actually am only using 1 set screw and flat spot to secure the pulley on the shaft, haven't gotten to putting locktite on there yet either now that I think about it! I am 170 lb, and have done some substantial riding, so I am going to guess that the set screw and flat spot is working pretty well.
I have 3 setscrews/flatspots on my drive pulley and motor, and blue loctite was not enough to keep them in place. Red seems to be working better, but I still carry a small allan key with me just in case. And I've needed it more times than I care to admit. But, I ride ~30 miles per week and it is all aggressive up and downhill riding with heavy braking (motor bearings are cheaper than shoes, and according to campus police sliding (if I had the skill) in crowds is apparently not an option :? .

I have 2 hills that last 3-5 feet at a 25-30 percent grade, and I lose traction trying to go up them under power and simply flatspot my drive wheel while trying to avoid people on cell phones going down. I need to carry speed and coast up and just ride down with no throttle input or I lose traction. I know you are studying engineering and know what 40 degrees is, but here is a graphical representation all the same:

Image

Also, Fargo Street in LA is a 33% grade. Apparantly there are nutcases who go ride their bikes up and down it:

Image

I think my board maxes out around a 10-15% grade. But I only have 6S, so I don't know what a better power system would be able to do. If you can climb 40 degree inclines, I'd like to know what wheels/motor/esc you have. I'm kind of new to skateboards, but my build is nowhere close to that powerful and even with 90mm, 75A ABEC 11 Flywheels has nowhere near that level of grip.

By the way, props on the hub stop. That is a much simpler solution to what Alien Drive has done. I assume you leave a tab on the piece connecting it to your stock when you waterjet it, so you don't lose the part into the tank?

torqueboards   100 MW

100 MW
Posts: 2940
Joined: May 27 2013 10:02pm
Location: San Francisco, CA
Contact:

Re: The Noob's Electric Long Board Build Log

Post by torqueboards » Nov 21 2013 2:40am

Yeah, I remember previously I was thinking I climbed 30-40% degree hills lol. However, It's probably around 20-25% as 40% is pretty steep.
DIYElectricSkateboard.com Electric Skateboard Kits

lpbug   10 W

10 W
Posts: 66
Joined: Oct 10 2013 6:25pm

Re: The Noob's Electric Long Board Build Log

Post by lpbug » Nov 21 2013 11:31am

Sorry, I will go out and try to work out a better estimation for the angle of the hill I climbed. You're right- it seems closer to the 33 degree hill shown in the picture rather than 40. These numbers were just products of my eyeballing, which admittedly is probably not the most accurate. It is still a substantial hill in my opinion.

Regarding my power setup- I am running 150A ESCs from Hobbyking, 83 mm ABEC 11 clones, 6s lipo, as well as a 6354 motor.

To be honest, I tried to leave a holding tab but apparently didn't do it big enough so they fell in the tank and I found some unwanted cut marks when I recovered the pieces. They weren't bad enough to actually mess with the structural integrity of the hub stops so I am still using them. I am surprised that the 3 bolts can handle so much torque. But future hill climbing models can feature all 6 hubs to handle even more. Using bigger bolts is also always an option.

Right now, however, I am pretty satisfied with the mechanical aspects of the build- I am currently working on an enclosure for the electronics as well as miniaturization.

torqueboards   100 MW

100 MW
Posts: 2940
Joined: May 27 2013 10:02pm
Location: San Francisco, CA
Contact:

Re: The Noob's Electric Long Board Build Log

Post by torqueboards » Nov 21 2013 2:58pm

lpbug wrote:Sorry, I will go out and try to work out a better estimation for the angle of the hill I climbed. You're right- it seems closer to the 33 degree hill shown in the picture rather than 40. These numbers were just products of my eyeballing, which admittedly is probably not the most accurate. It is still a substantial hill in my opinion.

Regarding my power setup- I am running 150A ESCs from Hobbyking, 83 mm ABEC 11 clones, 6s lipo, as well as a 6354 motor.

To be honest, I tried to leave a holding tab but apparently didn't do it big enough so they fell in the tank and I found some unwanted cut marks when I recovered the pieces. They weren't bad enough to actually mess with the structural integrity of the hub stops so I am still using them. I am surprised that the 3 bolts can handle so much torque. But future hill climbing models can feature all 6 hubs to handle even more. Using bigger bolts is also always an option.

Right now, however, I am pretty satisfied with the mechanical aspects of the build- I am currently working on an enclosure for the electronics as well as miniaturization.
Yeah, great idea with your pulley it's awesome. I'm going to try a few plastic pulleys and just drill through and use M6 bolts probably 6 total and use lock nuts. See how those work and last. I'm working on a waterjet pulley as well and will try it with M6 Bolts. The M6 bolts are a perfect tight fit. I'm hoping they last.
DIYElectricSkateboard.com Electric Skateboard Kits

lpbug   10 W

10 W
Posts: 66
Joined: Oct 10 2013 6:25pm

Re: The Noob's Electric Long Board Build Log

Post by lpbug » Nov 21 2013 3:13pm

torqueboards wrote:
lpbug wrote:Sorry, I will go out and try to work out a better estimation for the angle of the hill I climbed. You're right- it seems closer to the 33 degree hill shown in the picture rather than 40. These numbers were just products of my eyeballing, which admittedly is probably not the most accurate. It is still a substantial hill in my opinion.

Regarding my power setup- I am running 150A ESCs from Hobbyking, 83 mm ABEC 11 clones, 6s lipo, as well as a 6354 motor.

To be honest, I tried to leave a holding tab but apparently didn't do it big enough so they fell in the tank and I found some unwanted cut marks when I recovered the pieces. They weren't bad enough to actually mess with the structural integrity of the hub stops so I am still using them. I am surprised that the 3 bolts can handle so much torque. But future hill climbing models can feature all 6 hubs to handle even more. Using bigger bolts is also always an option.

Right now, however, I am pretty satisfied with the mechanical aspects of the build- I am currently working on an enclosure for the electronics as well as miniaturization.
Yeah, great idea with your pulley it's awesome. I'm going to try a few plastic pulleys and just drill through and use M6 bolts probably 6 total and use lock nuts. See how those work and last. I'm working on a waterjet pulley as well and will try it with M6 Bolts. The M6 bolts are a perfect tight fit. I'm hoping they last.
Huh, interesting- M6 fits perfectly? I might use 6-32 screws for more strength.

torqueboards   100 MW

100 MW
Posts: 2940
Joined: May 27 2013 10:02pm
Location: San Francisco, CA
Contact:

Re: The Noob's Electric Long Board Build Log

Post by torqueboards » Nov 21 2013 3:43pm

Yup. Try an m6 bolt fits right through on one of the insert holes. Tight fit but should be good for the torque. M5 would move inside the insert.

BTW what do you plan on using for your electronics cover?
DIYElectricSkateboard.com Electric Skateboard Kits

Post Reply