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Technochicken
04-01-2012, 02:44 PM
I mentioned in x88x's E-motorcycle build thread (http://www.thebestcasescenario.com/forum/showthread.php?t=28930) that I was working on my own small personal EV, so here's my progress so far.

As with many of my projects, I got most of the parts first and then found a project to do with them, rather than designing a project and then getting the parts for it. Here's the background of how I got the parts.

Five or six years ago, my school's robotics team used to do a competition called FIRST. Now, we no longer have the budget to do that competition, which means that we have tonnes of left over parts from the old robots, such as motors, motor controllers, gearboxes, and miscellaneous other parts like bearings and scrap metal. The teacher that is in charge of robotics wanted to clean out his classroom this year, so he let the current members of the team scavenge any parts we wanted from these old robots. So that's how I got most the core components of this EV for free.

The platform of the scooter is based around an old aluminum Royce Union kick scooter I had lying around. It is very similar to Razor style scooters, but with built in front and back suspension.

Here's the scooter I started with:

https://lh3.googleusercontent.com/-QCk9WlEakq0/T3iMF7PTmOI/AAAAAAAAAg4/dnBF41TR1Nw/s720/1.JPG

Here are the new 12.5" wheels. I was originally going to get 10.5" wheels, but I found these epic snowblower tires (http://www.northerntool.com/shop/tools/product_200331371_200331371) that fit the bigger wheels. These tires are what I will use for serious off road/snow.

https://lh5.googleusercontent.com/-EfV1C3875AM/T3iMb4WpqZI/AAAAAAAAAhQ/hMUpdUL34S8/s720/DSCN3992.JPG

And here's the basic layout. Yes, over a foot of clearance may be excessive.

https://lh6.googleusercontent.com/-3-INIr6BllQ/T3iMmlOXr_I/AAAAAAAAAic/vxSm__yLZwU/s720/DSCN3993.JPG

To fit these massive new wheels, I had to completely rebuild the fork and rear suspension assembly. I built the rear wheel assembly out of a 4" x 1/4" aluminum bar I scavenged, some 2" x 1/4" aluminum bar, and some 3/4" U channel. I also bought some 6", 1500 lbs/in shock absorbers meant for mountain bikes.

Here are the two new shocks compared to the old one:

https://lh3.googleusercontent.com/-GNk8FMP86FI/T3iMhRmdM7I/AAAAAAAAAh0/UpVhntZPl1M/s720/DSCN4029.JPG

Here are the swing arm assemblies:

https://lh3.googleusercontent.com/-BenCgEoc2hU/T3iMqN5SLoI/AAAAAAAAAjA/692JmJjb4sc/s720/DSCN4057.JPG

https://lh6.googleusercontent.com/-qq6md6gM36Y/T3iMwbtgxnI/AAAAAAAAAkE/5xF3iTg2LfI/s720/DSCN4070.JPG

Attached to the scooter platform:

https://lh3.googleusercontent.com/-kg26-NCeNnc/T3iMsoBAPqI/AAAAAAAAAjY/Svrmx7Wijdg/s720/DSCN4061.JPG

Here's where the wheel will go:

https://lh4.googleusercontent.com/-EtesU2ziuJI/T3iMtPzLB8I/AAAAAAAAAjk/DC4HllklNYc/s720/DSCN4062.JPG

The fork had to be completely rebuilt as well. I started out by taking apart an old mountain bike fork. I removed the springs and dampers from the legs of the fork, and cut off the legs. In their place, I bolted pieces of 2" x 1/4" aluminum, to create a leading link type suspension. I built new shock absorbers out of steel tubing, steel rod, and the old springs from the mountain bike shocks.

MTB fork on the scooter:

https://lh6.googleusercontent.com/-scqmitMQzsk/T3iMyqQ_2HI/AAAAAAAAAkc/WDTbwedu8LA/s720/DSCN4081.JPG

DIY shock absorbers:

https://lh4.googleusercontent.com/-XJiTn1SWBkc/T3iM46YMTzI/AAAAAAAAAls/8tujHNBeoQ0/s720/DSCN4092.JPG

https://lh5.googleusercontent.com/-bDpCF7qjN5w/T3iM48-5tWI/AAAAAAAAAlQ/FS1QTVJDvDE/s720/DSCN4094.JPG

Fork:

https://lh4.googleusercontent.com/-lCGePHlRLA8/T3iM7cUiEEI/AAAAAAAAAlk/CqoEvD-IL-I/s720/DSCN4100.JPG

https://lh6.googleusercontent.com/-HIqb0CJFAyg/T3iM8oJH_rI/AAAAAAAAAlw/1O63oqhl1_8/s720/DSCN4113.JPG

https://lh3.googleusercontent.com/-8A4nzCryk_M/T3iM9WB9h2I/AAAAAAAAAl4/SJLBJAripH4/s720/DSCN4114.JPG

With a wheel:

https://lh4.googleusercontent.com/-_udQ7lNFuOA/T3iNBfouXxI/AAAAAAAAAms/TScIMusV1J0/s720/DSCN4121.JPG

I cut dropouts for the wheel, so it can be removed easily (I did this on the back as well, but don't have pictures right now):

https://lh5.googleusercontent.com/-tpTe97BarSA/T3iNHKegQpI/AAAAAAAAAn4/D-1ud10MTzs/s720/DSCN4134.JPG

https://lh3.googleusercontent.com/-dZizlzkqprc/T3iNFHc-MpI/AAAAAAAAAnc/73UxeL27NRM/s720/DSCN4131.JPG

To make sure the handling was okay, I pushed it around the driveway a bit:

https://lh4.googleusercontent.com/-3CzcD8fHAhY/T3iNPAWzNiI/AAAAAAAAApQ/Ixx-eDCf0Ow/s512/DSCN4148.JPG

https://lh3.googleusercontent.com/-iKaZia2jxPQ/T3iNMBCqwfI/AAAAAAAAAow/fYkKiuiBkNo/s512/DSCN4144.JPG

As you may be able to tell from the pictures above, I had to bend one side of the rear suspension assembly to get the rear wheel's sprocket to fit. I did this by heating the aluminum with a torch along the bend line while it was clamped in a vice.


Now for the motor assembly. To power this vehicle, I am using 3 2.5" CIM motors, which are the standard for FIRST robotics. At 12V, which is the limit at FIRST, they only put out about 340 watts of mechanical power at their peak, which isn't very much. I'll be running them at a little over 18V, so I'm estimating that I'll get approximately 750 watts out of each motor (1.5x the voltage, 1.5x the current) That means I'll get a total of 3 horsepower. Now, I could buy a cheap brushless motor and get twice that for 1/5 the weight, but then I would have to actually buy the motor along with a motor controller, and from what I've read, hobby brushless motors/esc's are extremely finicky in personal EV applications. For motor controllers, I will be using 3 IFI Victor 884 controllers. Although these are listed as being max 15V 40A controllers, they are in fact underrated. They are identical except for the microcontroller to the older Victor 883 controllers, which are rated at 24V and 60A. So they should be fine at 18V

Since CIM motors are high speed (about 450 rpm/volt), I built a gear reduction out of two gear boxes I scavenged from school. The gearboxes were originally 2 stage, but I removed the second stage, as there will be additional reduction from the chain drive. The original gearboxes were designed to hold 2 motors each, but since I am using 3 motors, I chopped up the gearboxes and spliced them together into a 3 motor 14:50 reduction. I fastened everything together with this stuff called Alumaweld, which is basically a brazing material that works on Aluminum.

Here's the gearbox:

https://lh6.googleusercontent.com/-Quvzx9A558Q/T3iNUrHD_SI/AAAAAAAAAqM/BkjGDBMUesU/s720/DSCN4158.JPG

https://lh3.googleusercontent.com/-CcawrtzJ8pU/T3iNWNriiCI/AAAAAAAAAqo/6fXmHvjPDj8/s720/DSCN4160.JPG

Here is the inside. I still need to buy one more 14 tooth motor gear:

https://lh6.googleusercontent.com/-mLRLZQpRTjU/T3iNfmxH28I/AAAAAAAAArw/OFiUKoGjMVg/s720/DSCN4161.JPG

The whole unit:

https://lh3.googleusercontent.com/-_MRDJTjgD-k/T3iNaMfuK7I/AAAAAAAAArM/gEMWlQQBGu4/s720/DSCN4164.JPG

That's all for now.

x88x
04-01-2012, 07:08 PM
Heheh, nice. :D

A few questions:

What thickness is the aluminum that you are using for the front and rear forks? The motor plate?

I would be a bit concerned about the controllers, just because I am skeptical how well that fan can push the heat away from the transistors/mosfets without a heatsink on them. This is the point of failure I have seen most commonly in people who have used RC motors on small EVs; they try and use an RC ISC, and it can't handle the heat of the continuous load and blows up. I don't know about Victor in particular, but a lot of these manufacturers rate their stuff to a peak current, or an occasional load. So, they might be able to deal with bursts of 100A just fine, but expect to be at 0 load an equal amount of the time. The problem with dropping that into an EV is that they will instead probably not hit the peak very often, but will spend most of the time at something not 0. So a controller rated to 100A in RC applications will fail utterly in a small EV application where it has to deal with 15-20A maybe 80% of the time.
I know you don't want to buy anything, but it might be worth looking into something like the below. Based on the prices I'm seeing, you could probably sell those Victors and more than cover the cost. Going that route, I would connect the motors in series, use one of the below controllers at ~72V, and run with it.
http://kellycontroller.com/kds72100100a24v-72v-mini-brushed-controller-p-396.html
http://kellycontroller.com/kds72200200a24v-72v-mini-brushed-controller-p-288.html

Also, I'm sure you've realized this already, but those tires are going to be incredibly inefficient. Should be fun though. ;)

I look forward to seeing this get moving! :D Any thoughts yet on batteries?

Technochicken
04-01-2012, 08:05 PM
Heheh, nice. :D

A few questions:

What thickness is the aluminum that you are using for the front and rear forks? The motor plate?



Both the forks are made from 1/4" thick aluminum. The plate used for the rear forks is 4" wide, and and the front is 2" wide. It should be way more than strong enough, especially since I weigh under 140 lbs.



I would be a bit concerned about the controllers, just because I am skeptical how well that fan can push the heat away from the transistors/mosfets without a heatsink on them....
http://kellycontroller.com/kds72100100a24v-72v-mini-brushed-controller-p-396.html
http://kellycontroller.com/kds72200200a24v-72v-mini-brushed-controller-p-288.html


I've played around with the idea of using a high voltage controller and wiring the motors in a series, but I think I'm going to at least give the victors a shot. I have six of them in total, so even if I toast one of them, I could probably sell them and get a Kelly. I've seen the Victors used on robots that weigh more than I do, so hopefully they'l handle the abuse.



I look forward to seeing this get moving! :D Any thoughts yet on batteries?

I'm definitely going to use LiPo's, but I'm not sure what configuration yet. It depends on how much space under the platform I end up having after getting the motors and controllers mounted.

TLHarrell
04-01-2012, 11:29 PM
Not sure about the geometry of the front end. Since the wheel is forward of the center of turning, it's likely to want to swivel around 180 degrees (like a caster on a shopping cart). I would at least add some width to the handlebars to help counter that. Still, just looking at it scares me. I had a gas powered one that somebody gave me. Sold it once I got it working. Too much likelihood of eating pavement real hard.

Technochicken
04-02-2012, 08:54 AM
I the low-speed tests I've done, the steering geometry has not been a problem. Because of the kick scooter frame I used, I had to choose between having a decent amount of suspension travel and having the wheel set back closer to the steering axis. For better or worse, I chose more suspension.

nevermind1534
04-02-2012, 10:47 AM
Those CIM motors and gearboxes look familiar.

Technochicken
04-07-2012, 03:26 PM
I've attached the motors and gearbox to the scooter platform using some 1" angle aluminum and my last left over bit of 2" x 1/4" bar.

https://lh6.googleusercontent.com/-_zSpQvYnRu8/T4CNUaZcPXI/AAAAAAAAAsg/73rTcxOxuYA/s1024/DSCN4169.JPG

https://lh5.googleusercontent.com/-C5i4Og3HdAw/T4CNV1RVPgI/AAAAAAAAAs4/k1doQp7MtMU/s1024/DSCN4173.JPG

https://lh3.googleusercontent.com/-K28sEEmmF0E/T4CNWP6mk-I/AAAAAAAAAtA/VS-wbP_VDUM/s1024/DSCN4179.JPG

https://lh6.googleusercontent.com/-mjKJdYJp6k0/T4CNXS3AO2I/AAAAAAAAAtQ/BQKoQSSAt4c/s1024/DSCN4181.JPG

https://lh5.googleusercontent.com/-C_ewwLyflYI/T4CNXjAmvMI/AAAAAAAAAtU/povUlbAM8gw/s1024/DSCN4183.JPG

https://lh6.googleusercontent.com/-qc8nhzJz-KY/T4CNX0H6alI/AAAAAAAAAtk/LGRVIueYj-A/s1024/DSCN4185.JPG

I'm thinking about making a new platform to stand on that is wider then the current one, and just bolts on top. A slightly wider platform should give me enough room underneath to fit 3 5Ah 5s LiPo packs side by side. I could have two rows of three without the batteries extending below the bottom of the gearbox, giving me a 18.5V, 30 Ah battery pack. If I chose to get a single controller to run all three motors in series, I could easily reconfigure the pack to be 55.5V, 10 Ah.

d_stilgar
04-07-2012, 07:56 PM
Cool stuff. I can't wait to see more.

Technochicken
04-14-2012, 08:36 PM
I've pretty much finished the chain routing. Because the drive sprocket is not mounted on the axis of rotation of the rear suspension arm, as the suspension is compressed, the effective chain length is increased. To compensate for this, I built a chain tensioner that can take up the slack in the extra chain required to accommodate the suspension, similar to how a derailleur on a bicycle lengthens or shortens the amount of chain used to allow for different gear ratios. Unlike on a bicycle, where the the chain tensioner pushes the chain outwards, this chain tensioner pulls the chain in, so that the chain does not reduce the clearance under the scooter.

Here is the assembled drivetrain. I still need to borrow a chain tool so that I can remove the extra links and close the loop. The idler sprocket above the tensioner routs the chain under the suspension arm, which it would hit otherwise:

https://lh3.googleusercontent.com/-WS2pjrc2Xoo/T4oSMuXG6rI/AAAAAAAAAuE/qgcILV4lqWs/s720/DSCN4191.JPG

Here is the chain tensioner. I pulled the spring out of an old bicycle derailleur:

https://lh4.googleusercontent.com/-gft5dvDrcEI/T4oSM9dKCwI/AAAAAAAAAt8/zh9bziJ9Fms/s720/DSCN4193.JPG

https://lh6.googleusercontent.com/-qC-76w_Ytr0/T4oSOiqhNrI/AAAAAAAAAuc/hITls5Qa3DM/s720/DSCN4198.JPG

Here is a template I made for the new platform:

https://lh3.googleusercontent.com/-MyF7eC_tq8g/T4oSOu0aGyI/AAAAAAAAAuY/tGNtbccjOEg/s720/DSCN4201.JPG

And here are a couple pictures of the whole thing so far:

https://lh6.googleusercontent.com/-zTIuKmODB7A/T4oWwuYBsHI/AAAAAAAAAus/66v5wuSNhiY/s720/DSCN4207.JPG

https://lh5.googleusercontent.com/-UC2f05ELKxk/T4oWwkXw6nI/AAAAAAAAAuw/ZnuE2EPWKrw/s720/DSCN4209.JPG

The next step is to order batteries, charger, and a few other small electronic bits, and an 1/8" aluminum sheet to make the new deck.

x88x
04-15-2012, 03:05 PM
Nice wrap on that chain layout.

Technochicken
05-09-2012, 01:38 PM
Not sure about the geometry of the front end...

After a lot more thinking about how I could relatively easily change the fork geometry to improve handling, I went for it and rebuilt the fork. Steering feels much better now, and I did not have to sacrifice any suspension travel, because I just increased the clearance.

https://lh4.googleusercontent.com/-3g7m9DooKsg/T6qbEKNFreI/AAAAAAAAAzI/rgl7w6Z2i5c/s512/DSCN5235.JPG

https://lh6.googleusercontent.com/-2jZjaaKwx1k/T6qbECPTR2I/AAAAAAAAAzM/9Rpj2uC4uQk/s512/DSCN5236.JPG

For anyone interested, here are the motor controllers. I think I may go ahead and take x888x's suggestion and try to sell these off to get a proper vehicle controller like a mini Kelly.

https://lh5.googleusercontent.com/-y-HMeTNu1rM/T6qbEEeWGeI/AAAAAAAAAzQ/gy_ZefLmEok/s720/DSCN5237.JPG

https://lh3.googleusercontent.com/-9z4vUiZOZnA/T6qbFDkEp5I/AAAAAAAAAzg/DOJoIXGnVkA/s720/DSCN5239.JPG

Technochicken
05-12-2012, 01:38 PM
I posted the controllers on ebay, if anyone happens to be building a robot, or something else that might need a few big h-bridges. Heck, you could even hook one of these up to an arduino and and all your case fans, and have an absurdly overpowered fan speed controller.

http://www.ebay.com/itm/IFI-Victor-884-Speed-Controller-12-V-40-Amp-/110878289188?pt=LH_DefaultDomain_0&hash=item19d0dc6d24#ht_500wt_1361

TLHarrell
05-12-2012, 08:04 PM
That steering geometry looks a whole lot better now. Now all you need is a good motor driver and you're ready to faceplant with the rest of the kids. I wouldn't ride one unless I was wearing a football helmet and full riot gear.

Technochicken
05-12-2012, 10:15 PM
4 of the Victor motor controllers sold already, which should cover one of these:

http://kellycontroller.com/kds72200e200a24v-72v-mini-brushed-controller-p-762.html

Should be more than enough power, at 120A continuous at 55.5V, 200A peak, and all three motors in series.

TLHarrell
05-13-2012, 12:14 AM
I can't wait to see some video on YouTube of your first ride. It's gonna be epic.

x88x
05-13-2012, 08:43 PM
Heheh, sound good. That should give you a lot more oomh for less $$. I'm actually considering picking up one of those controllers to play around with for my little scooters.

Technochicken
05-23-2012, 11:17 AM
I put in the order to Kelly a few days ago, so I should have the controller and a throttle pretty soon.

All the progress on this so far has been towards getting the scooter to actually move. But an equally important aspect of the build is how, once the scooter gets moving, I will be able to stop it.

The geometry of the wheels I am using does not accommodate the addition of rim brakes, so I decided to use the large sprocket on the back wheel as a disk upon which disk brake calipers could clamp. After all, brake disks really are are large circular pieces of metal bolted to wheels, so using a section of the sprocket that did not have chain around it seemed an ideal place to fit a brake. I had two main problems with this plan. First, as x88x pointed out, due to the chain tensioner I have an absurd amount of chain wrap around the large sprocket. This leaves only one spot where I could fit a brake caliper. Second, no one makes a disk brake caliper that would fit in the available space (or around a sprocket either, for that matter). Here's what I came up with.

Here is the actual caliper. The pads are standard road bike brake pads. The inner (left) pad is fixed to the large "U" shaped block of aluminum, which slides within the bit of U channel aluminum that is bent and screwed to the frame. The right brake pad is connected to the rod that passes through the springs. The two part spring, divided in the middle, ensures that when the brake cable (visible just above the spring) is pulled, both halves of the brake caliper move towards each other, rather than one side being fixed and the other moving. The block of metal all the way on the right, which the cable and sliding rod with the springs pass through, is fixed to the sliding rod via a set screw, so that the rod moves when the cable is pulled.

https://lh6.googleusercontent.com/-6_mked8yRY0/T7z2hS04lOI/AAAAAAAAA0E/XIirQVIwRlo/s1024/DSCN5314.JPG

With the sprocket in place:

https://lh5.googleusercontent.com/-mnBwepmDVM0/T7z2i9vdtFI/AAAAAAAAA0k/JZ9R8dony1Y/s1024/DSCN5316.JPG

https://lh4.googleusercontent.com/-yvrijkn3T3c/T7z2knbZEJI/AAAAAAAAA04/4j5JoWqTn_0/s1024/DSCN5320.JPG

Normally on kick scooters, you brake by pushing down a lever above the back wheel with your foot. The lever rubs against the wheel, slowing the scooter down. I wanted the disk brake to be actuated the same way as normal kick scooter brakes are, so I made a brake pedal out of some U and L aluminum. So that pushing down the pedal would pull the brake cable, I added two pivoting linkages to the pedal. In the picture below, the two fixed pivots are the bottom right and bottom center holes. When the pedal is pushed, the two pivoting linkages that the brake cable housing intersects with are pushed outwards (to the left in the picture).

https://lh6.googleusercontent.com/-XV9VFUclPIA/T7z2kQh0aSI/AAAAAAAAA08/aJWXlsEPgnc/s1024/DSCN5359.JPG

And here is the whole thing assembled:

https://lh5.googleusercontent.com/-znuEA1cAJMU/T7z2oO6IrfI/AAAAAAAAA14/GAVTaMckhyY/s1024/DSCN5369.JPG

https://lh4.googleusercontent.com/-DTS5GtN71gQ/T7z2rtapZvI/AAAAAAAAA2c/wpDoWebFQRE/s720/DSCN5383.JPG

https://lh4.googleusercontent.com/-Q5wl7vR147Q/T7z2s9-4wfI/AAAAAAAAA2o/uLrwdABawlI/s1024/DSCN5384.JPG

Brake lever released:

https://lh5.googleusercontent.com/-TUi38be8XBg/T7z2t2-NrVI/AAAAAAAAA2w/579_IYD4Ntk/s1024/DSCN5385.JPG

Brake lever pushed:

https://lh4.googleusercontent.com/-XVwbvOD1O3M/T7z2uAVb4nI/AAAAAAAAA20/dVUPP6AH3uc/s1024/DSCN5386.JPG

https://lh4.googleusercontent.com/-2a2Ag0OT18M/T7z2wHUzBVI/AAAAAAAAA3E/sLdgZW3HLSQ/s1024/DSCN5388.JPG

x88x
05-23-2012, 11:53 PM
Neat idea. I like it! :up: Just make sure you don't use it with the throttle opened up. ;)

AmEv
05-23-2012, 11:54 PM
^Let's have a challenge: What'll overheat first?
The motors?
Or the brake pad?

x88x
05-24-2012, 12:33 AM
The brake pad.

mDust
05-27-2012, 03:31 PM
Unless the rear axle is somehow a freewheel, I would think trying to spin ~3hp worth of motor would have a pretty large braking effect.

It's a cool project, especially for the budget. I have a huge backlog of projects that I've yet to have the time (all work and no play makes Jack a dull boy.:dead:) to get started, let alone completed. My damn sig is evidence of this...:( I planned an e-bike a while back and reading this just bumped it up closer to the top of the to-do-list.

Thanks for the inspiration!

x88x
05-28-2012, 01:18 AM
I planned an e-bike a while back and reading this just bumped it up closer to the top of the to-do-list.

Hit me up if/when you do decide to take the plunge. Whether electric bicycle or motorcycle I have some good links for you. ;)

Technochicken
05-31-2012, 12:38 PM
The controller arrived, along with a twist grip throttle, a fuse, and a few other small parts.

Next to a DVD for size reference:

https://lh4.googleusercontent.com/-MG8CyoEQWUk/T8eaafqDMZI/AAAAAAAABCA/pXWMBcQyWXw/s1024/DSCN5429.JPG

I replaced the handlebars with the bars and stem from a scrapped mountain bike.

https://lh4.googleusercontent.com/-gfK7TeIs8ZU/T8eaal-68ZI/AAAAAAAABCE/E7_Ol1m4Gok/s720/DSCN5431.JPG

https://lh6.googleusercontent.com/-FZeWKF9ZcJ0/T8eabDkm6UI/AAAAAAAABCU/yET9SzwM0AE/s1024/DSCN5432.JPG

What I've mainly been working on is building a new platform. At first I thought about just buying a sheet of 1/8" aluminum, but I decided to see what I could come up with with materials I had on hand. I realized that I had a large amount of carbon fiber tow left over from the bicycle I built (http://build-its.blogspot.com/2010/09/building-bamboo-bike-frame.html). I built a frame to stretch the tow over, and layer by layer formed it into sheets by soaking it in resin and clamping it between two pieces of plywood. The final sheet has 5 or six layers in each direction. I'm sure the carbon/resin ratio is not the best, but it still is unbelievably strong.

Here's the sheet:

https://lh6.googleusercontent.com/-kv6thchjdiw/T8eaYggQzOI/AAAAAAAABBk/uCmCz1jYvRo/s1024/DSCN5427.JPG

https://lh3.googleusercontent.com/-DLNN8tVSOMw/T8eaYUTSUdI/AAAAAAAABBo/v2_K4CMHy40/s1024/DSCN5426.JPG

Cut to shape:

https://lh6.googleusercontent.com/-6YUxCgWo8nM/T8eaaTN1pxI/AAAAAAAABB8/4kB_DQBofAE/s1024/DSCN5428.JPG

Since CF isn't very abrasion resistant, I cut a top layer for the platform out of a scrap sheet of polycarbonate I had lying around, to stop the CF from wearing down. I cut the polycarbonate platform a little bit wider than the carbon layer, so that the polycarbonate will take any impacts, rather than the carbon. Right now, I'm working in bonding the two layers together. The resin I used on the carbon does not bond well to the polycarbonate. I've found that CA glue bonds the two very well, but I haven't thought of a good way of applying CA over such a large surface area.

Polycarbonate:

https://lh6.googleusercontent.com/-Fvx_fEgmTg8/T8eaYeQN1LI/AAAAAAAABBs/pRCgBFNEjuY/s1024/DSCN5425.JPG

That's all for now. I've ordered a few more parts, like a battery charger and a master power switch, and I'm waiting for the batteries to come back in stock.

mDust
06-02-2012, 09:51 AM
Nice work. Are you going to put some grip tape or something on the polycarbonate? You could also cut some grooves into it if it's thick enough. I imagine it would be pretty slick with a little sand or water on it. I'd hate to see you break bones on the first ride and not be able to ride it again for a month...

x88x
06-02-2012, 07:10 PM
OOC, what charger and cut-off switch?

Technochicken
06-02-2012, 07:45 PM
@mDust:

Shoes seem to have pretty good traction on the polycarbonate, but I'm going to experiment a bit to see if I'll need grip tape.

@x88x:

I had a 25$ gift card to Amazon, so I got a imax b6, which should tide me over until I can get something more powerful.

The switch is a Hella master power switch. It's rated for 100 amps continuous, and a lot more than that for short bursts.

The Turnigy 5S lipos I've been looking at have been out of stock for a while, and I've been thinking about using these 15C Zippy's (http://www.hobbyking.com/hobbyking/store/__16802__ZIPPY_Flightmax_5000mAh_5S1P_15C_USA_Ware house_.html). A pack made from those would be able to put out 150A continuous, which is more than enough, but in your Honda thread you noted that the Turnigy's seem to be better quality than Zippy's, so I may just wait it out.

x88x
06-02-2012, 11:59 PM
The Turnigy 5S lipos I've been looking at have been out of stock for a while

Gee, I don't know why that would have happened.. :whistler:

Fair warning, assuming my finances are in order when they get re-stocked, they will be out of stock again quite shortly thereafter... :whistler:
...need another 100 to finish off the pack...



Something you want to consider with hobbyking lipo is that it is much happier (and safer) if you don't try to push it to it's spec. Particularly with the lower-spec stuff. About half the rated C-rate is the general rule of thumb for max recommended output. So if you're wanting 150A out of the pack, and you build it with 15C cells, I wouldn't go any smaller than a 20Ah pack. If you're only building a small capacity pack, it's definitely worth it to splurge on the nice cells. Any idea what sort of range/runtime you want on this thing?

For the switch, do you know if that 100A is the carry current or the break current?

The imax b6 is a decent entry level charger. It should do what you need. Once you decide on a pack size, if you are expecting to use this regularly at all, you may want to look into a charger that can handle the whole pack at once.

Technochicken
06-03-2012, 09:14 AM
The motors I'm using should pull just under 200A when stalled at full power - which should never happen during use. It should draw well under 50A during typical use, and I'm estimating 20-25A at full speed on flat ground. I'm planning on a 10Ah pack to start out, but I have space under the deck to upgrade it to 15 or maybe even 20 later. The purpose of this vehicle is for tooling around, not actually getting me a long distance, so any battery life above 30 minutes is fine.

I'm not sure about the switch. Here are the specs:

- Continuous rating: 100 amps
- Surge current: up to 1000 amps
- 3/8" copper terminals, silver-plated

http://www.robotmarketplace.com/products/0-SWHELLA1.html

I've seen it used in a number of similarly sized EV builds, so I think it should be alright.

x88x
06-04-2012, 03:32 AM
A few things I would note on the batteries:

1) With 10Ah you're probably not going to get 30m of runtime. Probably looking at more like 15-20m, depending on ride style.

2) I would recommend getting some sort of cell monitor. If nothing else, a cell-log or similar to keep an eye on at least one pack. If you keep them in a healthy range, the rest of the cells shouldn't vary much.

3) Make sure you don't over-discharge the cells. General rule of thumb is to only discharge them to 3.6V and not charge them over ~4.1-4.2V, depending on how careful you want to be. Most lithium chemistries have very distinctive discharge/charge curves, with the majority of the charge lying between two voltage levels, and on either side being what we call the 'cliff'. Basically, above a certain voltage (~4.1V with LiCo), the voltage spikes. And below a certain voltage (~3.6V with LiCo), the voltage drops precipitously. What this means is that if you pass either of those points, it is very easy to over-charge or over-discharge (respectively) the cells. Add in the fact that you get very little benefit from passing either of those points, as those points are at ~90% and ~10% state of charge (SOC), and it's really just not worth the risk. These are great batteries, and can be very safe and dependable (or I wouldn't be using them on my motorcycle), but can also be seriously dangerous if not treated properly.

For more information on these cells, check out this thread.
http://www.endless-sphere.com/forums/viewtopic.php?f=14&t=19956

Technochicken
06-04-2012, 10:23 AM
Over discharging the packs shoudn't be an issue, assuming they all discharge evenly. The Kelly is programable, so I can set a hard low voltage cutoff, and a soft cutoff where it reduces available current.

As far as monitoring voltage, I've been looking at something like this, which could give me the entire pack voltage, so I have a rough idea of how much time I'll have left:

http://www.adafruit.com/products/705

x88x
06-04-2012, 04:09 PM
Problem you'll run into there is that the cells will sag a bit (how much depends on what cells you get and how much current you pull), so they will drop below 3.6V during normal operation, even though they have not yet hit 90%DOD (Depth Of Discharge). You'll want your hard-cutoff at 3.0V, as that should be a last-ditch 'if I keep going on this, I will kill the batteries' cutoff. The soft cutoff I would put at probably 3.5V, as in my testing, my '20C' cells sagged ~0.1V at 40A (8C) draw. That cutoff will ramp back the current it's pulling, to decrease load on the cells, which will in turn raise the cell voltage.

Monitoring the full pack voltage should be fine for normal operation, but I would highly recommend getting a celllog (or something similar) for quickly and easily checking the individual cell voltages afterwards. You want to keep a particularly close eye on them for the first few cycles, and you want to check all pack before hooking them up to anything. Because of HobbyKing's less-than-stellar QC process (hey, they're dirt-cheap and mainly targeted at RC stuff, what do you expect?), expect about 10% of the packs to arrive with at least one cell either DOA (0V), or close to it. Also, if any of the pack you get are puffed at all, don't touch them, immediately file a claim with HobbyKing and carefully properly drain and recycle the cells (do the same for DOA or <2V cells, to be safe).

As a corollary to that, make sure you order ~10% more packs than you actually need.

CellLogs:
http://epbuddy.com/index.php?main_page=product_info&cPath=30_8&products_id=27
http://epbuddy.com/index.php?main_page=product_info&cPath=30_8&products_id=14

Technochicken
06-10-2012, 11:45 PM
These are in stock for the first time in ages:

http://www.hobbyking.com/hobbyking/store/__18631__Turnigy_5000mAh_4S1P_14_8v_20C_hardcase_p ack_USA_Warehouse_.html

I'd be really pushing the voltage limits of these motors, so I might need to set a motor current limit lower than 100% if I used them in a 16s, 10ah configuration. I'm really tempted, as they are the best deal on hobbyking, in terms of watt hours per dollar.

*update*

Well, I went ahead and ordered 9 of those batteries (one extra in case of duds). More mechanical updates to be posted soon.

x88x
06-11-2012, 10:22 PM
Holy crack, they have 1032 in stock! ...I may be getting some myself...just on principle...plus, I'm sure I could find a use for them...yeah... :twisted:

Technochicken
06-17-2012, 08:32 PM
Update time!

First off, I finished the carbon fiber/polycarbonate deck. I found some epoxy designed for plastics, that bonded the two extremely well. I drilled and tapped some holes directly into the old scooter deck, and screwed in the new deck with stainless countersunk hex screws, and installed the master power switch in a convenient location:

https://lh4.googleusercontent.com/--nD6jLpr3dg/T95zbJCVdDI/AAAAAAAABHg/jG6NP1JeXqc/s720/DSCN5503.JPG

https://lh3.googleusercontent.com/-uKELFRU21z8/T95zbairBNI/AAAAAAAABHo/BLcHsXf_yAw/s720/DSCN5504.JPG

To maximize battery space, I mounted the motor controller to the gearbox, via some angle aluminum:

https://lh4.googleusercontent.com/-pSD8QmUGe3Q/T95zY-aKnjI/AAAAAAAABGw/DKzA-uglmC4/s720/DSCN5496.JPG

https://lh5.googleusercontent.com/-RVM_Hv0G3cU/T95zYlcM21I/AAAAAAAABGo/O1oh3HHKwig/s720/DSCN5497.JPG

I wired the motors in series, using some large bullet connectors, and added screw terminal connectors to the first motor's positive and last motor's negative, to connect to the motor controller. I soldered a solid copper spacer to one (salvaged from a heatsink), so that I could connect the terminals parallel to the top of the controller:

https://lh3.googleusercontent.com/-lB9ZRQSBh_Q/T95zYoZGvbI/AAAAAAAABGs/TiBtTDAUmy0/s720/DSCN5498.JPG

https://lh4.googleusercontent.com/-H61Ck1HpZ1c/T95zaPZtX9I/AAAAAAAABHQ/nyvfxdbbw1s/s720/DSCN5501.JPG

https://lh4.googleusercontent.com/-BDKob-qOuQU/T95zacS0iII/AAAAAAAABHY/rzPr8h3-a5Y/s720/DSCN5502.JPG

I made a bracket that bolts to the underside of the platform out of some more angle aluminum, to mount the fuse holder to, as well as route the cables through:

https://lh4.googleusercontent.com/-adgfFfU6NS0/T95zdebssXI/AAAAAAAABIM/5dgPN3ABAm0/s720/DSCN5509.JPG

https://lh4.googleusercontent.com/-OU4MyEZrnvI/T95zfNLNgSI/AAAAAAAABIg/AvKlX6E-y0s/s720/DSCN5512.JPG

https://lh4.googleusercontent.com/-XhXWi1G0vuk/T95zfDrR4qI/AAAAAAAABIk/MoMN6Cti-iE/s720/DSCN5513.JPG

https://lh4.googleusercontent.com/-X4zBcc9GuWs/T95zfbEsYXI/AAAAAAAABIw/9-EEPBLdv6Y/s720/DSCN5514.JPG

While testing the suspension, I previously noticed that the 8mm stainless rod that is the pivot point of the rear swingarm flexes significantly under loads (e.g. me jumping up and down on it). To fix this, I drilled out all the holes to 1/2", and inserted a 1/2" stainless rod scavenged from an old scanner. I also had some 1/2" shaft collars lying around, so I added those to secure it:

https://lh6.googleusercontent.com/-rPjl-bpbD4E/T95zhSTm5KI/AAAAAAAABJE/IaDyRRZ1VeU/s720/DSCN5520.JPG

https://lh4.googleusercontent.com/-OhE74I-rZA4/T95zigrfMLI/AAAAAAAABJQ/ZSyXTrMmdNU/s720/DSCN5521.JPG

That's if for now. The batteries are due to arrive on Tuesday. Then all I need to do is wire up the pack and build an enclosure for it.

Technochicken
06-19-2012, 06:46 PM
Batteries arrived! I ordered one extra, but ended up not having a single dead cell in any of the packs, so I have an extra to mess around with. All the packs came charged to 3.85 volts per cell, +/- .01 V.

https://lh4.googleusercontent.com/-29JCjtcjQDE/T-EAgyYbt-I/AAAAAAAABJ0/BTOzi_Uy51U/s640/DSCN5523.JPG

x88x
06-19-2012, 08:08 PM
I would recommend running them through some heavy charge cycles before using them on the scooter. A car headlight is handy for such things. If you have something to monitor the cell voltage, do so. Cut it off when the first cell reaches 3.6V and see how far apart the cells are. This will help give you an indication of if you have any cells in danger of infant death (ie, puffing/etc after only a few cycles).

Technochicken
06-26-2012, 09:46 PM
Lots of progress to share.

It's rideable! But first...

Batteries: after testing the batteries for duds (thanks for the suggestion x88x), I wired pairs of them in parallel, including the balance connectors:

https://lh4.googleusercontent.com/-OjVrXwaD4hQ/T-o8zqqnvwI/AAAAAAAABLM/ZH59DFrA-1Q/s720/DSCN5531.JPG

https://lh3.googleusercontent.com/-ofEAP2ezCEo/T-o8yMzY4iI/AAAAAAAABKg/rCgaGGeqc_E/s720/DSCN5529.JPG

Next, I worked on a battery case out of angle aluminum. Later on, I will cover the sides with some sort of plastic, like acrylic, but for now most sides are open. Rather than bolting the angle aluminum together, I decided to braze it, with the left over rods I used on the gearbox:

https://lh3.googleusercontent.com/-UO7i6nfD1OM/T-o8zTf7cNI/AAAAAAAABK4/z4hHdlO1oOw/s720/DSCN5530.JPG

https://lh3.googleusercontent.com/-JD-GCSZCmnc/T-o8yBGkZEI/AAAAAAAABKo/tbxy4uk6NYc/s720/DSCN5527.JPG

I made a front panel to cover the wire side out of a scrap of polycarbonate. It is attached by thumbscrews for easy access:

https://lh4.googleusercontent.com/-CVD6ndAlHrg/T-o8zpOf8NI/AAAAAAAABK8/JBWzIu9-k0I/s720/DSCN5532.JPG

https://lh4.googleusercontent.com/-dDJWypqCeH0/T-o81P-ZalI/AAAAAAAABLI/SEvZ5bkQUC4/s720/DSCN5534.JPG

https://lh6.googleusercontent.com/-jSMBD28wmts/T-o82DqX-HI/AAAAAAAABLg/z9TeZZSaj8U/s720/DSCN5535.JPG

https://lh5.googleusercontent.com/-oFC3XIyl_-0/T-o82mp8pWI/AAAAAAAABLo/HId7uof1VW0/s720/DSCN5537.JPG

https://lh5.googleusercontent.com/-suXbnZYrgSc/T-pO8VrBr6I/AAAAAAAABMA/ziicI748W-8/s720/DSCN5553.JPG

Here you go, a compilation of clips from my first test ride. Note: the video stutters at time because my camera fails, not because of your computer/youtube.

KeNypuEwUJc

Summary:
I need a stronger spring on the chain tensioner. When I go over large bumps, it frequently throws the chain.
The brake works great.
Acceleration is great. I have to be really gentle on the throttle to stay on (as demonstrated at the start of the video)
I'm not sure what the top speed is, I would estimate in the mid 20's. It feels fast, and I wouldn't feel safe going much faster than the top speed. I'll do a proper speed test with GPS later.
The motors get quite hot after riding. The motor controller gets warm, and the battery pack doesn't seem to heat at all.

It's a blast to ride, even on roads.

TLHarrell
06-27-2012, 12:00 AM
Looks like fun. I'm not riding it without riot gear and a crash helmet.

x88x
06-27-2012, 12:49 AM
*watches the opening launch*

Heheh, yup, that's about what happened the first time I tried one of my scooters on lipo. :twisted:

About what throttle level are you hitting in the video?

The motors are likely not intended for continuous use, thus the high temperatures. Do you have a temperature probe of some sort that would let you see how hot they get?

Technochicken
06-27-2012, 09:45 AM
For most of the video, I'm barely touching the throttle. The only full throttle bit I caught on video was the very end.

The motors are fine for continuous use...at 12 V. Seems that 20-22V makes them a little unhappy. However, they didn't burn out, which is a good sign, and if they do, they are the cheapest component of the scooter. And no, I don't have a temperature probe. They have ferrite magnets though, so I don't really have to worry about destroying the permanent magnets.

Technochicken
07-05-2012, 09:15 PM
To make the batteries more convenient to charge, I made use of my computer modding skills to build an all in one power supply and charger. I pulled the 12V 18.5A power supply out of a dead iMac I had lying around, and mounted it to a composite sheet. I screwed standoffs into the sheet, to make another layer above the power supply. The charger is held to the layer via some cable management clips that came with a PC case. I then mounted the whole assembly in an old ATX psu shell.

PSU:
https://lh5.googleusercontent.com/-vEXhzKRqsPc/T_Xzk-qAU-I/AAAAAAAABYY/eUeMu-mgzqA/s640/20120629_205932.jpg

Mounted together:
https://lh6.googleusercontent.com/-tCF2leNRxs8/T_XzhSv_32I/AAAAAAAABW4/GpvmwWY6mIg/s640/20120629_205215.jpg

In the case:
https://lh3.googleusercontent.com/-utb7QDQHta8/T_XzjhyrPTI/AAAAAAAABXU/_7v4bECguW0/s640/20120629_205630.jpg

I also made a parallel charging harness, so I can charge all the packs simultaneously.

Also, to prevent the chain from coming off, I built a chain guard out of some angle aluminum. I cut wedges out of it so I could bend it, and then brazed over the seams.
https://lh6.googleusercontent.com/-lBdhTRCUFPU/T_Xy3QCjTVI/AAAAAAAABTA/tRgUle85kzA/s640/20120705_152905%2520-l.jpg

And a video. I made a camera mount out of an old cell phone holster, and it attaches just below the handlebars. It could use some more stabilization.

_6e4MBaeqxo

During this ride, I reached a max speed of 24 mph, and went 15 mph average while moving.

As you'll notice, it didn't go as smoothly as I had hoped. The chain guard did work, and I was able to go over the trail much faster than I had previously been able to. That is, until the chain broke the chain guard:

https://lh6.googleusercontent.com/-xCXiWHK78j8/T_YUDhJdhgI/AAAAAAAABYo/JVRqBT_jZvw/s640/20120705_180122.jpg

I've rebrazed it, but it obviously needs to be supported on both ends. Also, I managed to lose the master link of the chain at the end of the ride, when I went off the large bump between the grass and the asphalt. I ordered 5 more from McMaster, so they should show up in a day or two.

Also, some pictures of the whole thing:

https://lh6.googleusercontent.com/--gsqLfsu9n0/T_Xy8Uaz4HI/AAAAAAAABUM/H406mBMKMKU/s1024/20120705_153932.jpg

https://lh5.googleusercontent.com/-JqytrRTG-qM/T_Xy-d86yHI/AAAAAAAABUk/BfykIh1_zAM/s1024/20120705_154012.jpg

https://lh6.googleusercontent.com/-VJ3rJSnPz0A/T_XzCeC_MFI/AAAAAAAABV8/hNZ2jfCRenk/s1024/20120705_154155.jpg

OvRiDe
07-07-2012, 03:46 PM
Nice work.. and congrats on Hack-a-Day!!

http://hackaday.com/2012/07/07/all-terrain-electric-scooter-build/

Technochicken
07-10-2012, 11:46 PM
Thanks! Here's a third video, same course as last time, but smoother due to a helmet cam rather than one mounted on the frame, and also a bit faster than last time.

8MvDYclN7J0

Looking back this was a terrible idea, but I tried going up a long steep hill at the end, and I gave it full throttle most of the way up. At the very top of the hill, I noticed a huge drop in power, and it sounded like the chain had come loose again. It hadn't, but it still made weird grinding sounds when I turned the throttle. Turns out I burned out two of the three motors. They can still turn, but they do so much more slowly and less smoothly than they should. I opened them up, and one clearly has some burned out windings. The enamel on the wire is blackened in places. Lesson learned. :facepalm:

I have one extra, as does a friend of mine, so it should be back up and running this weekend. Also, I have some more drivetrain refinement to do to keep the chain in place on impacts. Basically, I just need to slightly rearrange the idler sprockets.

mybadomen
07-22-2012, 10:19 PM
Wow incredible work. Lol this might be totally different but seeing it seems you know allot about controllers and Motor you might be able to help me huge.

I have a Golf Cart that seemed to be the same concept. New Batteries New potentiometer however you spell it. Anyway the electric throttle part is new. I cleaned every terminal. Took the Motor apart to check out inside. Brushes all looked good as well as the winding from what i could tell. I cleaned everything inside also. The solenoid tests correctly . According to the test procedure one side should be roughly 5 volts lower then the other or its a bad solenoid. Anyway i tried everything and its been 2 weaks now and im still not sure whats wrong. The controller on your scooter looks exactly like the one in my cart just smaller.

Here is my problem is is driving me crazy and making it so we cant use our cart.

Its a 36 volt Yamaha G16E 1998 golf cart but that shouldnt matter as we are just speaking electronics right now. Batteries fully charged right off the charger are around 40 volts but drop to about 38v and stays there. That's normal. Also i know these Batteries are perfect because they are less then a month old purchased by me and i use them in my old 1986 cart that runs fine with them.The 1998 cart we bought to replace the 86 but since owning it have had no luck.

Ok here is my question that you may be able to answer. I have lets say 38 volts during testing. The cart is extremely slow after driving maybe 20 feet. So i drove it sitting on the floor testing Voltages with the peddle to the floor. Wide open Throttle i get 38+ volts everywhere besides the wire going from the controller to the Motor. That wire only shows 24 Volts? I tested at the Motor which has 4 posts 3 show over 38 volts but the one coming from the control only shows 24 volts.

Your Opinion or anyone else reading this threads Opinion on what is wrong?

Bad Controller? (Everything is aiming to this but i always thought when a controller died it just dies completely. I can still drive around just extremely slow 2mph maybe)

Bad Motor? (Everything looks ok to me but really not sure how to test it with the 4 posts.I know the Motor moves the cart)

Sorry for asking this question but after reading your whole log i realized your Scooter mod is basically same as a Golf cart as far as electronics go.

Awesome ,Awesome talent you have Kid. Also you look young so i can only imagine your future.

Very Impressed !! (Also let me know if you can help me with my problem)

MybadOmen

CorsePerVita
07-24-2012, 04:25 AM
Nice work dude!

I'm curious though, what made you want to use the specific tires you have on it?

Technochicken
07-24-2012, 02:35 PM
Thanks!

I thought about using mountain board wheels at first, but I decided I wanted at least 10 inch wheels, for both clearance and their general ridiculousness. These particular wheels came with a hub that was designed to have a sprocket mounted to it, which was convenient, and also I have the option of switching to knobbier tires, (http://www.northerntool.com/shop/tools/product_200331371_200331371) if I want to try riding in the snow or something like that.

My only real complaint about these wheels is that they have pretty crappy bearings that are poorly shielded and have some play in them. Switching out the bearings is one of the first things I plan on changing when I start school and have access to more tools.

@mybadomen (I totally read your name as "my abdomen" by the way :facepalm:)

Thanks!

It could be that your throttle's output range does not cover the entire throttle input range of the controller, so that the controller never gets the full power signal, even if the throttle is floored. Is there any way you can either adjust the positioning of the throttle's potentiometer, or reprogram the throttle input range of the controller?

If you're sure that it's not the throttle, if the motor's only getting 24 volts from the controller, but you're putting 40 volts into the controller from the battery, that's a lot of voltage drop over the controller. That does make it sound like a controller problem rather than a motor problem.


Back on topic. I've replaced the motors, rebuilt the chain tensioner to accomodate more extra chain, and significantly rearranged the idler sprockets. I'll be doing another test ride this afternoon, to see if it all paid off. Pictures and maybe another video of the changes are on the way.

CorsePerVita
08-04-2012, 09:12 AM
MOAR VIDEO! Lol! This is a rad project man. That is a really cool way to get around. Once you minimize the leeching friction, what do you think the max distance will be?

Technochicken
08-10-2012, 11:02 PM
Well, I lied when I said I'd have pics and a video soon, but I have them now. Since the last post, I've actually gone through two chain tensioner editions, the first of which was a miserable failure, and the second of which is pretty much the final version.

http://2.bp.blogspot.com/-6cI9cdkKEcM/UCWKyVBaD8I/AAAAAAAABkM/Hyw-Ufd9Fac/s640/20120807_193431.jpg

This new tensioner is made from of 1/4" aluminum. I got the metal from some iMac stands I happened to have lying around, which is why the larger surfaces of the metal are anodized.

The bolt that holds the right side of the spring was screwed directly into the 1/4" edge of the aluminum. You can just barely see the peaks of the screw's threads on the side of the metal, since the screw only has about 1/64" of metal on each side.

I would have preferred to have the smaller sprocket at the end of the swinging part of the chain tensioner, as it would respond to bumps more quickly due to it's smaller mass, but the geometry did not work out.

http://3.bp.blogspot.com/-C7TliHbQzA8/UCWKzYz1rDI/AAAAAAAABkU/5zaautrrneU/s640/20120807_193537.jpg

The pivot point actually pivots around a bearing(!). Since I don't have the proper tools for either boring a press fit hole for the bearing or actually pressing the bearing in place, I used the same method I did for the tensioner's small sprocket: I drilled out a 1/2" hole, which is the largest drill bit size I have, and then carefully filed the whole to the 7/8" O.D. of the bearing. I could not apply enough force to press the bearing in place with my wooden vice table, so I carefully hammered the bearing in, with an anvil (yes, I have an anvil but don't have a proper vice) on one side, and a block of aluminum on the other, so that I wouldn't destroy the bearing's shielding.

http://2.bp.blogspot.com/-CjHCl-e_SOo/UCWK1t3FwfI/AAAAAAAABks/w68N5Ib4uH4/s640/20120807_194002.jpg

The combination of actually using bearings and using a lot more metal makes the whole assembly feel extremely solid, especially compared to the previous version. To mount the chain tensioner to the swingarm, I bolted it through two 1.5" x 1.5" squares of 1/4" aluminum. Where it's mounted, there's a full inch of solid aluminum.

I kept the part of the previous chain tensioner assembly that stopped the chain from coming off the drive sprocket, as it did it's job properly.

http://4.bp.blogspot.com/-UZyVe3J8-_o/UCWK3_pPFWI/AAAAAAAABk8/Mb3PQjsOtSk/s640/20120807_194552.jpg

I added an assortment of stickers to the steering column. From top to bottom, the are:

Alot (http://hyperboleandahalf.blogspot.com/2010/04/alot-is-better-than-you-at-everything.html) (is a lot better than you at everything)
Atlanta Mini Maker Faire (http://makerfaireatl.com/)
Arduino (http://www.arduino.cc/)
Arduino
Instructables (http://www.instructables.com/)


http://4.bp.blogspot.com/-W_8hNIy_cKs/UCWK4ugAiBI/AAAAAAAABlE/-WJbYFDdcJQ/s640/20120807_194943.jpg


This chain tensioner was a drastic improvement over the previous one. I managed to ride two lengths of the trail that I had previously never been able to ride all of without losing the chain. However, riding on the field by my old elementary school, the chain tensioner managed to move more than it had been designed to, so it horribly overstretched its spring. When the tensioner stretched past horizontal, the spring became caught on the corner of the tensioner, which is why only about a quarter of the spring was actually ruined. Fortunately, this is an easy problem to fix. All I need to do is cut off and round the corner, so that the chain tensioner can bend farther without ruining the spring. I know that if the entire spring rather than just a short section of it is stretched, the spring can extend plenty far enough to accommodate the extra chain length.

http://2.bp.blogspot.com/-J6aeAmBfzOc/UCWK5e7HLqI/AAAAAAAABlM/QID_-a6iuUE/s640/20120810_174356.jpg

Finally, here's five minutes of me tooling around on the scooter. I attached the camera to the steering column, rather than my helmet, so the video is pretty bumpy, even after a bunch of post filming software stabilization.

LZ20uC8P1Gw

I'm super close to getting this thing reliable on rough terrain. Hopefully I can completely finish it before I leave for school in a week and a half!

mDust
08-11-2012, 11:45 AM
mybadomen: you should post that in your own thread so more people see it if you haven't figured it out yet.

technochicken: awesome work! what is the top speed and range (in distance or time)? Is it as loud as in the video or exaggerated by the camera or editing? Is the majority of the noise caused by the motors or the chain drive?

Technochicken
08-11-2012, 01:13 PM
Thanks! With the current gearing, the top speed is 25 mph. Riding as I do in the videos, with frequent starting and stopping over varied terrain, it will get about 8 miles. Just riding on long stretches of flat road, it would probably get at least 12, but I haven't actually tested that scenario. It is pretty loud, though not quite as loud as it sounds in the video. Pretty much all the noise comes from the gearbox, as the gearbox's housing seems to resonate easily.

Technochicken
09-13-2012, 11:36 AM
It's been a while, and I have a couple small updates. So, I'm a college student now, and taking all sorts of fun general requirements like multivariable calculus, physics 1 mechanics, and intro biology. Despite having a ton of work, I've managed to make make time for the important things in life, like working on my scooter.

To get my scooter to campus, I had my parents UPS it from Atlanta to Cambridge. In a box. All 75 pounds of it.

Unfortunately, the scooter did not survive its journey unscathed. The packaged seemed to confuse the Portland UPS office, and it spent a day going in an out of the city. By the time I got the package, the box was very sad looking. More sadness appeared when I opened the box.

The first casualty was the metal brake cable noodle, which had been completely crushed:

http://1.bp.blogspot.com/-aEdPVFdUtnI/UFH2cUSs7MI/AAAAAAAAB28/mnEEQGHmgVo/s640/20120910_190011.jpg

Also barely visible in the picture above is that the two corners of the rear suspension arm are bent inwards. Somehow UPS managed to bend 1/4" aluminum plate in the shipping process.

The deck of the scooter must have taken some serious knocks during shipping as well, as in two spots the polycarbonate top layer of the deck managed to de-laminate from the carbon fiber bottom layer. Functionally, this doesn't make a difference, but it doesn't look good and can't really be fixed without completely separating the two pieces and re-gluing them. It's a good thing I did make the polycarbonate extend beyond the edges of the carbon fiber, or the carbon fiber would surely have been cracked.

http://1.bp.blogspot.com/-KZz8IrYlOfI/UFH2dUoxM2I/AAAAAAAAB3E/8v9tzLwKRGk/s640/20120910_190046.jpg

I brought the scooter to MITERS (http://miters.mit.edu) to do some repairs:

http://2.bp.blogspot.com/-f5f9W9rojlQ/UFH2ez-P8KI/AAAAAAAAB3M/9puH9_lJX18/s640/20120912_202013.jpg

I replaced the crushed brake noodle:

http://2.bp.blogspot.com/-syX_iaFRSHs/UFH2f8T4rWI/AAAAAAAAB3U/5vM8iDM_HjM/s640/20120912_202021.jpg

In the process of fixing the scooter, I found a few more things that had been damaged. Somehow, the plastic guard and carbon fiber at the front of the deck got huge gouges in them, and the carbon fiber was split at the edge:

http://2.bp.blogspot.com/-KqyuGqQig_I/UFH2gxaQ3YI/AAAAAAAAB3c/wKICWdI4uoc/s640/20120912_212106.jpg


Also, one corner of the battery box was skewed, as can be seen below. I may end up just plating the entire outside of the box in aluminum, to give the batteries a bit more protection.

http://2.bp.blogspot.com/-xhsLE5YNx2U/UFH2h3HAs5I/AAAAAAAAB3k/VFlyea_Ywtk/s640/20120912_212134.jpg

Thats it for now. Sometime in the relatively near future I plan on making fenders for the scooter, so I can ride it in wetter conditions.

TLHarrell
09-13-2012, 12:22 PM
It truly amazes me that they actually are still in business with the way they treat their cargo, and with the prices they charge! Absolutely ridiculous how much damage it sustained. Do be sure to document all that and file a claim with UPS. This is way beyond the driver simply "rolling" your box up to the door... this is absolutely negligent and downright destructive on their part.

mDust
09-16-2012, 11:54 AM
It truly amazes me that they actually are still in business with the way they treat their cargo, and with the prices they charge!

I have no connection to UPS, but I've shipped and received hundreds of parcels through them and have never experienced anything further than the dented corner of a shipping carton. I've never received anything that was broken during shipping. It's likely one less than careful employee or maybe one facility that may be lax on policy. If stuff like this happened all the time, they really wouldn't be in business.

Just due to this scooters weight, how was it packed? Sorting machines used by UPS, FedEx, USPS, DHL, etc all flip packages end over end. They rely on sufficient packing material and methods to avoid damage. Slapping a fragile sticker on the side doesn't change anything. Something this heavy needs special packaging.

Technochicken
09-16-2012, 12:39 PM
Just due to this scooters weight, how was it packed? Sorting machines used by UPS, FedEx, USPS, DHL, etc all flip packages end over end. They rely on sufficient packing material and methods to avoid damage. Slapping a fragile sticker on the side doesn't change anything. Something this heavy needs special packaging.

It was packed in 3 layers of heavy-duty bubble wrap, all in a cardboard box that some furniture had been shipped in. Honestly, it probably should have been packed in a wooden crate, but I still don't think that poor packaging alone explains all the damage that occurred.

mDust
09-16-2012, 01:01 PM
It was packed in 3 layers of heavy-duty bubble wrap, all in a cardboard box that some furniture had been shipped in. Honestly, it probably should have been packed in a wooden crate, but I still don't think that poor packaging alone explains all the damage that occurred.

No, the other part of the equation is the flipping end over end. It's not an inherently gentle process. The typical light package isn't subjected to much (f=ma), but heavy stuff will beat itself up.

Was there any fill? Did you buy any insurance on it? Send some pics in and see if you can get the shipping fee refunded.

Technochicken
09-16-2012, 01:17 PM
The main thing that I don't think was the fault of the packaging was the the gouges to the plastic and carbon fiber in the front. At some point, the package must have hit some hard, sharp corners for that to happen. Nope, no insurance. I may try sending in some pictures, but I've fixed the functional problems already, so anything left is just cosmetic.