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Making my own mobility scooters
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Picture of ToddAllen
Location: Chicago, IL
Registered: 01-18-2008
Posts: 88
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A couple years ago my wife and I decided to commit to staying in our house and put in an elevator. Our house is small and we struggled to cram in as large an elevator cab as possible, ending up with one just 42" long by 33" wide. After searching the internet for mobility scooters and not finding anything appealing that would fit in our elevator I decided to take a go at building my own.

Mobility scooters have a step through design with ones legs in between the seat and the front wheel. Which tends to make them too long to fit in our elevator. To achieve a smaller footprint I decided to try a step over design with my legs straddling the front wheel. I sit on the seat from one side and once seated lift my leg over the handlebars to straddle the scooter.

I built my first scooter very quickly starting with a mountain bike left out for garbage pickup in our alley. I hacksawed the frame and welded it back together to accommodate a 16" front wheel with a bicycle hub motor. I used a pair of 10" pneumatic wheels for a garden cart on the rear. I made a deck from a discarded table and put a bucket on it for a seat. It worked out so well I was soon riding it everywhere including to my neurologists office, 30 miles round trip.

I had only intended to ride it around the house and yard and it didn't hold up well as I kept boosting the speed and riding it further and harder. Frequent repairs kept it rolling until I got my second scooter built intended for street riding longer distances at higher speeds. Bucket scooter 2 was better and faster but still suffered limitations of being built from recycled materials. And changes to make it more road worthy made it less nimble in our house.

Which inspired me to join a local hackerspace and learn machining. I've attached a picture of bucket scooter 3 which I made from scratch at the hackerspace using high quality materials such as 4130 cromoly steel purchased from Wick's Aircraft Supply to build a strong but light frame which I fitted with components sought out to build a high performance scoot.

It's a joy to ride around the house and yard but also rides very well on Chicago streets at 30 mph. Top speed is currently a little over 40 mph and it goes over 40 miles on a charge. Yet, it's small and light enough that my 5'3" wife can carry it by the original plastic bucket handle and set it in the back seat of her compact hatchback car.

bucket scooter 3
Picture of Bruce
Registered: 09-28-2005
Posts: 631
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Todd, thanks for sharing. Innovative, serves the purpose intended, probably a lot of fun to design, and a lot of work to build and modify. Good job!
Registered: 10-22-2005
Posts: 124
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Cool! What are the specs on the motor, controller, and battery?
Picture of ToddAllen
Location: Chicago, IL
Registered: 01-18-2008
Posts: 88
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quote:
Originally posted by Cam:
Cool! What are the specs on the motor, controller, and battery?


Cam, specs are slippery but I'll try.

The pictured motor is an 8 lb geared brushless DC hubmotor for bicycles. It's called a MAC motor and would be rated 1000 watts but I bought it from a place that caters to DIYers and offers performance customisations. Mine has an upgraded stator with thinner low loss laminations and an armature with low turn count windings of thicker wire. The motor also has doubled phase leads. The stock motor is intended for use in a 26" wheel but I laced it into a 16" rim. These mods improve efficiency at speed and I can run it at up to double the rated voltage without meltdown.

Theoretically the performance could be 4000+ watts, but this motor's performance is primarily limited by it's internal gears. It's a planetary reduction with steel sun and annular gears sandwiching 3 plastic planet gears. The plastic gears make it smooth and quiet but they limit the max torque the motor can develop. And at high rpm they suffer accelerated wear which results in a lowering of the peak torque to failure.

The gears are replaceable and by fragging a couple sets I have some sense of the limits. The gears are most prone to abrupt failure with motor stalled while developing large torque such as when trying to power up over a curb or steps from a dead stop. This can happen perhaps as low as 1500 watts. At speed the gears will handle higher power levels. I've run 3000 watts through it at speed without obvious harm. However extended high power/speed accelerates wear and leads to a later low speed high torque failure.

I've run the scooter with this motor for 10's of miles at 40+ mph but then sheared the tips of gear teeth in low speed high torque conditions they would have previously survived.

Pushing it hard helped evaluate frame design but I've currently configured it to run about 1650 watts peak power and 30 mph top speed.

On the previous frame I was able to run higher peak wattage because the wheel base was shorter and the more lightly loaded front wheel would more readily spin out or pop over obstacles limiting the stall torque. But the larger wheel base of this frame improves handling on rough surfaces and at speed.

The controller is rated for a peak of 40 amps at 100 volts, digitally programmable to lower levels. I've run it at 40 amps and at 100 volts but not at the same time with this motor.

I'm currently using lipo battery packs made for radio controlled airplanes. The scooter goes ok on a single 6 cell (~24 volt) 5 ah pack which weighs about 1 lb for a range of about 8 miles at ~12 mph. If I'm going out with my wife in her car with the scooter then this is how I load and run it.

For independent travel at high speeds and long distances I'll use bigger batteries made from many of the small RC packs wired in parallel and then in series. I've used as many as 24 lbs of batteries which can give 50+ miles at 25-30 mph. The scooter could easily carry twice as much battery, perhaps three times as much but the batteries cost $40-$50 a lb and it's rare that I want to travel farther than 50 miles without recharging. And by slowing to 15-20 mph I can squeeze out quite a bit more range in a pinch.

I'm contemplating another build and although higher performance is tempting I'm currently leaning towards building a smaller, lighter lower performance scoot for travel with my wife.
Registered: 10-22-2005
Posts: 124
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You've done a lot of work there. I had been looking for outdoor mobility and found the ranger: Lyric Ranger The company, however, is not very responsive to inquiries. If I had your talents, I'd make my own, too.
Picture of ToddAllen
Location: Chicago, IL
Registered: 01-18-2008
Posts: 88
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Cam, thanks for posting the link to that scooter. I hadn't seen it before and it's the closest I've seen to what I'm doing using the same type of motor and very similarly sized wheels. I imagine there are going to be more scooters of this style as hub motors have become extremely popular for electric bikes and there are plenty of choices appropriate for scooters.

As for building scooters, it's more about circumstance than talent.

I was pretty certain I had this disease as a teenager. But I wanted to believe that if I stayed active I could stay fit and avoid ending up dependent on a mobility scooter like my grandfather.

I used to run for fitness thinking if I just kept at it I'd always be able to run. When my ankles started giving me too much trouble I switched to bicycling and thought eventually I'd slow down but I couldn't really imagine ever giving up cycling. And as I started to slow down I experimented with electric assist systems thinking they could keep me biking until the end.

When I started getting neck and wrist pain on conventional bikes I started riding recumbents. Eventually transitioned to recumbent trikes.

After we put in the elevator I started reconsidering mobility scooters but failed to find anything I liked that could fit in the elevator. During my bicycling days I discovered Chicago's large and diverse bicycle culture/community and was exposed to a lot of creative bicycle hacking where people chop and weld junk bicycles into tandems, recumbents, choppers, freakbikes, tallbikes, etc.

Which led me to experiment with a chop and weld mobility scooter. And then another.

So I got where I am today mostly by a long series of unrealistic expectations. Pretty much at every step on the way I've made mistakes. I suppose my talent is learning from mistakes because I provided myself lots of learning opportunities.


quote:
Originally posted by Cam:
You've done a lot of work there. I had been looking for outdoor mobility and found the ranger: Lyric Ranger The company, however, is not very responsive to inquiries. If I had your talents, I'd make my own, too.
Registered: 08-02-2009
Posts: 162
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At the KDA Conference, I met two men who both had a Travel Scoot www.travelscoot.com and reported satisfaction with them. Worth a look if you need a small, portable scooter for travel.
Registered: 10-22-2005
Posts: 124
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The Travel Scoot looks like a well engineered urban solution. The small wheels would not work so well in the country, nor is the fine gentleman who developed the Travel Scoot inclined to modify it.
Picture of ToddAllen
Location: Chicago, IL
Registered: 01-18-2008
Posts: 88
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It looks like the Travel Scoot achieves a very compact fold is easy to fold and unfold and at a light weight. 7075 aluminum is a premium frame material. I expect it is a good choice for those desiring a light compact folding scooter.

The obvious tradeoff in the design is the small wheels and motor. It also has a long steering tube supported just at one end which limits the frame to use on smooth surfaces at low speed.

I'm planning to build a scooter similar to the one in my posted photo but with a lighter motor, wheels and frame. I expect it to be lighter than the Travel Scoot Deluxe with more cargo capacity and able to handle rough pavement, modest off roading, curb hopping, etc. with a 15+ mph speed. The tradeoff I'll be making is no folding though it will be small enough to fit in a seat or the hatch of my wife's car.

I'm getting a lot of satisfaction from the design and building process, much like someone who has discovered painting or sculpture and pursues it as a passionate hobby. At this point, even if I stumbled across a commercially built scooter exactly tailored to my desires I'd still go on building.

I have plans to add to my scooters cargo racks for carrying long tubing and sheets of plywood. I want a scooter mounted small electric snowblower with battery power as it looks like we may get repeats of last year's extreme winter here in Chicago. I want a scooter mounted lawnmower for next summer. I'm considering other possibilities like a power shovel and a crane arm for hoisting loads heavier than I can lift.

One exciting thing is technology similar to what has enabled anyone to write, typeset, print and publish is now enabling anyone to manufacture. At the hackerspace club I joined I have access to a commercial mill and lathe, a cnc router, a laser cutter, a vinyl cutter, 3d printers, etc. Last night the space voted to acquire a used cnc Bridgeport knee mill and retrofit it with modern electronics and software. I'm hopeful that at least for a while advances in tooling and tech will outpace my physical decline enabling me to keep building.

quote:
Originally posted by Dan:
At the KDA Conference, I met two men who both had a Travel Scoot www.travelscoot.com and reported satisfaction with them. Worth a look if you need a small, portable scooter for travel.
Registered: 10-22-2005
Posts: 124
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Weight is an issue. The ranger is close to 80 pounds, plus I don't know if it folds up with the seat attachment. The theory is to be able to fold and put it in the car/RV without ramps. It would also be nice to have a seat with a backrest. I'm envious of your skills/passion with this project, keep us in touch, I'll be watching with interest.
Picture of ToddAllen
Location: Chicago, IL
Registered: 01-18-2008
Posts: 88
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Cam,

I saw a spec of 63 lbs for the ranger, though perhaps with options such as the seat it might be more. I'm guessing that 10 to 15 lbs is battery weight. If the batteries and seat are easily removable then it might be more manageable to load/unload.

It looks like the handlebar stem telescopes, if so perhaps you can collapse it down enough that it fits in your vehicle without folding?

I considered a backrest for my scooter but found when riding I don't miss having one at all. When sitting stationary a backrest would help, but I usually transfer to a chair if I'm going to sit for long. Perhaps as my disability advances my ways of using it will change and I'll desire a different design.
Registered: 10-22-2005
Posts: 124
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Hey Todd, what's the dimensions and weight of your trike? Have a name for it?
Picture of ToddAllen
Location: Chicago, IL
Registered: 01-18-2008
Posts: 88
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It's 21" wide, 37" long and the seat height is 24.5". Weighed 39 lbs without a battery and prior to adding the cargo crate (adds 4" length), lights and voltmeter. I'll be adding fenders and brackets for mounting other accessories. I guess when it's complete and loaded with the smallest battery I use it will be about 45 lbs. The next one I build with the goal of reduced weight for easier loading in the car I'm shooting for 30 lbs. Most of the weight reduction will come from using a lighter motor and lighter wheels and tires.

I call it BS3. BS being short for bucket scooter. BS0 is a bucket on casters that I use in the kitchen when reaching into fridge, oven, dishwasher and cabinets as I'm not good at bending down anymore. BS1 looks a lot like BS3 but smaller and lighter. It's currently my preferred scooter for use with the car, but when I build my next frame will be cannibalized for parts to make BS4. BS2 was built for speed with a stiff aluminum frame triangulated through the bucket and a narrow 10" wide rear wheel base to make it easy to lean/tilt when riding around corners. It worked well at speed but was tippy and awkward around the house and yard. It was cannibalized to make BS3.

This message has been edited. Last edited by: ToddAllen,

bucket scooter 2
Registered: 10-22-2005
Posts: 124
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Hey Todd, your BS3 is certainly a useful and well thought-out vehicle. Ever thought of selling one?
Picture of ToddAllen
Location: Chicago, IL
Registered: 01-18-2008
Posts: 88
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Cam, I've only built 3 in two years. Here's a pic of my 1st one.

I've been asked many times if I want to sell my scooters. Somewhat surprisingly I was asked the most about my first one, I'm guessing because it looked the least professional people expected it to be inexpensive.

I've thought about it. But I would have to get a lot better at building them before it would make sense. When building one offs I don't get any discount on the materials or components. And it is time consuming. When building for myself I don't consider the time and labor as a cost. The hours are my 'free time'. I only do it when I feel like it.

I've learned with each build. I have ideas to try and the possibilities are rapidly expanding as I learn and my tools improve. I'm excited to soon have use of a computer controlled mill which will help making precise parts repeatably with less time and effort.

I want to keep building. If I manage to outpace my advancing disability and keep building better and faster then I might get to the point where I want to go 'professional'.

quote:
Originally posted by Cam:
Hey Todd, your BS3 is certainly a useful and well thought-out vehicle. Ever thought of selling one?


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