| Gallery, Projects and General > Project Logs |
| An Electric Bicycle |
| << < (4/39) > >> |
| S. Heslop:
They shipped very quickly. The motor arrived this morning! And it looks good. Even came with a mounting plate and an attachment/ nose cone for a RC propellor. Can't test it until the speed controller arrives from Hong Kong though. The servo tester also arrived and I bought a free wheel from halfrauds. It's exciting when things start to come together, but there's still a ways to go. Thanks once again for the help. |
| vtsteam:
Hey Steve great!! :thumbup: Steve -- just a suggestion -- don't over-rev it testing -- I'd put a load on it like a dummy propeller -- just a good straight grained piece of hardwood, balanced, roughly the size of a propeller to suit. Don't stand in line with it, and be sure to bolt that motor down solidly before applying juice to it -- they can really torque around. Be cautious! Also, those bolt-on prop shafts are usually aluminum -- the loads on a plane motor are primarily axial, and not radial, so be cautious with that setup if trying out something other than a propeller. You'll probably want to replace the steel motor shaft -- I think it's 10 mm -- with a longer steel shaft to take radial loads, and also support the longer shaft in an external bearing. Well, exciting that you're on your way!! :dremel: |
| S. Heslop:
That's a good suggestion. Also supporting the shaft with another bearing wont be a problem now that the original gear plan isn't going to work. I might have to bite the bullet and spend £30 or more on gears. I'm still really surprised by how expensive gears are! The two auctions for lathe change gears I was keeping an eye on ended up reaching nearly £50 so there goes that option too. Maybe i'll get implausibly lucky at the boot sale tomorrow, or at least pick up some cheap power tools to take apart (although I think the motor shaft having a gear milled into the end is pretty standard with them). |
| vtsteam:
What about chain drive? Sprockets and chains are available from tractor/farming supply companies. Have you worked out your wheel size and some idea of what kind of reduction ratio you want to try? The larger the wheel size the greater the reduction needed. Also, how many volts and what type of battery will you be trying? It might be economical for testing and ballpark estimating to just find a used 12V car battery and make a wooden kart and see what that will do, then move on to whatever else you have in mind once you've established a baseline for components. Also, aren't there motorized bicycles that use friction drive against the wheel rim? A clutch and reduction rolled into one, and a pretty big reduction ratio. |
| S. Heslop:
Yeah i've tried a few. I think I might have it sorted though. Placed an order for 2 sets of these. http://www.amazon.co.uk/Repair-Spiral-Pinion-Makita-4100NH/dp/B00EZCQO7W/ref=lh_ni_t?ie=UTF8&psc=1&smid=A50DZI580G3JX If it works out it'll be very cheap! Although the ratio is a bit low, the rear wheel will be turning at about 370rpm if the motor is going at 6000rpm. That'd be close to 30mph and might not give me alot of torque, but i've really got no frame of reference on how much is required and how much the motor supplies. Here's the plan so far though. There'll be a chain connecting the gearbox to the wheel's sprocket. It's a bit of a crazy plan, gripping a sprocket to the center hub (opposite to the existing sprockets) of the rear wheel via an aluminium block. The things I'm concerned about is if the gearbox and motor will fit well in that small space between the frame and the wheel (I don't want to put it too far forwards in case it hits my legs as I pedal) and if there'll actually be enough of a gap to feed the chain through. I might need to make some kind of idler to push it down and out of the way maybe. If it works out it should be a pretty good system though. The two main types of DIY electric bikes i've seen either turn the rear wheel via friction on the outside (which seems like it would have alot of problems), or turn the pedals (which would be tiring to keep up with, but I guess that's more of a power assist for steep hills). The free wheel I bought should ratchet if I pedal without the motor, so I won't be fighting against a gearbox and motor when purely peddling. Boy i'm really using alot of weasel words. I'll honestly be surprised if this works out first try, but i'm having fun non the less! |
| Navigation |
| Message Index |
| Next page |
| Previous page |