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Wednesday, October 31, 2007

Getting A Move On

I had another idea about how to mount the motor and drive the wheel, since I have had problems getting access to tools to try the first one, but I had to think about it for a long while to see if there was any stupidity involved, or any good reason not to try it. I thought of a couple of problems, but found a solution to one, and a temporary fix for the other, until I have access to a welder (and hopefully someone skilled at it's use).

It will put the drive back on the rear wheel, but still on a separate chain, on the *left* side, with a new sprocket mounted to the left side of the rear axle. That's what I need the welder for, but for now, I'm using JBWeld, which may be ok for tests, but I don't know that I could depend on it for very long, given the stress it will undergo.

The second problem I had with this way is that it would require me to physically pull the motor away from the drive socket to disengage it from the chain if I want to move the bike backwards, because the motor uses a worm gear inside, so will not turn at all when the chain runs in reverse (unless I *power* it in reverse, which the switch can do if I wire it up, since it's the window control out of the door).

The solution was to not use the bike-pedals for the sprocket mounting, but rather to use one of the junk bikes' rear wheel sprocket-and-axle assemblies, minus spokes and rim. When it's mounted backwards like I would need it to be in this case (to put the sprockets on the left side), it would make the ratchet inside the sprocket assembly work in the correct direction to let the chain move without the motor moving (otherwise not possible). This is the same thing it would have done when actually *in* the rear wheel that I was going to put on the front of the bike in place of the front wheel, in the original design, it's just going to be at the *motor* end of the chain now.

This would still give me bearings to rest the motor shaft & chain sprockets on, etc, and also give me the ratchet ability of the rear wheel so that I can still reverse the actual rear wheel without worrying about the motor.

So, now, I am using the rearwheel sprocket from the scooter's corpse, bolted to the former spoke mount on the right side of the above-mentioned former-wheel-axle to let the motor's gear mesh with it. It's just coincidence, but they do mesh just fine, and thus the motor can drive the scooter's sprocket, which drives the axle, which drives the sprockets on the left side of the axle, which drives the chain that then drives the sprocket JBWelded to the actual rear wheel axle, which drives the rear wheel and makes me go Vroom.

I hope. :-)

Because of the stuff off the scooter, I have enough parts I am testing out the theory of my alternate drivetrain, the one on the left side of the rear wheel, since I can't test the original design I came up with. I couldn't safely battery-weld the sprocket onto the bike's rear wheel, so I JBWelded it instead for the testing (it will still need to be permanently mounted if this works out); it ought to be hardened enough to remount the wheel on the bike tomorrow morning (it was applied around midday today), then usable by the next day, I'd guess. I still want to twist some good steel wire from the spokes to the sprocket's bolt holes where they line up in a couple of places to help absorb some of the torque/etc that is going to be generated by moving the thing with the chain, but I know it won't hold for all that long with just JBWeld, despite how hard that stuff gets. :-) This current idea still uses the window-crank motor off the Fort LTD, since that already has the reduction gearing built-in. I don't have a way to mount a gear onto the Kodak motors yet (they just have a partially-flat-sided smooth round shaft).

After the rear wheel is remounted, I have to determine the exact chain path and thus where I have to mount the motor, axle, and derailer/tensioner, then build brackets for each. If I'm lucky, I will be able to actually test drive it by Saturday, though I don't expect it to work the first time (probably need a total redesign once I figure out what stupidities not to do :-) ). I also will only be able to drive it directly from battery, as I have no controller built yet (and I can't fix the ScootNGo's, because they cleverly sanded off the markings on some parts, and others were burned too badly to tell). But at least it will be progress, which I am starting to need, with the job search and interviews happening recently.

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