Advice on hub for newbie stepper motor project?

[matthew6]

Hi all,

I'm building my first wind turbine using an old bike wheel and one of a selection of stepper motors I have.  I'd like to make something I can charge AAs with.  I'm new to electronics and tinkering in general, but I'm very interested in learning more.  Anyway, all four of my motors (three of them are the hefty ones with thick metal casings and one of them looks like a large hobby motor, which I took out of a printer) have shafts that are either smooth, or have plastic gear heads on them, and I can't figure out how to hook my bike wheel up to the shaft.  I suppose I could use a belt, but intuitively, it seems like running a belt around the wheel would cause a lot of friction and not be as efficient as mounting the wheel onto the shaft of the motor.  And I'm not sure if the motor shaft would hold the belt well without some sort of attachment for that.  

I know this is a very basic and fundamental design question, but I'm getting in on the ground floor, so any help would be appreciated.  I haven't found anything online that covers this in a way that really solves my problem.  I just don't know how to get the motor and the wheel working together I guess.  What parts do need?  

Thanks a lot,

Matt

[coldspot]

Hi

For my mothers yard toy, type, water pumper mini copy.

I found a toy car/truck (Lego maybe)rubber wheel that fit the shaft of the stepper to be used and mounted the stepper so as the little wheel was touching the top of the spinning shaft of fake windmill. Because the size difference isn't much the LED's only light up in strong winds.

 With the size of a bike wheel and a small toy wheel, you could get high volts !.



$0.02

[ghurd]

I am not clear on the wheel and motor relationship.

You want to drive a stepper motor from the rim?  Or the motor is connected to the wheel hub?

Most steppers don't need to turn very fast to get up to charging voltage for AAs.

Driving it with the rim is going to get the motor turning a lot faster than it needs to turn.

Steppers tend to peak out on the output at a fairly low speed.  Much faster motor RPM than the peak output gains nothing, and a lot faster may even hurt.

I'm not sure how large the steppers are, but hanging a bike wheel directly on the shaft can't be a good idea.  Maybe connect the bike wheel to a jack shaft, then connect the motor at the other end of the jack shaft?

Sometimes, a large stepper connected to the right amount of thin metal (blades?) can resonate due to the cogging, and very loud.  Creepy too, like 100 out-of-tune hillbilly hand saw instruments.

G-

[RogerAS]

Matt,

Here is a link to my diary posting concerning your "problem" of attaching blades.

http://www.fieldlines.com/story/2007/4/27/11254/3213

I use parts from dead VCR's. The steppers I used have a nose shaft very close to the hubs of the VCR tape heads, and these hubs screw to the larger aluminum discs of the VCR motor. I "forced" the brass hub onto the stepper shaft with a hammer. My motors have a tail shaft and careful backing and small driving steps made the basic connection easy. Be careful with this method as too much hammer force could damage bearings, shafts, or most importantly the magent(s).

If you need more details email me at;

theropod (at) yahoo (dot) com

Hoe this helps.

R

[matthew6]

Thanks a lot guys.  I will look into some of these ideas and let you know if/how it works when I get around to putting the thing together.  I'm playing with the idea of scrapping the bicycle wheel idea and going with a VAWT of some sort.  I'd like to build something unobtrusive and mount it on the roof and run a wire down into a charging station in the house.

BTW, the previous owners had a TV antenna on the roof that we've since removed.  There is still some coax cable on the roof that runs down into some cable outlets inside.  Is there any reason I can't or shouldn't just jerry rig it to hook into that?