"Advice on installing a small motor in a windmill" Topic

Hello,
I'm currently working on some 28mm windmills for my Quar project. I'm mostly done building the structures using Hirst Arts blocks and I have the harebrained idea to motorize the windmills.

I'm out of my league here. I understand the basics of circuits but beyond that I'm not sure where to start. I'm thinking I'd like about 60 RPM, and the motors need to be no larger than 2" long. To compound the problem I need some sort of rubber band or drive chain to get from the motors at the base of the structure up to the axle- the top of the windmill is pretty thin, not enough space to put a motor up there in line with the axle.

I took a look through a Radio Shack and didn't see what I needed.

Here's some questions:

Should I go for a 60 rpm motor? I'd like to run it off a battery, maybe a 9 volt. I don't really want to gear a motor down. I think I need a motor, battery case, wires, 'drive chain' for lack of a better term, and a switch… am I missing anything?

Where's a good place online to get hobbyist electronics? The thing I anticipate having trouble with is the rubber band or plastic 'chain' to connect the motor to the axle. I need to span 8 inches or so.

I wish I had some genuine nerd friends, or that I'd actually built some science projects back in high school!

60 RPM might be a tad fast for a table top accessory – unless you want your gamers to leave with nicks and scrapes.

Depending on how many motors you want, a DC transformer may be a better solution and give you more control over RPM (or you'll need to put resistors on the circuits to govern how much current gets to the motor.

For a starting point, try micro mark – the modeller's best friend. Failing that – try the RC car and model train hobby shops and see what they can offer.

You may be able to find something among Tamiya's kits and parts, e.g. gears and suchlike:

link

One of the model railway suppliers might do a motorising kit. I've seen it done before. Nock or Faller etc

Like this
auction

or this
auction

I agree with the G Dog that 60 RPM is too fast. You need it to move slower both to save battery and to give the impression of size.

You didn't say, so I'm not sure if you've done it, but you'll also want to put in some sleeve bushings between the axle and the structure. These can be as simple as some Plastruct tubing. It'll keep the axle from ovalling out its hole in the structure as well as providing less friction.

However, an R/C store isn't going to have the type of motor you're looking for. You should be looking at model railroad shops.

Wyatt

Resistors was my first thought, but I'm no expert on the subject.

I think 3 RPM is probably closer to the visual effect you want, however.

60 is more for "dangerous obstacle blocking your path in the alien-filled tunnel" . :)

If you poke around the Hirst Arts site I believe there's a tutorial that features motorizing a windmill build out of their blocks. Even if you decide to do things a bit differently it might at least serve as useful inspiration.

Phil Olley did this and wrote an article about how to motorize the sails in one of the "Wargamer's Annual" publications a couple of years ago. I don't recall which which issue, but perhaps another TMPer will recall this.

I've seen a 28mm windmill that used the mechanism from an old clock from Goodwill – the second hand gave 1rpm which was a perfect speed. The only issue was making the blades light enough to not stop the motor.

Thanks for the thoughts all. On reflection I agree that 60 rpm would be too high, I'll look for something much slower. Good point on the sleeve bushing as well.

I checked out the Hirst tutorial and that gives me some good info- I don't have as much room at the top of the windmill so I'll need to modify the approach somewhat.

Thanks!

you might also be able to recycle one of those rc helicopter motors and gears?

Although I have done nothing with them but stare at them, I have pulled a couple of motors out of worn out electric toothbrushes whose bristles were worn and not able to be replaced. Might work and save you some $ if you have a couple laying around.

Why not let the wind move it?

Thanks again for the constructive advice. I think I have settled on either of these motors, which are small, inexpensive, and I like the 90 degree output shaft.

link

link

The rpm of 80 and 51 respectively are higher than I want after the advice I've received- can I use a resistor to slow it down to about 15-30 rpm, or would I need to gear it down (which I don't want to do)? Is there another method to slow the motor? I'm not sure what the torque needs to be but the load shaft which will carry the sails will be pretty light.

I've learned a LOT about gears, pulleys, timing belts and motors on this little foray!