**Id just like to say first off that my electrical knowledge is very limited, and I'm sort of feeling my way around in the dark. If you have a better way of doing this, I'd love to hear about it. Also we are taking ideas for what to power.**

**(UPDATE) The swing set performed well at the Bay area Makers Faire this past weekend 5/21/11. Having replaced the 44 tooth driven gear with a 112 tooth gear we were able to produce around 9 volts consistently. At 6 volts we had 0.3 Amps and 1.2 Watts. We were able to run 12 volt LEDs well, as well as 9 volt EL wire, and a 9 volt electric keyboard at the same time. We believe that with an additional gear reduction we will consistently produce 12 volts. Look for it*

*deep in*the outer Playa this year. Here is a video of it at the Makers Faire:Also, this is my first Instructable so please bear with me. Hope you enjoy it.'

This project was done in Collaboration with and would not have been possible with-out my good friend Ryan Alpers.

Also I would like to thank Reid Johnston, Matt Gil, and Baker, and the good people at Bearing Agencies in SF for technical insight.

And Thank you to Cork Marcheschi for the use of his studio and equipment.

*(

*UPDATE)*

**I wanted to make clear that the magnet rotor plates are very heavy and act as a flywheel, smoothing but not "bumping" the power. Also the chain does not move back and forth, but in a single direction. The swingers only affect the drive shaft when they swing forward, on their return trip the roller clutches freewheel back, also allowing the swingers to regain momentum. Thank you for all the interest!**

After building Hugh Piggott's http://www.scoraigwind.com/ Axial Flux permanent magnet motor and adapting it to a stationary bicycle, i wondered what else i could use to make small amounts of electricity. After polling friends and family for old play ground equipment, a friends parents donated an old swing set. It was built ages ago but super sturdy and after a little TLC it was ready for a new life.

The design was pretty straight forward, i used Mcmaster Carr and some local (San Francisco) companies for the machinery. It basically went together over a couple of weekends. I used Hugh Piggott's generator since i had already made it and like the design for low speed low torque applications, but i guess anything else like an alternator or treadmill motor would work as well.

Materials used included 4 pillow blocks, 4 roller clutches, 9ft of keyed drive shaft, standard steel tubing, around 20ft of angle iron, a lot of lag bolts washers and nuts, a rear bicycle hub with a disk brake attachment point, a couple single speed rear bike gears, some motorcycle chain, a bunch of shaft collars, 4 pipe collars, and a gear that fit the drive shaft.

tools used included a standard 110 mig welder, porta-band, files and rasps, rubber mallet, angle grinder, misc hand tools like screw drivers etc, drill press, hand drill, marine anti-rust spray, plumbers wrench, vise grips, and a motorcycle chain breaker and assembler.

**Signing Up**

YOU'VE HARNESSED KID-POWER!! *AND* made it FUN!! You ought to get a Nobel Prize or something.

Success with my swingset - pumping water at 3 liters a minute - videos here...

http://www.instructables.com/id/A-Garden-Swing-Powered-Water-Pump/

And here's another swingset being used to pump water, this time in Africa...

http://www.youtube.com/watch?v=Oictq_v_kN4&feature=related

How's yours coming along?

In step 10, you mention the length of the chains affecting the speed of the drive shaft turning...

The length of a pendulum directly affects the time taken for that pendulum to complete one "swing cycle" or "period"... the longer the pendulum the longer the time taken to complete one period.

There's a mathematical formula to calculate this period - it's

T=2π√L/g

where:

T = period

π = 3.142 (Pi)

L = the length of the pendulum

g = 9.81 (gravitational acceleration)

there's a website with an automatic calculator here http://easycalculation.com/physics/classical-physics/simple-pendulum.php

A 2 meter long pendulum takes 2.84 seconds to complete 1 period, which gives 21.1 periods per minute.

Based on a swing arc of 90 degrees, work out the amount of travel made by a point on the circumference of the pivot gear, "x".... x = (πd)/4 where d=diameter of the gear.

Work out the circumference of the smaller gear, "y".... y = πd

Divide x by y to get the amount of revolutions made by the smaller gear for 1 pendulum swing, and then multiply that by the periods per minute to get the rpm figure for swinging at a 90 degree arc.

For us, using the rim of a bike wheel at the pivot to drive a toothed or V belt which in turn drives a BMX freewheel, and using a 1.5 meter pendulum, the Math gives us an rpm of around 90 at the freewheel, which is perfect for our purposes.

Variables:

Length of pendulum

Diameter of pivot gear

Diameter of smaller gear

Swing arc degrees

We've set ourselves a deadline of 2 weeks from today to get this up and running and will post details of results when we have them.

Thanks you very much for taking the time to reply with those calculations! I am very excited to see how your project turns out.

I would expect since the pendulum in this case is a self powered swinger, and not simply gravity, the timing will be different than your formula would suggest. Since the arc will be generally be longer than 90 degrees, and the swinger can speed up and slowdown as they wish.

That said, I think those calculations will be a great starting point.

I also agree with you that the solid bars will reduce thrust loss in each chain link.

I am beginning to build the second version of the swing set now and am only useing car parts and bicycle parts as would be available in developing nations. Having learned the lessons of the first prototype i think that this second one will be more efficient, cheaper to build, and easier to source parts for, taking it out of the realm of an art project and into a possible source of power.

Please let me know how your project goes, i am very interested in seeing your results.

Thanks,

Cleveland

In looking for a motive power source for our project, we came up with and discussed this idea. We've done enough of the Math to know that it's viable for us.

We don't have the access to the type of parts and engineering that you have, though, and will be making this from readily available components - mainly bicycle parts.

A 27" bike wheel at the pivot driving a BMX style freewheel would give around 2 rotations of the freewheel for one pendulum swing - flywheel regulated to try to avoid too much variation in output - that's what we're aiming for.

Nice to see that the idea can work.

A thought, if I may... as an offshoot of this, if you ditched the electrical generation side, you could power most anything requiring a low rpm rotational movement if you add weight to the swing seat to up the torque generated.

Also, solid bars instead of chains would be a definite efficiency improvement.

You have a good, solid project here - all the best of luck with it!

Aziza's Place, Cambodia

http://www.instructables.com/id/Coil-Pump-V20-testing-rig/

&this step.................

You could make a linear generator and use the substantial speed and arc of the swinger to really generate some juice. Plus the higher you swing the more juice you will get. There are several ways I can imagine how to accomplish this feat while allowing the swinger to swing naturally. I'll let you work on how that may be accomplished but, it is very doable.

You would need to deal with the polarity reversals in such a setup but you could also handle that several ways with your obvious ingenuity and electro mechanical skills.

Great, and creative Instructable. Thanks for sharing it with us all.