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A Swing Set that Generates Electricity

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'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.


 
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ljslittle9 months ago
I just read all 83 comments and I am blown away! What amazing things can be created when so many brilliant minds share thoughts and ideas. I am so impressed. We need other great minds working on everything it would take to get us all of the grid if that is our desire. I have no doubt that it could be done especially with internet sharing like you have done here. Way to go!!!
hoverbored1 year ago
Congratulations!! You've done something I've always wanted to do, but only accomplished perhaps on rare occasions after a show storm {help shoveling...} -

YOU'VE HARNESSED KID-POWER!! *AND* made it FUN!! You ought to get a Nobel Prize or something.
chipper351 year ago
I was highly skeptical when I initially landed on this instructable; however, after a careful read.......VERY GOOD JOB!!
Neolp1 year ago
If you placed an additional generative device on the opposite side of the swing, it would allow energy to be produced in both swinging directions with very little modification to your i'ble here.
orvildiaz2 years ago
sir i m orvil diaz doing mechanical engg final sem!!1 we r doing des project of urs for our final semester...sirr we plzz u to gve us some more knoledge abt des...sir cn we meet on fb??
chuangt2u2 years ago
Morning, Cleveland.

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?
chuangt2u2 years ago
We're planning on using a similar set-up and this is pretty much where we're headed with the Math for this...

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.
Cleveland Motley (author)  chuangt2u2 years ago
Hey Azizas,

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
chuangt2u2 years ago
I like this.

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/
Dr Qui4 years ago
Nice project you are really thinking outside the box. Have you tried a fixed bar instead of the chain, that would allow you to put maximum torque to the thrust bearings and would allow you to drop the seat height back down to give a longer swing stroke. If you check out the mythbusters video of is it possible to 360 on a swing they point out that the you can only 360 on a fixed bar. seems you loose a percentage of your possible thrust on every link in your chain. with a fixed bar you get 100% Adding a massive flywheel something like a car wheel with the tire filled with concrete, would be slow to get going but would store a mass of energy to keep the generator going a a decent speed on your back swing. fixed arms combined with a flywheel would be my 2 cent worth. Fantastic post. Andy.
Cleveland Motley (author)  Dr Qui3 years ago
I think you are on the money with this Dr. An added advantage of fixed bars would be the swings could possibly be permanently "fixed" to the bar in phase with each other which we have found to be the most effective swinging. if they were fixed we wouldn't need to deal with loss of thrust with the ratchet bearings... of course then you'd have these steel bars swinging pretty quickly even if only one was being swung...
Brilliant! Energy from humans. When do you think it will become self aware ?
rt3tech3 years ago
Brilliant! I've often thought of an electricity generating treadmill for pets. So they could earn their keep while I'm at work. 10 minutes of treading drops out a morsel or two of food. :D
Slicerr23 years ago
hey you could scrounge the one one way clutch from old bikes
jmasinter3 years ago
dude hook it up to a flashing light display and bring it to the burn!
Cleveland Motley (author)  jmasinter3 years ago
Look for it in the deep playa, it'll come alive when you swing.
grt573 years ago
Too Darn Cool! Leave it to you California Swingers... LOL
Dr. Pepper3 years ago
brilliant!
what about using solid swing attachments for half the length of the swing arm... this would allow some free movement at the bottom, but also give a longer connection point to make sure you are turning the drive shaft a considerable amount. I think it would also help out in the torque dept, and allow for a larger gear on the drive shaft.
Pale_Flyer4 years ago
if you can get to twelve volts, you could get an alternator, and a surge protector... and charge a laptop, or what ever you want to..... at the voltage you are trying to use now, you could only do things like hand held gaming devices, cell phones, e-readers... portable stuff....... thats my two cents!
I think it would be great if the swing could power a regular emergency generator or battery cells that could be used for any number of purposes.
am230064 years ago
hi i was thinking about making this for a physics project comming up and i was just wondering around what the cost to make this was?
Cleveland Motley (author)  am230064 years ago
 the generator alone i received a grant for which cost around 1500$. the swing was given to me, and the rest of the parts involved cost at least another 500. you could certainly do it cheaper if you could use an exiting generator, but the machine parts like the drive shaft, collars, roller clutches etc, get pretty pricy. good luck, let me know how it turns out.
pz give detale knowlge in this project.
&this step.................
Baytonian4 years ago
Just thinking...

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.
jeff-o5 years ago
I wonder if a flywheel on the generator shaft would boost its power output? At the very least, it would even things out a bit.
It would likely even out the power spikes a bit, but not particularly necessary unless the circuit can't handle them. Sadly, it would not increase output.
Unless you get one of them fancy perpetual generation flywheels... is there more/less loss of power from the circuitry vs. the friction of the flywheel's added mass? ie: does the circuit blow off spikes as heat? if so, it might be more efficient w/ the flywheel, and thus increase net output.
robertmw5 years ago
I have a different approach possibly for the power generation. You could use induction. If instead of having the swing force move a flywheel or such, have a decently large magnet, and have it swing by a wire. if you put it through a rectifier, you can be generating power in both directions of the swing, and there would be WAY fewer moving parts to get your clothes sucked off by! I believe an earlier magazine issue had a project to power your tv remote by using a tube with copper wire wrapped around it with a magnet in it, you shake the remote for a few seconds and you have power. Same idea, just on a bigger scale.
And if they're wearing a watch while swinging... or a cell phon or anything like that... It's gone (: (Unless you have some really weak magnets that won't be able to reach between the swinger and the set)
Umm, im talking about magnets. Not an EMP burst....... I'd keep your Hard drive away maybe...
And credit cards. I rethought your idea and realized I interpreted it differently... It's all about wording! Keep any data things (USB, Hard Drive, Floppy Disks (If that applies), Credit cards, Library cards, Any cards (Not playing cards unless they are microchip-equipped or something)), and yea that's about it. Watches and cell phones are fine.
Ok. I don't think you have a very good grasp on just how strong a magnetic field would have to be to wipe credit cards, hard drives, anything at all from an apreciable distance. You probaby have a better chance of having that happen by using a blender. Look. I'm an engineering student, I've taken E&M. There's no worries about something like that happening with what I'm proposing.
Alright, you're right, I was wrong. (: Now we're both happy?
laminae5 years ago
I'd power a fan! I live in HOT!!! Florida, and would rarely swing out there in that heat!
Redgerr laminae5 years ago
lol ya, swing to power a fan to cool you from swinging :p
laminae Redgerr5 years ago
I don't know where you live, but here in NW Florida, it's HOT, and swingin' don't give off much of a breeze!
Redgerr5 years ago
interesting idea to say the least, grats on making it work =]
Ev5 years ago
Bike technology is cheap, well understood and adaptable. A rear hub has the one way drive and can be adjusted for the number or size of swingers. There are tons of parts in yard sales, shops, community organizations.
bigmike555 years ago
Have'nt read all the comments but I always thought of using one of those exercise bicycles for the same purpose. A contraption such as this, would be smaller and would be possible to use indoors and outdoors as well. This swing idea is fantastic but for some who cannot afford the outdoor space, there should be an indoor alternative. I think I better get cracking on this one.
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