Introduction: Wind Powered Composter - the Green Twist , Exactly

Picture of Wind Powered Composter - the Green Twist , Exactly

This is my Epilog Laser Cutter entry so please Vote if you think the idea is unique and worth supporting.

Composting is the easiest thing one can do to help your community. With a wealth of good soil you, your neighbors, and everyone else is stuck with the predictament of what to grow. Imagine such a world.

The problem is that the standard composter doesn't turn itself, and the average human is too everwhelmed with life's callings to take the time to turn the composter once a week.

Hence the self turning composter, wind powered so no additional power is needed.

I just added a laundry basket to the inside to help churn the soil. It was turning a 3/4 full load with no problems at all. I had to empty it out to paint it black, but once the winds pick up I will post a video of it turning soil.

The gear drive supplies more torque than it would ever require, I used vise grips and tried to stop it turning but could not. I estimate that I applied about 150 lbs with a moment arm of 8 inches and still it didn't stop! The gear ratio is 1255:1.

You will need:

A drum, or other round item that will server such a purpose. Note that I did not have a drum but I did have a large bucket I bought for 3 bucks at walmart.

Plywood-depending on how big you want to go will determine how much scrap you need. I used about a half a sheet of 1/2 inch ply for the turbine but I think twice as many layers would be better.

2x4's or 2x6's-The frame and upright uses about 2-8ft lengths of one or the other.

Screws-get a box of 3in deck screws, they last forever and are very strong.

A junk gear motor with a high gear ratio is also needed.

Tools-I used a drill press, angle grinder, hammer, screw driver and jig saw. My advice, you can never have too many tools.

Time: It took about a day to make this. I actually did it over the weekend but actual time was about 12 hours.

Step 1: First Cut Out the Layers for the Turbine

Picture of First Cut Out the Layers for the Turbine

The Vertical Axis Wind Turbine (VAWT) is made up of many identical layers of plywood. First, I cut out a template from foam and used it to mark scrap plywood for cutting.

Step 2: Cut Out the Many Layers of Plywood

Picture of Cut Out the Many Layers of Plywood

Unfortunately it takes a insane number of layers of plywood to make up the turbine. Well actually it takes only 20 or so, but after cutting out 15 or so, you may go insane. Use the guide to mark up plywood and begin cutting. I attempted to cut 3 layers at a time using a jig saw but the progress was too slow so I ended up cutting one out at a time.

Step 3: Drill the Shaft Hole

Picture of Drill the Shaft Hole

After you cut them out, stack them up and use a drill to make the shaft hole. You can do this individually or all at once if you have a drill press and a really long drill bit. You don't need to be super accurate at all really since the turbine turns slowly and you will be grinding away a lot of material later on.

I used a 1/4 inch drill bit since I used 1/4 inch thread stock for the shaft. However, in retrospect I could have used a larger drill bit (1/2 inch or so) for the same shaft since the layers are compressed together with the end nuts. This would allow for easier re-alignment of the shaft had I poorly drilled my hole to begin with.

Step 4: Decide on Your Rough Shape

Picture of Decide on Your Rough Shape

Once you have the layers drilled out and stacked on the shaft, you can play around with the final shape by twisting each layer a little bit forward from the one below it. If you make up a test rig you can experiment with the different shapes outside in the wind to see which one works best. I chose the simple spiral since it was pretty.

Step 5: Make Your Layers Smooth

Picture of Make Your Layers Smooth

Take an angle grinder and some sanding disc and begin sanding the layers into a smoother form. This is more art than science, so enjoy the task, and where a face mask if you are smart......note my lack of one.

By the way, this is my first attempt at hand grinding the shape and I think the final form turned out very well.

Step 6: Find a Good Gear Motor

Picture of Find a Good Gear Motor

In order to turn a heaping pile of compost it takes a lot of torque, therefore a gear motor is used to convert the low torque the turbine provides to high torque at low speeds. So I went to Astro 2 in Melbourne, Florida, a local surplus store and bought a gear motor for 10 bucks. It has a gear ration 1250:1 so it should provide lots of torque.

Step 7: Hack the Gear Motor

Picture of Hack the Gear Motor

The motor is not what we need, we just need the gear reducer. Instead of taking just the gear reducer, it is smarter to just disable the the motor and use the whole device as it is. This lets us use the bearings and original weatherproof housing as well.

First take the gear motor you found apart. Gut the electrical parts (the rectangular brushings, and remove the magnets with a hammer). You don't care about the motor being a motor and these components only cause friction. Be careful not no damage bearings as you need this running smoothly.

Step 8: Mark the Shaft for Drilling Out

Picture of Mark the Shaft for Drilling Out

The motor will have a drive shaft running into it, thus we need to have access hole in the housing and a shaft hole. Use a center punch to insure a good shaft hole.

Here you see me attempting to hold the center punch and camera at the same time. The center punch indents the metal when hit with a hammer. This dent will guide the drill bit so your shaft hole is about as perfect as can be made without a lathe.

Then drill the housing with a larger diameter hole so the shaft doesn't rub.

Step 9: Drill the Marked Shaft

Picture of Drill the Marked Shaft

The center mark we made before really makes drilling out the shaft easy and near perfect (given you marked it near perfectly!).

If you do happen to miss align the center point mark, you can move your mark a little bit closer to center by angling the centerpunch in the direction you want to move the mark and hammering again. Once the mark is reset, give it a couple of taps of the hammer vertically to clean up the dents.

Now, to drill. I wanted to drill and tap the shaft in place but I didn't have the right tap. So, I drilled the hole to the size of the turbines shaft (1/4 inch) and used a wrap of friction tape to make the connection lock together. The hole I drilled was only about half of a inch deep, but you can pick whatever depth you need per your supplies.

Step 10: Drill the Cap

Picture of Drill the Cap

Like before, the cap needs to be drilled out so our turbine can spin the internal core. I used a 5/16 drill bit but you can use whatever as long as it is larger than your shaft diameter. Making it bigger is a good idea so you can have plenty of wiggle room for murphy and his law.

Step 11: Now Make the Composter Frame

Picture of Now Make the Composter Frame

Given that I do not know which motor you will find, I will just give a overview of what you should aim for. Basically, the drum will roll on two tires at one end and will ride on the gear motor on the other end. The motor output shaft is set in a disc of material of your choosing and this disc is bolted to the drum. The purpose of this disc of material is to spread the load over a wide area, since the plastic most drums are made of is usually very thick. I had a 1 inch thick lexan disc from another project so that became my disc. You can achieve the same results from cutting a disc from a 2x6 or some other lumber.

Now make a frame with two tires attached to one end, and a upright on the other end that leads to the gear motor.

The composter rolls on these two tires.

Step 12: Assemble the Beast

Picture of Assemble the Beast

Use lag screw or deck screws, or whatever you have around and scrap a test rig. Test for alignment of the shaft with the turbine and see if bearing are needed. I ended up using some old bearings from my inline skates and would suggest there use in furture projects. They are cheap and weather resistance.

Once the frame is prototyped, secure tacks with lags and give it a try. My final design sorta took a weird path of development but that is like my life. Depending on resources, your project may or may not look like mine, and that is a good thing. I would rather have it not look like mine since I truely value innovation over replication. But either way take a look at my result and try to do better!!\

I should note, the gear motor was attached to the barrel via a plate with a keyed hole in it. I failed to note that earlier.

Also, I made a video of the system in operation but I had the camera on it's side. I will post a less neck paining clip tomorrow as well to show it operation.


ruthaskinner (author)2015-02-14

I don't get a lot of breeze where I live, but I do get plenty of sun. Do you think there's any way to use solar energy to power the turning mechanism? And if so, how much power would I need? I think the size of the thing seems perfect, since I have a very small amount of space, but get fed up of throwing away so much, and then having to buy compost!

kdunner (author)2012-08-03

Hey thanks for stepping in and answering sangretoro's question for me! Your answer is exactly right.

GhettoEngineer (author)kdunner2012-08-18

No Problem!
You stated that you picked up the motor for next to nothing at a local shop in FL, but I am not finding anything in TX. I've searched online, but the only things I've found are either dissimilar to your or very pricey! Is there an online store you might suggest, or any other advise you might give me and others to find a comparable motor?

rbodell (author)GhettoEngineer2013-09-29

try surpluscenter DOT com

kdunner (author)GhettoEngineer2012-08-20

first I'd lookup surplus stores or junkyards. If you go to a junk yard then try and find a windshield wiper motor since these usually have a worm gear reducer. However, you should be aware that a windshield wiper worm gear set only reduces the rotations less than a 1000:1 so the output torque won't be as high as my setup. But if you take this output and attach it to a bike spocket you can reduce it further with a bit of chain and a larger spocket attached to your composter. If you get my drift just nod. Basically just McGyver the hell outa it. That's what I did, my way isn't the right way, it is just a way.

GhettoEngineer (author)kdunner2012-08-20

Thanks for the response. Yeah, I'll take a look at windshield wiper motors. I know it's no science, but I am finding nothing above 1:100. I had considered bike chain and sprockets. I'll give it a go!

sangretoro (author)2012-06-15

Can you give us a few more specs on how powerful a motor you suggest? Can this turn slowly but still strongly?

1250:1. That is the strength of the motor. For every 1250 rotation input, 1 rotation is output. The fact that the output is turning so slowly in comparison to the input, makes it very strong! He also states that he feels it was a bit more than required to turn the barrel, but I'd suggest not straying from his choice too far.

Hamish121212 (author)2012-01-22

Awesome! Ok - like others I am looking for a gearmotor to build one of these. Are windscreen wiper motors from cars geared down enough to work? Has anyone used a windscreen wiper motor sucessfully - or can anyone answer this question for me before I go out and buy one.

kdunner (author)Hamish1212122012-01-25

well if you can't find one gear motor to do it you can always connect two gear motors into each other. I don't think windshield wiper motors are geared down enough tho, they are usually single stage worm gears which are only 100:1 but.....two wiper gear sets in series would work.

diy_bloke (author)2011-10-25

great idea and done very well. Just two remarks (no criticism) The bin is kinda small for most gardens compostable material yield and i found the easiest way to compost is still to just leave it on a heap, no turning whatsoever. It will compost the way nature has always done it without the help of men.

That said: a great project

kdunner (author)diy_bloke2011-10-25

Thank you very much for the input! I really have been lazy on that project and I think I need to get back to it. I have a new design that has a scalable capacity. I need to find the research paper I once read about the rate effects of these rotating composters. Somewhere on the interwebs is a whitepaper that quantify this value. BUT, I never did similar research so now I guess I have a fun fall project. Indoor controlled enviroment, of course. ;) (author)2011-04-25

I know its been a while, but I was wondering if you may have some ideas. I have a bunch of grass clippings left after we mow the lawn and it would be nice to compost at least some of them. The problem with that is that I would need to contain like 3 to 6 months of clippings. Do you have any ideas for big versions, and also how do you compost just grass. I was wondering if it was necessary to contain or of you can build some kind of box with a stirring device. Obviously this would require a much larger turbine, but that is fine.

Hasersys (author)2010-10-14

Ahh, I like this a lot. Very nice build. It looks nice spinning in the wind like a lawn ornament. HEh Nice to see some one els in the area on instructables. I am in Sebastian.

Mr. Kimberly (author)2010-06-19

Just saw this video on Catapult Design's vertical wind turbines. One metal & canvas design was specifically cited at costing $100, and the blue one is a looker...

kdunner (author)Mr. Kimberly2010-06-20

Thanks for the are right it does look nice. I really hope to post the new version soon....but I have a idea for the gulf oil spill I'm working on right now and that is taking all my time. Again thanks for the research (author)2010-03-17

 That would work great, and it looks very mobile.

kdunner (author)jj.inc2010-03-21

Thx, I hope to begin making the final version soon.  It will look much nicer and will be easier to build.

mpledger (author)2009-08-31

This is really great. Good luck with the next model.

FTJ (author)2009-06-02

Can anyone provide more information on step 6 - Find a good gear motor? I tried to find something online but I couldn't find anything with such a high ratio (1250:1) What was attached to this gear motor? Essentially, I'm just trying to find out what to ask for at a local surplus store or search for online. Any suggestions, model numbers, keywords? Thanks!

kdunner (author)FTJ2009-06-20

Wow, sry for the late reply! I've been overtaken by school obligations again, I just got back from a research vessel mission. Now, about the motor: I'd try to do search junk yards for worm gear motors used for windshield wipers. They tend to have good gear ratios and are cheap. The maker of the motor I used here was: Fasco-von weise gearmotors It was a 50 volt dc 0.5 amp motor with serial number: H032 The model number is: V02575AF33 But any high gear ratio motor should do. I will be doing a remake of this instructable by july 1 (for makezine) so keep a eye out for a fiberglass version of this build!

brianfss (author)2009-05-21

Great Job! Fits right in with the Green Theme. Only one little nit picking thing--Get the rust off your drill press table. Your tools will work better and projects will stay cleaner. Take a random orbital sander with a 150 grit disc--spray the table top with WD-40--Sand for a few minutes--Spray again--change to 220 grit paper and sand again--wipe off with a clean cloth and paint thinner--wipe again with a dry cloth. Use a good paste wax on the table and re-wax it every 6 months or so. Again--no complaints on your project--WAY TO GO!

debpix (author)2009-05-21

Bravo on a very clever idea. I don't know how your final exams turned out, but you deserve an A+ on this. You are right about turning a composter being the biggest chore. I'm looking at my huge composter outside my home office window. The beast sits there empty because I'm too lazy to go turn the handle (or fill it, keep it moist, etc.). You didn't win the Instructable prize (though you shoulda), but maybe you can make your first bazillion $ by patenting and marketing it.

load_nikon (author)2009-05-11

Upload failed.... try again.

ReCreate (author)load_nikon2009-05-19

Google sketchup!

stephenniall (author)load_nikon2009-05-16

I might be getting a small allotment with ma dad and I have a idea for a thing like this but Smaller Thanks this has helped me alot

kdunner (author)stephenniall2009-05-17

Well if it is smaller, you might be able to use a solar panel and a gear motor. That way you get consistent results and a easier build.

stephenniall (author)kdunner2009-05-17

tht isnt a bad idea i have a very strong gear motor out of a old box of car bits i have Bought them all Loads of motors for 2£ (4$) Even a starter motor in the box was well chuffed with myself Anyway That could be a good idea or i could do a verticle Wind turbine to power it Hmm will look into it more Hoping to have it in a small allotment we may be getting

kdunner (author)load_nikon2009-05-11

It's nice to know my idea was thought up by many people. Well, at least two. It gives me hope for humanity to know that at least someone out there thinks as I do. At least on the subject of composters, that is.... : )

bkt (author)2009-05-16

Fabulous! I just started a little garden and really want to start a compost. But with a small yard and busy family the thought of having to turn a tumbler does sort of intimidate me. Anyway, I thought a wind-powered tumbler would be the perfect solution and went about searching for one. I think I'll try to hike up the hole thing so I don't get little curious fingers pinched in the tires. That should also help with getting the turbine higher. And potentially for emptying the barrel... I know very little about composting, but are there supposed to be air holes in the bucket? I think I better do a bit more research before I take the plunge. Thanks for the great and inspiring instructions! I've never been here before but signed up so you could have my vote. Excellent work.

kdunner (author)bkt2009-05-17

Thanks, I love how so many people have come up the same inspiration, to the extent that the search keyword "wind powered composter" unites them here. It will need holes, this is just version 1. I'm working on version 2 over the next week for . Once I get that one up and running you should have all the inspiration you should need.

load_nikon (author)2009-05-11

Glad to see an old idea of mine was brought to fruition. I've always wondered how big a turbine I needed to turn a good heap of compost with what kind of gear reduction. Here's a pic of mine with a few components not yet drawn in... Kinda large and not too pleasing to look at it. I like your idea's compactness and it's design makes a bold statement to the neighborhood.

kdunner (author)2009-05-09

Well I know I said I would update this instructable on Wednesday but it turns out that my last final ended up being on thursday. After that, I took friday and today off to go camping and fishing with my girlfriend, both needed the time away from all things electronic. But now I'm back, so I should be able to apply some hours on sunday and monday to apply the changes suggested by ninapratt, macrumpton, and others. Well, just as soon as I unpack the car ; )

macrumpton (author)2009-04-30

Great idea! I think the frame and the turbine could be simpler but it is really great. To take it to the next level, if there was some way to make it so that you could drop more stuff in without removing the bucket, and if there was some way to have the composted stuff drop out automatically that would make it even more awesome. My idea for getting the stuff in would be to add a hatch (or maybe attach a cut off rubbermaid container and lid) to the center of the lid of the bucket. maybe the way to get the compost out would be a small hole in the bucket covered with a coarse mesh. The small hole would have a cover to keep the moisture in and only open when the hole is facing down. The big question is the best place for the hole. does the composted material tend to sink or float on the uncomposted stuff? Congrats again on a great project. It is on my favorites list.

kdunner (author)macrumpton2009-04-30

Thanks for all the suggestions, I will be implementing them as soon as finals are over, Wednesday of next week. I'm also planning on making the composter have double chambers, so that once one chamber is full you can switch to the other. That way the full chamber will have plenty of time to decompose without new additions, thus avoiding the random uncomposted stuff when you go to use the soil (ie, that banana peel you added at the last moment, but has yet to be digested). Oh Yeah, Just wanted to tell everyone that make magazine wants to run with my Instructable! So keep your eyes peels for the composter in the next few months. ok, now back to wave theory studying, oh yea, good times.

Master Roda (author)kdunner2009-04-30

Great idea. This is worthy of a win.

kdunner (author)Master Roda2009-05-01

Thanks, I tend to think so but I'm a bit bias ; )

rednhez (author)2009-04-29

how do you fill it?it seems like as soon as you open it the compost would fall out.

kdunner (author)rednhez2009-04-30

I will post the update on the fill door as soon as I get some time. It is finals week and I must study or I might spontaneously combust during the exams. I want to make a proper write up for the door and now I'm going to implement macrumpton's suggestions so that will involve changing some stuff around. I will be done with finals on next Wednesday so expect all these updates then.

n3rrd (author)2009-04-27

I think this idea is incredible. My one question is: why the plywood instead of something like a plastic bucket cut in half (such as Build-your-own-Savonius-VAWT) ? Just out of preference?

kdunner (author)n3rrd2009-04-27

Well, first off, all the bucket builds look ugly in my opinion. Second, I like my buckets as buckets, they don't hold much water after you cut them. But mostly it was a choice made by desire to achieve a elegant design that people would WANT to have on display and not tucked away out of site(as is the stigma of composters in general). I wanted to make the composter the center of attention and thus potentially change outsiders opinions on such devices. Basically, I wanted to invent something that made the public WANT to own a composter. And plastic buckets just didn't do that for me when I was initially visualizing the build.

n3rrd (author)kdunner2009-04-29

That's cool. Was just curious, and wasn't intending to offend. :) Thanks for the response.

imagewizard (author)2009-04-25

Saw you at the Dark Sky Festival, My Dad and I were pretty blown away (ahem), by your idea. I suspect my Dad'll be buliding something like this soon! You got my Vote!

kdunner (author)2009-04-25

I'm going to be in Harmony, Florida, for a Dark Skies event from 5pm >12pm, and I'm going to be displaying the wind powered composter. The event is open to the public, so if you happen to be in area (you never know) and wanted a closer look, or had any questions, swing on by. Look for the booth that says green steward energy or complete electric, or the one with the giant composter in front of it, right. I'll be answering any questions about solar as well, hot water and PV, options, cost, rebates, all that jazz. Just in case you had any, or if you can't make it because you're on another continent, or some other lame excuse, then feel free to ask me here, I'll try and answer between cram session.

workhorse149 (author)2009-04-23

Would this also work using a 55 gallon barrel. I want to make a rotating barrel Composter and I like this idea. Your idea is very creative. I was thinking to myself how can I spin the barrel without having to spin it manually all the time. The other problem is my yard is surrounded by houses in a city residential area. Tthe wind does blow mostly from the front to the back. I'm thinking I would have to get the wind catcher up pretty high to catch any wind in the backyard.

kdunner (author)workhorse1492009-04-24

I found out that this turbine actually works very well with turbulent wind. Also, if I had made the turbine about twice as tall I think it would perform significantly better. I plan on updating this instructable with a new taller turbine made of foam (better start up since less momentum) once finals are over. I originally planned on making this turn a 55 gallon barrel but I could not get one in time for the contest, so I had to make due with what I had. However, this led me to a better idea all together; two smaller turners are actually better than one big one. You can constantly fill one of the composters until it is full, then switch to the other. This way, by the time you fill up the second composter, the first one is ready to be emptied. This avoids the common problem of having uncomposted material when you dump it out, because it has had time to compost without last minute additions. If you do it with a barrel, think about ways of making a divider, either perpendicular with the axis of rotations or parallel to it (lengthwise). The parallel solutions would be interesting since it lends itself to the idea of quad bins. When I get some time this weekend I will try and post a cad to help you see what I'm getting at. -kelly

ninapratt (author)2009-04-20

Have you thought of painting the bucket black? My hand-turned composter is black plastic and really heats up fast, making the process that much faster.

kdunner (author)ninapratt2009-04-21

Great idea, I will definitely do this as soon as I get some time (finals are coming up). I wonder though, I am in Florida and I can predict that a black painted drum will get very hot (hotter than most bacteria could survive I think). So ideally a smart shade should be intergrated into this project such that when the temperature is too high it rotates from below the barrel to above it to keep it cool. I'll try to work on this later in the week, now I must do wave theory homework, oh yea, good times!

ninapratt (author)kdunner2009-04-22

Hmm. I'll have to look up optimal temp for composting. I know that my bin (I live by the ocean in New England), in a sun-pocket (protected from wind, facing south-west) gets wicked hot in high summer when outdoors temps are in the 90's. But I haven't noticed any little bacteria tombstones. Maybe I haven't looked hard enough. The black is more stylish, certainly. Nice instructable!

ninapratt (author)ninapratt2009-04-22

The composting community consensus appears to be temps between 110-160 degrees F (40-60 C) are the most efficient. If the pile is getting too hot, it needs to be turned faster to get more air in there. The hotter the better, apparently, as it just means it'll be ready sooner. You could be scientific about this and go out and measure the heat with a good meat thermometer, probing into the center. Or you could set up 2 bins, one blue, one black, filling them with the same organic matter, and see which is ready first. I can see a life time of experimentation in front of you!

About This Instructable




Bio: I'm a senior at Florida Tech studying Ocean Engineering (making wave and wind generators at sea). I'm into electronics, chemistry, all the sciences ... More »
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