windmill composter

[JOR_EL]

The first post by JOR_EL on the "Lazy garden" thread(6/14/01 - 10:51 am) asks about windmill powered rotating-composter possibilities. That sub-thread has about 5 posts at the time of this change. (catch-up by clicking "flat" on the thread, and reading these /w3tcompact/icons/tongue.gif ).

I'm moving/retitling it to hopefully attract the interest of engineer-types, who may not be reading the "garden threads".

All ideas on the topic, brilliant or otherwise are most welcome /w3tcompact/icons/smile.gif !!

Larry

 

[StoneHeartFarm]

Good idea! My poor melon needs all the help it can get when it comes to trick stuff like windmills. Maybe we can come up with a brilliant design between the bunch of us and Muhammad can market it! Gosh, if he could sell enough of them, maybe he'd even give each one of us a shiny new tractor with our name on it! /w3tcompact/icons/laugh.gif /w3tcompact/icons/laugh.gif /w3tcompact/icons/laugh.gif


SHF

 

[RobS]

Larry, I think the biggest issue is the biological aspect. Should the compost remain still for a period, and how long between rotations? Other factors are the mix of "greens" and "browns", oxygen and moisture.

The windmill part shouldn't be too bad. There are a number of ways to rotate a drum with a windmill. The drum itself will have to be on some sort of bearing system to support it, contain it and make it relatively easy to turn.

You could use a farm windmill set up for pumping water. The rotor turns a crank which provides up and down motion at the pump rod (terminology?). The drum could sit next to the pump rod with a ratchet gear all the way around the drum. A ratchet tooth on the pump rod could engage and rotate the drum a little bit for each crank revolution.

Other options could include a worm gear drive and chains/belts driving directly.

The engineering behind it will be the power required to rotate the drum versus the power generated by the windmill, neither of which I have any clue about.

It seems to me, if you have the drum supported decently a quick roll by hand every week or so should be all it takes.

The county I live in has annual leaf pickup in the fall. They compost all the leaves and give away the compost to residents. Even on that large a scale, it's done "manually". They turn the long leaf piles once or twice with a front loader and let mother nature handle the rest.

So there's the typical engineering answer: Talk to someone else (biologist) and apply the KISS principle (Keep it Simple, Stupid) /w3tcompact/icons/smile.gif

 

[RPM]

A few thoughts ...

1. You might be better off with water power if you have a stream available. Sounds like a few members are up in those thar hills!!

2. The gearing would be quite simple - you should probably consider a worm-gear. This would drive a couple of rollers that you could sit the barrel on - and turn it. You can see how a worm and wheel gearbox works in the diagram here. As the worm (the screw like gear) turns /w3tcompact/icons/crazy.gif it gradually rotates the wheel (larger round gear). Depending on the pitch of the worm thread and the diameter of the wheel you can get a very large torque multiplication effect -- some will handle over 1000x. It's a useful trick when you have high speed, low torque and want to convert to low speed, high torque.

Here are some other links to small worm gear drives - and other examples.

You could probably use the worm gear out of an old garage door opener if you went this path.

3. You could also rip some old components out of a car and add a few bits and have the windmill charge a battery - and the battery hooked up by a timer to a starter motor - and have the starter motor rotate the barrel. High torque and all that good stuff ...

Hope this gets the discussion going ...

 

[StoneHeartFarm]

Rob, I like your thinking. KISS. Remember, we got a bunch of dumb rubes like me gonna try building something. Probably out of spare parts. (Think Red Green).

Worm gears might be do-able. Just might be. Don't suppose there's much hope for an old car axle, huh? No worm gears, but we got some other gears. And, they're readily available for a song. Gotta think cheap here guys. No use diverting funds away from the tractor. /w3tcompact/icons/laugh.gif

SHF

 

[RPM]

<font color=blue>All ideas on the topic, brilliant or otherwise are most welcome </font color=blue>

Oh well, guess mine fell into the 'otherwise' category!

The challenge was just too interesting to apply the KISS principle right off the bat!

 

[toddler]

Hey RPM,
I think your idea is good. When I first suggested this in the other thread, I hadn't considered a traditional windmill. Don't know why not, but it doesn't seem like a commercial possibility. The picture in my head when I wrote that response, only partially is jest, was an overgrown air-speed-indicator. I figured you could mount it on a vertical shaft with a worm gear, tangential to the circumference of the barrel. For the other gear I pictured a sheet metal ring, mounted to the barrel with grooves cut out of it. The ring could be flat on the barrel bottom, or around the edge. If the barrel is 36" in diameter, the circumference is about 113". Using a worm gear that moved it .25" per rotation would give about a 1:450 gear.
My error, was not realizing it could go backwards. The idea in my head would never get anywhere. Who mentioned a ratchet. Brilliant! Clearly we'll need agitator like fins on the inside since this could turn awful slow.

I think this seems feasible. I've seen little rings like the one I described on toys. Where would you find a big one? I'll bet we could get enough torque with some 3' dowels with my old mixing bowels mounted, with their bottoms vertical, to the last few inches. It'll look greeeeaaat with 4 different sized bowls!

More seriously, if we come up with a good plan, I'll do a patent search at UVM's patent library. My guess is it's been done, but if not, it's probably worth doing.

Todd

 

[RPM]

If you used an anemometer (what a mouthful) like setup then you could probably do it quite cheaply. I'm assuming that this is what you mean - with the half 'balls' or cups usually at the end of three 'spokes'. This is all in the horizontal plane / laying flat.

(Some of the big wind turbines use a similar setup but instead of cups they have large vertical vanes.)

The trick would be to make the 'cups' (vanes), arms and shaft on the anemometer as light as possible. You want low inertia so that the assembly will rotate at low wind speeds. You want them to be stiff though - they will be carrying a load. Perhaps fiberglass would be good for the vanes - it could easily be formed to the desired shape. Probably some sort of hollow tube for the vertical shaft and some nice free-running bearings.

For the worm-wheel pair at the bottom of the shaft you would want to spend some time thinking about lubrication. If they aren't lubricated you'll have losses due to friction (they'll get rusty too). If they are in an oil bath then you'll have losses due to churning viscous oil. Perhaps have the shaft entering (via a seal - rainwater is going to run down the shaft) into a small box that holds the pair - and have just the bottom of the wheel and the tip of the worm in the oil. The rotation of the two should draw enough oil up into the contact area to be effective. If things are really whipping around you would also get some splash lubrication going.

Let's see - you probably wouldn't need a tower either - you could mount this on the side of a barn. One mount bracket plus bearing up high and another down below.

For the barrel it would be easy to make a quick frame out of angle iron. You could have two rollers on the frame - one free rotating and the other driven by the worm-wheel pair. With the barrel sitting with it's long axis along the length of the two rollers you should get a nice rotational effect.

I'll have to look up some of my old reference books for the efficiencies of the gear pair and bearing losses so it would be possible to calculate size of vanes etc. That might take a couple of days (time to go into the basement).

By the way - I wouldn't worry about the worm gear going in reverse. It's almost impossible - the torque multiplication works both ways. Many designs take advantage of this.

In fact, the only instance I know of when you can't trust this 'brake effect' is for the heavy lift jacks that they use in mines. There have been a couple of instances when a roof has collapsed and made the 'wheel' on the gear pair rotate. On a very high reduction drive this accelerated the worm and the rest of the drive train to several thousand rpm with disastrous consequences. Doesn't happen under normal loads though.

Certainly if you pick up a small sealed worm-wheel unit you will not have a chance of rotating the pair by trying to turn the wheel shaft.

 

[RobS]

<font color=blue>Oh well, guess mine fell into the 'otherwise' category!</font color=blue>

RPM, was that the water power idea? Seems just as viable as wind assuming the water is available with sufficient head.

How about tapping into the heat of the compost process itself? Find a fluid with a boiling point near that of the ideal compost temperature (may have to use a higher pressure system to get the right boiling point). Fluid circulates in a closed loop like an auto AC system. A heat exchanger in the compost barrel collects heat and vaporizes the fluid. The expanding vapor pushes on a piston which turns a crank. At the bottom of the piston stroke an exhaust port opens and the expanded vapor/fluid is released into a condensor coil to return to a fluid state which then returns to the evaporator in the barrel. Could use gravity to return the piston and a check valve coming into the evaporator could let the piston stroke keep the fluid moving.

Lots of details to work out so lets get those calculators fired up /w3tcompact/icons/smile.gif

 

[Hawgee]

All ideas on the topic, brilliant or otherwise are most welcome /w3tcompact/icons/smile.gif !!

Shades of "Mother Earth News"

One idea was to segment a wheel on a horizontal axle. Each segment carried a fluid that would change its mass when heated @ 4:00 to 5:00 approximately. Your liquid would fall from 12:00 to 4 or 5 and when heated, would turn to a gas. Then rising back toward the 12:00 position where it turned to a liquid again with cooling. "Perpetual Motion". Now that would take care of the days the wind was low.
If you lived under the power lines, I would suggest a Tesla coil. You could power any design with crazy killyou watts.
Hot days with little to no wind (as a fireman would know) could power up a sterling hot air motor.
Get your pile hot enough and turn a windmill on a vertical axis. (no wait, some call that a burn pile)
I would go with what has worked best for some other folks. Keep the windmill working to water the cows and keep the herd rotated. That as opposed to keeping all your compost in one pile.
If and when you do get this thing off the ground, make sure your recipe for compost (soil,green matter, moisture) is right. If it is to be wind powered, the neighbors might complain. (oder)
<font color=green>When all else fails, buy a box of worms.</font color=green> /w3tcompact/icons/smile.gif


"What is a weed? A plant whose virtues have not yet been discovered."
Ralph Waldo Emerson (1803-1882)