Introduction: Mechanical Trash Compactor
Hello. This project was a test to see if I could design and create a trash compactor that improved upon some of the disadvantages or design flaws as I see them of existing compactors. The main problem I have with trash compactors, such as those in airports, is as follows:
Much energy is wasted from the seemingly random compaction of trash. Trashcans at airports compress trash when there is still much space in the bin. Granted, very little energy is expended each time a can compresses trash in terms of how much energy powers an airport, but consider the energy lost when 100 to 150 compactors compress trash a minimum of five times more frequently than is necessary, every day. (Note: I used the Atlanta Airport for this example)
Through this instructable I will demonstrate a concept for more efficient waste management that does not require energy from an outlet or power source.
What I used:
1. A 12 gallon plastic trash can (a smaller trashcan will not be able to hold the mechanisms, due to balance issues, space limitations, and plain practicality; a larger trashcan may be better, but I don't expect you to want to keep a 30 gallon rubbish bin in the corner of the kitchen)
2. VEX collars
3. VEX gears (84 tooth, 60 tooth, 12 tooth, sprocket gears)
4. VEX chain belt (length/number of links determined by spacing of gears)
5. VEX metal plates
6. VEX brackets
7. Bolts and nuts (sizes vary according to waste bin)
9. Axles of various lengths ranging between 2 and 8 inches
10. 5/64 hex wrench
11. 5/32 hex wrench
12. Electric drill
13. Scalpel (or other very sharp cutting tool)
14. Augur or bore
Step 1: Materials and Price Constraints
If you do not already have a set of VEX parts and a trashcan from which you are willing to part, I would recommend buying a 12 gallon or larger bin. A larger bin will handle better with a bunch of gears and metal on the side. You can find plastic 12 to 14 gallon cans online for $20 - $50. I do not recommend a metal can because this drastically increases the price. You will also need better tools to modify the can, and plastic is just easier to work with. All of the VEX parts can be found online as well.
Step 2: Small Bits First
To build the system that would raise and lower the can, I attached brackets to the metal braces to stabilize the setup. I laid out the gears in a system that had the 12 tooth gear at the bottom, the 60 tooth gear above that, and the 84 tooth gear above both. The 12 tooth gear will be on the axle of the crank. This decreases torque needed, and increases compression force. The opposite setup would not be able to crush trash. It would spin very fast, but the gears would strip out before any significant compacting occurred.
I attached one 12 tooth gear to an axle about 4 inches long, giving enough space to attach a handle on the outside of the can. This gear meshed with the teeth of the 60 tooth gear, on a 3 inch axle. Also on this axle I attached another 12 tooth gear, which meshed teeth with the 84 tooth gear. The 84 tooth gear was set on an axle about 4 inches long.
With these attached to a single metal brace, I measured the width and height of the hole I would cut to fit the bolts, collars, and plastic brackets.
The spacing of the gears is essential, to make sure that the teeth are close enough together to mesh comfortably. You should not force the teeth together; the spacing of the holes in the VEX metal plate and bracket should be appropriately distanced for the gears to fit. Also, use spacers (I used washers and collars) to make sure the teeth of the gears mesh well.
Step 3: Actually Modding the Trashcan
Trace the outline of the brackets and bolts you just measured in the side of the trashcan at the appropriate height. This is a mixture of personal preference and working with the type and size of the trashcan. Secure the plate to the can with tape, a clamp, or whatever works best for you. Next, mark the four holes at the corners of the bracket in the trash can. It's a pain trying to make a hole in a specific spot with an augur when the hole is moving around. It is also dangerous.
Please make sure your fingers are not behind the spot through which you are about to jab a pointed metal object.
Once you have the holes marked you can remove the metal plate and gears and bore a hole in each of the four spots you just marked. Use the drill to widen the holes, being careful to use the size drill bit that will not be too big or too snug for the bolt.
You cannot substitute a bolt for a screw. The bolt secured with a nut through the metal and plastic brackets will provide stability that you would not have with just a screw, even if you use many more screws in many more spots spaced out around the brace.
Secure the brace on the inside of the trashcan again with your choice of temporary attachment contraption. Secure the brace on the inside to a brace on the outside of the trashcan with bolts and nuts through the holes in the trashcan at the corners of each brace. You should have spacers (again, depending on the type of trashcan you use, you will need different quantities of washers, or collars if you don't want to use washers) between the brackets and the walls of the trashcan, to eliminate and vibrating or shaking that would occur without such spacers.
The axles of the gears should extrude from the bracket on the outside of the trashcan. Attach collars to each axle for extra stability and support.
Step 4: The Lower Limits
You will do the exact same for the sprocket gear at the bottom of the can as you did for the setup at the top, only simplified. Only one sprocket gear is needed, instead of several gears, and you may use a relatively short axle. I used a 3 inch axle. Use smaller metal plates, as large plates are unnecessary.
Make sure everything is level and secure. Everything except the gears themselves should be very stable, and even the gears should not wobble at all. They should only move around the axle. If the trashcan does not have very straight walls, this will be frustrating, as you will need a semi-complicated spacing system to fix that. Try to find a trashcan that will not cause such problems.
Once you have secured the lower sprocket gear/bracket setup, you can grab a VEX chain belt and improvise a bit.
Step 5: The Chain Game
I measured the length of chain I needed to fit the gears by just estimating, attaching, and removing links from the chain as needed a few times until I got the right length. You should not be able to put the chain on and take it off easily without undoing a link. At the same time, it should not be so tight that there is significant tension on the gears/belt.
To attach the compressor, I fiddled around with how big I wanted it to be, how much I wanted it to move, and how strong I wanted it to be. I used steel part for most of the mechanism, but this is really not ideal. Steel is too heavy to use in this part of the can. I did not have these resources at the time, but I would recommend using an aluminum, plastic (ABS/3D printed), or other strong yet lightweight plate as the face of the compressor. My setup has the plate attached to the belt by a hinge-like jumble of metal. The plate can be locked down in place or locked up out of the way with a removable axle which intersects holes in both the rotating and stable part of the hinge.
For this stage, I would recommend improvising a bit and considering what you want for the compressor. If the trashcan opens from the side, not the top, you may have more liberty with what you do with the compressor.
Step 6: Hands on or Hands Off
Finally, it's time to put a handle on the sucker and crank it a bit, compress some trash.
However, if you can't stand the idea of cranking your trashcan by hand slowly and arduously, you can attach your electric drill to the axle of the lone 12 tooth gear and compress stuff that way.
If you want to get technical, attach a motor to the axle and embrace the laziness. I settled for the slightly less option of using a drill. I designed a hand crank to be printed on the 3D printer, and it would work fine if the printer didn't break.
As seen in the picture, I helped turn the trashcan into a crazy-wired double Arduino can that compresses trash, moves around, and displays how full it is.