I've recently decided to build an automated aluminum can crusher. I would like to set this up in a small room off of my kitchen, so simplicity and quiet operation are my primary design objectives.

After much research, I've decided to avoid hydraulics/pneumatics. I don't want the noise of an air compressor or hydraulic pump in my house. This leaves me with two design options; an electric motor driving a slider crank mechanism or an electromechanical linear actuator.

I recently acquired (for free!) a linear actuator from a lift chair. It's the type of chair that raises the seat to assist disabled people with getting in and out of it. It's rated for about 300 lbs. and will easily crush a can (I've already crushed a few).

The actuator is an OKIN Betadrive and is rated at 24VDC @ 2.2A. The travel of the moving block is approx. 16 inches. I would like to use external limit switches to shorten the travel to a more usable 6 inches or so and utilize a proximity sensor to detect the presence of an aluminum can. Detection would start the automated crushing process and stop it when no more cans are present. A can chute will hold several cans so I can load the chute and walk away from it while it does it's thing.

Would my linear actuator be suitable for such an application? I haven't started building yet, so I'm still open to suggestions. Any help would be appreciated.

Thanks

 

It might be.

Looks like parts for that actuator are pretty expensive; you sure wouldn't want to break anything and have to buy replacements.

I've built a few pneumatic can crushers that work quite well. I found a couple of large brass pneumatic cylinders at a surplus store, and just had to make something with them. I've attached an image of one of them. It's hilarious to watch it working.

Crushing the cans is just one part of the cycle of events your crusher will have to be able to handle.

You'll have to feed the cans individually into the crusher using some sort of mechanism.

Once a can is crushed, the can will need to be removed from the crush area, whether via gravity or by some other mechanism.

The crush area should be enclosed to keep people from sticking their fingers in it when in operation, yet be easily opened to clear a jam, etc.

A circuit breaker on the motor side would be a good idea to reduce the likelihood of damage in case of a malfunction.

 

When I was in college we used a pneumatic press to make coins out of cans.

 

I agree that the actuator is expensive; about $200 to replace if I burn it up or otherwise destroy it. I'm hoping to avoid doing that.

It will also be much slower than I'd like, possibly taking 15-20 seconds to crush a single can and return to the open position. However, it should be relatively quiet and I'm hoping that the automation will compensate for the lack of cyclic speed. At least I won't have to stand there and wait for it.

I plan on enclosing the crushing mechanism for safety. The can chute will be the only access to the crushing area and will be long enough to hold several cans. The length of the chute should keep fingers/hands out of the danger zone.

Easy access to clear a jam is something I hadn't considered. Perhaps something similar to enclosed cable tray with a hinged front panel could be used for the can chute. A kill switch would have to be incorporated to halt the cycle if the door were opened.

Thanks for the input. It's nice to work out some of the details and safety concerns before I go out and start buying parts.

 

A basic idea for a can chute is attached. I haven't built one, but the idea is similar to a watch or clock escapement. The item on the right is a wire or piece of flat stock that has a pivot point near the body of the chute. Not shown is a microswitch or other sensor to detect if a can is in position.

The idea of the pivoting escapement is to only allow one can to pass at a time. The wire or flat stock would be moved rapidly by a solenoid or other electromechanical device.

The basic idea would go something like this:
1) Cans inserted into the chute
2) sensor detects presence of can, starting the cycle.
3) Escapement activated long enough to allow one can to drop into crusher.
4) Can is crushed by linear motor ram until limit switch is struck, or motor current reaches a threshold.
5) Ram is retracted until limit switch is struck.
6) Crushed can is removed from device via gravity or other mechanism.
7) Loop back to step 2.

 

If you feed the cans by hand, you could crush two cans with each cycle. One can would be crushed as the actuator is extended and the other as the actuator is retracted.

The body of the actuator would be in the middle with a crush area on each end of it. That way no motion would be wasted.

 

Some great ideas so far. I can already see that my can chute is going to require further development. I don't think my original design will feed reliably.

Does anyone have video of a similar project? That pneumatic crusher would be interesting to see in action. I've seen most of the videos on YouTube related to can crushers. I really like the one titled "automatic electric aluminum can crusher" by RS67Man. It looks like he's kept it all electrical, relatively quiet and avoided the speed limitation I'll be facing using my linear actuator. Unfortunately, his design looks much more expensive. I'm not sure the additional speed would be worth the cost.

I think I can start gathering some of the components that will be needed to get the project started. A couple limit switches, relays, a proximity sensor or two and some strut for the frame. I'm going to try to keep the control circuitry 12VDC for simplicity, and because I've got a 12V power supply available to use. I'll update after I get the basic layout complete.

I'm still open to any suggestions that would make the project safer, cheaper and more efficient.

Thanks.

 

shortbus - that's a great idea that would effectively double the speed of the machine and avoid the wasted motion of the retraction cycle. However, I would like the process to remain automated. It will be slow and I don't want to stand there and load cans individually.

Another great idea I hadn't considered. I will definitely try to design this into my project.

Thanks again.

 

I too have a linear actuator to build a can crusher and would like to know if you have made any progress.

 

The nastiest thing about crushing cans is tht theyre never fully empty and end up attracting ants or worse.

I say build a small gas fired pottery oven on your back porch and just melt them into bar stock.

 

You joke, but looking at the price of sheet aluminum I have to say it is tempting.

If you drink diet soda's like I do the other problems go away. I have a plastic one I got as a gift just under 20 years ago that works well.

 

Here is a thought. This is more directed to anyone else that may want to build one and doesn't have access to an actuator. Instead of a linear actuator why not try stepper motors. You could have it drive through gears to ensure enough pressure.

Now I have got myself thinking about one. The amount of beer I drink I should be able to pay for it in a month.

 

The nastiest thing about crushing cans is tht theyre never fully empty and end up attracting ants or worse.

I say build a small gas fired pottery oven on your back porch and just melt them into bar stock.

When you have sufficient bars, melt a large batch, 50 lb, and pour into ant hill of large black or red ants. Makes a verry interesting art object. One student asked" where did the ants go?"--- Ans.-- Poof

 

I say forget this stuff with powerful actuators. Think of the operating principle of a guillotine, but without the blade. You hoist a heavy object up a tower, put the vict--, uh, target at the bottom, and let fly. I'd guess that simply gearing down a motor to raise the weight and adding a trip mechanism wouldn't be too difficult.

But hereabouts, you need to keep your cans intact to get your 5 cent deposit back. If you might get enough metal to melt into ingots, you'd be talking serious money at twenty cans to the dollar.

 

I say forget this stuff with powerful actuators. Think of the operating principle of a guillotine, but without the blade. You hoist a heavy object up a tower, put the vict--, uh, target at the bottom, and let fly. I'd guess that simply gearing down a motor to raise the weight and adding a trip mechanism wouldn't be too difficult.

But hereabouts, you need to keep your cans intact to get your 5 cent deposit back. If you might get enough metal to melt into ingots, you'd be talking serious money at twenty cans to the dollar.

Always the redneck way. Keep tossing them into your truck bed, then every now and then lower the gate and shovel them onto the gravel driveway. After a week or so they're all flat and you make a game out of having the kids pick them up.

 

Hey, I resemble that joke!

I put cans in my car under my car so it will crush them, then periodically pick them up and toss them into the metal trash can in my driveway.

 

I was under the impression that the redneck way of crushing cans. Involved a seldom occurrence of actually using the head. Or forehead so to speak http://www.youtube.com/watch?v=LwACNhDFlyU.
But to the topic. I my contry bewerage cans can be returned for a refund. This is done by a machine. The cans are not crushed but, but rolled flat by a rolling machine. I guess crushing them take more energy, than rolling. And a rolled can take up less space.
http://www.youtube.com/watch?v=yAwVEkWld6E
Here is a funny video about what is really going on inside the machine. Or at least I think it is funny. If you insert the cans to quickly. The machine will sound an alarm. And you have to take the last can back

 

I haven't figured out why they want the cans back intact for those states that require a deposit.

We've never had to institute that sort of program around here, even though many get by that are buried amid normal house rubbish there are people that drive the neighborhoods and pick through the trash for the cans. From experience they know who the high consumers of soft drinks and beer are. We also have separate recycling bins we can set by the curb with our weekly trash pickup, a recycling truck comes around the same day and they sort out the plastic, aluminum and newspapers from the rest then put them in appropriate bins on the truck.

A lot of money in those cans, when I was in college they were only worth a penny apiece but it definitely paid to clean up after a party or to save your own at home. They had machines around town named "The Golden Goat" that would take them in any form and return cash so 8 cases of beer usually meant 1 for free in return. Obviously name brand beer was cheaper back then.

I scored heavily back around 1990. A pizza parlor down the street from where I lived at the time had replaced all their pans (to smaller ones I'm sure) and they piled up all the old ones behind the business. I asked - they said I could have them. If I recall I ended up with over $100 on that deal.

 

From experience they know who the high consumers of beer are.

Australians

 

It is also amazing to see how many folks dont realize that their aluminum siding is ALUMINUM!

When I was living with my parents, there was a year or two where everyone was switching to vinyl siding.

THEY PAID ME to remove the old siding from their yards.

Some houses brought in ~$100 worth of scrap.