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Can Crusher - Take 2

benheck

Sure, I crushed a can using stepper motors, but turning on and positioning the CNC every time I need to crush one isn't very convenient - I drink a lot of diet Pepsi.

 

What are your ideas for an electric can crusher?

  • This is how the Physics dept at the University of Missouri - KC did it at Maker Faire Kansas City:

     

     

    Can you tell it gave me a suprise? image

     

    Here's a view of their device:

    image

    Look at that nice cap!

    image

    The student running it said they also use it to shrink quarters!

     

    Cheers,

    Drew

  • in reply to fustini

    Wow pretty cool can crusher.  Thanks for posting Drew.

  • Use that actuator you have lying around, like the garbage compactor we worked on

  • in reply to colecago

    Did you make this celecago?   very cool.  I think im going to have to make one for my house.

  • in reply to Nate1616

    No, it was another guy at work on this project.  We just made the electrical controller for it, another company makes the machine. 

  • in reply to colecago

    Even better coleago.  What was the purpose of the machine lifting up like you showed?  was the Cart inteded to lift something?  Just curious.image

  • in reply to Nate1616

    No, the whole purpose of that cart is a demo for our drives.  The 3 actuators were to show off linear position control drives, there are two traction drives, there was another drive used for a conveyor on top we removed.  The point of the demo was to show how you can make a complete system or machine using our drives and off the shelf products.  The only custom piece was the control board that has zigbee on bluetooth on it and controls all the drives via speed and direction commands.

  • in reply to colecago

    thanks for the response celocago.  Very nice job

  • I just rewatched the can crushing episode and had a few thoughts on how to better achieve the goal.

     

    The first thought I had was to do with the strength of the sides of the cans.  With the sides of the cans being perfectly straight it takes quite a bit of force to crush a can.  Push on both ends of a can with your hands, and it's very difficult to start the crush.  Put some dents in the sides and it crumbles much easier.  Putting dents in the side of the cans can be hard to automate and can also result in some very unevenly crushed cans as it tends to fold in the direction of the biggest dent.  Now if you take another can and grip both ends of it and twist them opposite ways while pushing in, it is much easier to crush the can because the twisting motion causes the sides to dent inwards in a very even pattern.  To automate this, you simple need to make the surface the can is crushed against spin and covered with rubber or some other high traction material and have the end of the crush piston be covered in the same material to keep the whole can from spinning when it hits the spinning plate.  You may also want to key the piston to the crush tube to keep it from rotating.

     

    My second thought was with the actual force used to crush the can. While your stepper motor was able to provide the force needed to crush the can, it did so very slowly.  You were very concerned with the direct force applied to the can from the lever/piston from a complete stop.  I don't think that this is the way to go.  If you go slow enough a midsized person can stand on a can, so they can hold a fair amount of weight before they start to collapse, but if you lift your foot up and move it down quickly it doesn't take much effort to crush it.  F=MA is the key here, if the A is small, then it takes much more M to cause the same F.  I propose that if you were to use your final piston idea, give it a more mass and moved it fast, it would provide much more force than a slow moving lightweight piston.

     

    A fast heavy piston combined with the spinning flywheel clutch of doom from my first thought should provide a fast can crushing rig.  Hardest part left would be automating the loading/unloading so that the machine could actually be efficient.  I'm envisioning something similar to an upside down machine gun that uses the motion of the piston to load the next can into the crush chamber, but this would require a long throw on the piston and very tight tolerances.