Hello. This is my first post here, and I was wondering if some of the members here could help me out with a project I am doing for my 9th grade physics class. It is called a Rube Goldberg, which is really a complicated machine that completes a simple task, or in my circumstance, making lemonade. Of course, one of the steps is squishing a lemon half to make juice come out. I can't figure out a simple and cheap way to do this. I am not that knowlegable in pneumatic and hydraulic actuators and things of that sort, so any ideas would be helpful.
Also, I have to be able to slice a lemon in half. What I think I might do is attach a sharp blade to a rat trap (yup, sounds dangerous huh?), and have it be activated by a small car actuator pulling on the trap release. Please give me some suggestions and ideas. Thank you very much!

 

Have you considered using a motor to turn the screw of an old bench vice? Or to lower a heavy weight from a winch?

For slicing, might be safer to hold the blade stationary and move the lemon.

 

Sounds like a slingshot deathtrap. "Flying razorblades!" As far as squishing a lemon, if you wanted to get real fun you could setup a pully system with a very heavy weight and have a motor pull it back up. Eye shields required for nasty lemon stings.

 

reminds me of prince of Persia games
why dont you come up with some sort of chainsaw like mechanism something like rotating blades.
of course dont make one that powerful or u'll be able to chop lemon tree instead -_- v.
or
simply roll the lemon over to a firecracker and ignite it
wont taste good but will certainly serve the dual purpose of turning lemon into pieces and extracting juice out of them

 

A type of guillotine seems like it'd be a lot safer than chainsaws and flying razorblades . Have the lemon fall on the center point of the blade, and an optical switch kick on a motor that draws up a blade and drops it straight onto the lemon.

 

Ya the weight idea sounds good. Thanks for the advice. I have come up with a lot of new ideas for the cutting part, thanks to you guys. Just have to figure out which one is best.

 

One might note that a small slice on the lemon would do the job. the clamp Idea is great for the sqeeze. you might use a piece of PVC pipe as a guide for the lemon so it will not fall out while sqeezing the lemon. The slice can be accomplished by a radial swipe of a sharp blade

 

Or better yet you could mount a blade parallel to the tube that would slice the lemon while being forced between the jaws in that tube.
I understand that this is suposed to be difficult so you may not be able to use any of this.

 

What about a longitudinally split piston shoving the lemon past a blade into a tube with a grate on the other end? After squeezing, move the tube from over the pitcher to over the waste-bin, open the grate, and out pops the dead lemon.

 

"Oh, squeeze my lemon, until the juice runs down my leg."
- Robert Johnson

 

I could just introduce you to my mother-in-law.

Give her an ounce of gin and she'll slice and squeeze a lemon. Totally reflexive behavior by now.

it's
automatic

Give 'er another ounce of gin and she'll repeat.

..the fun never ends.

 

Sounds like my wife with tequilla and limes. Any way we could alter the light to make the lemons look green?

 

Of course, one of the steps is squishing a lemon half to make juice come out. I can't figure out a simple and cheap way to do this. I am not that knowlegable in pneumatic and hydraulic actuators and things of that sort, so any ideas would be helpful.

For that you don't need the power of hydraulics. A simple motor driving a worm (perhaps through a down step gearbox) can deliver the crushing force you need. Remember that shaft_power = rotational_speed x torque or shaft_power = linear_speed x force. shaft_power is the power actually delivered by the motor.

 

ok, really now... why don't you just make your 9th grade instructor's day and come up with something like this.... (and keep a straight face now when he/she asks you if it was your own idea, y'hear?)

... during a viewing of Alberto Gonzales' recent congressional testimony in response to his involvement in the recent state's attorney firings --- run a dummy cable from the playback device to a commercial citrus juicer.

While the class is held in rapt attention to this choice spectacle (yeah sure, american 9th graders, or their parents for that matter), and the juicer is cranking out a delightlful beverage, you can verbally expound on the wonders of modern science,... our ability to harness technology to manufacture lemonade out of pure horse___t.