# Thread: Design Problem of Egg Black Box

1. Our design lecturer require us to come out with a black box which can differentiate between raw egg and hard-boiled egg. On the black box, there should be one inlet and two outlets (one for raw, the other for hard-boiled).Dimension constraints of the black box is 500mm x 500mm x 500mm. The power source given are 12 AA batteries (only these, no other power source are allowed), while the actuators are 3 motors (specification of the motors is up for us to decide). We have tried several ways to differentiate the eggs. The density of the egg regarding the buoyancy stuff seems not particularly useful as the density of egg is differ from one another. The only effective way we have tested to differentiate them is by spinning the egg. Nonetheless, we can hardly come out with any mechanism to spin the egg by using only three motors (not to mention transport mechanism of the egg that also require the motors). Can anyone please give some suggestions on the way of differentiating the eggs or the mechanism to spin them?

2.

The egg is placed on two rubber-coated (high friction) rollers (the length of the egg is perpendicular to the picture). The rollers are spun at a carefully planned acceleration, to a certain speed (you do the maths). Then they are suddenly stopped. The egg rolls off the rollers at a speed that will depend on how fast it is spinning. Which in turn depends on its raw/cooked state.

Now, depending on how fast the egg "jumped" off the rollers, it will go down either the upper or the lower slide.

Does this help?

4. The egg sits on a platform that is spun for a second or two by the motor. A timer starts when the motor shuts off. A centrifugal switch closes when the platform comes to rest and stops the timer. A plunger is actuated to knock the egg off the platform in one direction if spin time is greater than the time setting. If not, another plunger knocks it off in another direction.

5. Originally Posted by Leszek Luchowski

The egg is placed on two rubber-coated (high friction) rollers (the length of the egg is perpendicular to the picture). The rollers are spun at a carefully planned acceleration, to a certain speed (you do the maths). Then they are suddenly stopped. The egg rolls off the rollers at a speed that will depend on how fast it is spinning. Which in turn depends on its raw/cooked state.

Now, depending on how fast the egg "jumped" off the rollers, it will go down either the upper or the lower slide.

Does this help?
Originally Posted by Harold14370
The egg sits on a platform that is spun for a second or two by the motor. A timer starts when the motor shuts off. A centrifugal switch closes when the platform comes to rest and stops the timer. A plunger is actuated to knock the egg off the platform in one direction if spin time is greater than the time setting. If not, another plunger knocks it off in another direction.
Thank you for your insightful ideas. :-D Anyone got other ideas?

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