I thought you guys would find this interesting as a 3D project .

3D Printing
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I thought you guys would find this interesting as a 3D project .

Originally shared by Larry Phillips

The Cardan Gear

The arm of this ingenious mechanism traces out an exact straight line as the gears go through their circular motion.

The small gears must be half the size of the large gear. Also, the arm length must equal the distance from the center of the large gear to the center of the outer gear.

The Cardan mechanism was invented by the Italian mathematician, physician, chess player, and gambler Gerolamo Cardano (1501 – 1576). He also invented the universal joint.

Proving mathematically that the Cardan gear works as claimed makes for an interesting trigonometry problem.

ee3c17ad937dfc8e3b71470017988bdd.gif

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If you REALLY wanna blow your mind, look at some of the samples here:
http://kmoddl.library.cornell.edu/

Grandpa really was a smart cookie!

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Looks like the arm travels different speeds from right to left.

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The most mechanically strange thing I ever saw (keeping in mind I am a EE) was the “key rollover” on a KSR28 teletype. Without getting into details, it relied on a box of ball bearings and pressing a key pushed a wedge into the balls so that no other wedge could go down. Who thinks of this stuff?

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The illustration here is wrong somehow. The arm should rotate twice per cycle instead of just once. Or else the outer gear needs to be twice as big.

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@Phil_Hord No, if it was twice as big, it would “stand still”, i.e. always have the same orientation while rotating around the yellow gear. I think…

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@Phil_Hord it does rotate twice per cycle, but it’s going backwards around the big gear once.

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@David_McGuigan Oh, yes! Of course. I was wondering why someone would design such a nice gif and then screw it up like that. :smiley: Thanks.

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I believe that the linear speed of the moving arm would be consistent throughout the motion cycle (unlike SHM in common rotary to reciprocating motion conversion)