4 Bar Linkage: Part 1


Linkages are hard.  I think they are powerful mechanisms, I just find them difficult to visualize and time consuming to iterate. I’ve been thinking about a device that could turn and push a small wooden block over and over again, and I fear a four bar linkage may be the answer.


I saw a great video from Disney Research on creating animated mechanical characters. Their software appears to be proprietary, but it was a great starting point. Then I found an incredibly useful 4 bar linkage simulator from Mechanical Expressions. Thanks to this simulator, I quickly dialed in the desired motion and got my linkage dimensions.


Drew up some designs.

linkage designs

And milled some parts.

The first prototype is a hand cranked 4 bar linkage built from aluminum and delrin parts. Linkages need to be built well in order to operate correctly. There can’t be too much slop in the mechanism and precision counts. Hopefully, the second prototype will actually move a block around.

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