Robotic Punching Arm


About: DIYwalkers shows how to make highly functional mechanical walkers via LEGO prototyping and computer simulation.

Puncher battles are a fun classroom activity that guarantee that students will innovate to win! By tuning the bar lengths of their puncher's 4-bar linkage, students can take advantage of "inverse leverage" to throw fast punches to knock their opponent's block off.

Step 1: Before Finishing Your Build, Tune Bar Lengths to Optimize for Punching

The above bar ratio of 2:4 means the fist's speed and distance traveled increases significantly

Step 2: We'll Build a Puncher in Stages, Starting With Bar 2

Step 3: Here Are the LEGO Technic Parts Used

Step 4: Assemble Bar 2

Step 5: Assemble Bar 1 (the Handle), and Add Bar 3

Be sure to use theyellow frictionless pins for joints designed to move!


Step 7: Add a "Block" for Your Opponent to Knock Off

Step 8: Optional: Motorized Punchers

Punchers can also be motorized to make "battle bots". This can be done by programming a servo motor to do a partial rotation, or by adding a crank and a 6th bar as is done in the video above.

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    5 weeks ago

    Nice idea. Keep it up!


    Reply 5 weeks ago

    Thanks MuhammedOruc!