Please login or register.

Login with username, password and session length
Advanced search  


Deadline to submit World Contest Videos is October 25th

Author Topic: Fiesty little battle tops in action  (Read 966 times)

Jeremy McCreary

  • ITSA Jr.
  • Immortal Member
  • *********
  • Posts: 2348
    • MOCpages
Fiesty little battle tops in action
« on: March 25, 2017, 01:53:40 AM »

I've been having a lot of fun lately with these simple, essentially indestructible LEGO battle tops. The rotors are made from LEGO wheels.

Release speeds of ~1,600 RPM and the favorably spaced lugs on their striking surfaces give these finger tops a decent wallop for their size and density (overall, less than that of water). Trained the plastic arena to sag in the center like a bei cloth arena to increase the collision rate, but the sag had partially rebounded by video time.

The 20 mm ground clearance seen in the video and in the yellow top on the right above promotes travel in predictable arcs and favors precession over sleeping. The ball tips are essential to these behaviors, which aid in targeting and act to amp up the action.

Spin times are ~25 sec in this battle configuration, but if you eliminate the 14 mm yellow shim between the wheel and the ball tip to minimize CM height and TMI about the tip without changing AMI significantly (red top on left), spin time increases to 45-50 sec and sleeping with little travel becomes the favored spin-down behavior.

Many lessons for top physics here. Details on blog page.
« Last Edit: March 26, 2017, 11:34:53 AM by Jeremy McCreary »
Playing with the physical world through LEGO