Monday, September 22, 2014

Lambda Top Spins for almost 10 minutes...




This ridiculously smooth top utilizes an instrument grade ruby (now also a stainless steel BB) to create a nearly perfect point on which the top can spin. From the Kickstarter:

ANGULAR MOMENTUM (L) = RADIUS (MASS x VELOCITY)

This equation is all you need to know about tops. For a given top, the size (radius) and weight (mass) are fixed, so your only variable is velocity. If you want more spin, you need more speed. How fast can you spin it? The (major) factors that reduce spin time are friction and the geometry between the top's "contact point" and the target surface. You get to pick the surface, but I get to pick the contact point :)


The other nifty aspect of this little toy is that is that it is optimized to have a lower polar moment, while still having a large mass to maintain momentum. Back to the Kickstarter

POLAR MOMENT OF INERTIA (Ip) = p(r)r^2dV

6061 aluminum is used for the spindle to decrease the polar moment of inertia...in other words, reducing the amount of force it takes to get the top up to a given velocity. If you remember, the more velocity the more angular momentum...and a longer spin time.

Solid brass is heavy, really heavy. It also machines beautifully. If you recall, mass is another important component to angular momentum, making brass an ideal material for the outer ring.

This all adds up to a top that spins for a ridiculous amount of time. up to 12 minutes in fact, however the video above is about 10 minutes of spinning.