This Melacha Applies to Sifting Wanted or Unwanted Particles. Does the Concept of מיד (Miyad/Immediate Use) Apply to This Melacha?;
more examples of "מבטל כלי מהיכנו" (nullifying a vessel from its normal usage) that come up on Shabbos;
Very Interesting Halacha in Reference to Bells on Shabbos;