bolt to the bran

See bolt (“sieve”).

bolt to the bran (third-person singular simple present bolts to the bran, present participle bolting to the bran, simple past and past participle bolted to the bran)

1. (idiomatic, transitive) To examine thoroughly, so as to separate or discover everything important.
   • 1735, Walter Harte, An Essay on Reason:

     This boults the matter fairly to the bran.

   • 1795–1797, Edmund Burke, “(please specify |letter=1 to 4)”, in [Letters on a Regicide Peace], London: [Rivington]:

     The report of the committee was examined and sifted and bolted to the bran.