threads remove material , that is backed up by the quill of the Stem.
An option: BBB BHP 20
BHP-20 - Headset parts - BBB **
Is a quill + spacers and the bolt that pulls up the wedge, is itself threaded thru the hex, in the bolthead.
and with that cap bolt the thread-less headset, is functioning normally,
** not sold in US, currently , but ordering overseas is common on this forum.