Historical clue formulations

• Ridge in metalworking — 2025-01-26
• Bit of metal texturing — 2021-08-13
• Small protuberance — 2018-08-17
• Small projecting ridge — 2014-12-13
• Button ridge — 2011-05-22
• Small ridge on the edge of a button or dial — 2009-10-22
• Small knob — 2005-06-06