| 2026-02-04 | Gear parts |
| 2025-11-10 | Minor machine parts |
| 2025-07-11 | Machine workers? |
| 2025-03-24 | Small parts of a big organization, in an idiom |
| 2023-07-15 | Unimportant workers, metaphorically |
| 2022-06-23 | Peons, metaphorically |
| 2022-05-22 | Parts of a machine |
| 2022-04-03 | Bits of machinery |
| 2020-11-19 | They turn on machines |
| 2020-09-19 | They go around in circles |
| 2019-02-14 | Teeth not connected to jaws |
| 2018-04-20 | Teeth |
| 2017-01-25 | Gear parts |
| 2015-12-28 | Gear teeth |
| 2015-04-12 | Gear parts |
| 2014-05-31 | Some working parts |
| 2014-04-17 | Teeth |
| 2011-05-16 | Mechanical teeth |
| 2009-03-09 | Gear teeth |
| 2008-04-20 | Lowly workers |
| 2006-05-31 | Unimportant workers |
| 2004-08-03 | Gear teeth |
| 2003-06-13 | Industrial revolution elements? |
| 2000-05-08 | Gear teeth |
| 1999-11-04 | Teeth |