Remathilis
Legend
The description for this 1e Thief function is:
When running 1e, I typically don't allow Thieves to use 'Find Traps' to locate large construction-type traps like pits and such. (Although dwarves have a relevant racial ability that can help them out.)
Other DMs prefer to leverage the DMG's note that "small or large traps" can be found to expand the scope of the function; I prefer the more focused scope, or an interpretation that allows Thieves to act on mechanical/clockwork-type traps where there is access to the mechanisms, regardless of size. More of a case-by-case judgment call. (Actually, I prefer the OD&D approach, where the Thief lacks a Find Traps ability -- it's limited to Remove Trap.)
See, I was coming here to recommend Basic Fantasy and I got caught seeing this.
I guess I'm one of those DMs who like the "Find Traps" ability of a thief. I ALWAYS allow a thief/rogue to find "traps" (be it spells/wards, pit-traps, or mechanical traps) and disarm them with the roll (or rolls). The only exception is natural hazards (quicksand, etc). It lets the thief feel empowered doing his job and doesn't get into the myriad of "what is a small-mechancal trap" arguments that make me want to roll my eyes. Let the thief do his job; steal, trapfind, sneak, and scout dammit! Don't play "Guess that I'm thinking" with the thief player who just wants to know is the dang hall gonna support his weight or not!