clearance hole
Technical term in mechanical engineering and manufacturing. A hole drilled large enough for a bolt or screw to pass through without engaging the threads.
This part has a clearance hole for an M6 bolt.
The diameter of the clearance hole is made slightly larger than the outer diameter of the bolt.
A threaded hole; バカ穴 is unthreaded and allows the fastener to pass through freely.
Standard technical spelling using katakana for バカ and kanji for 穴.
Kanji spelling for バカ; less common in technical contexts.
Compound of バカ (foolish, useless) and 穴 (hole). The name suggests a hole that does not perform the 'smart' function of holding a thread, i.e., it is a simple through hole.