On: Distinguishing Bolts from Screws (2012) [pdf]

[dugditches]

Interesting. Basically if it needs a nut it's a bolt. But if it goes in(be it drilling or an existing threaded hole) it's a screw.

I've never heard anyone use 'square headed screw' when referring to putting a bolt into an existing threaded hole via socket/wrench.

And that typically the shape(no point, square head, tools used) define the name.

[TheLarch → dugditches]

I've never heard anyone call a lag bolt a screw, and yet they are pointed and never mated to nuts.

[tesseract → TheLarch]

I see "lag screw" nearly exclusively in formal engineering or industrial settings. "Lag bolt" seems more like a hardware-store colloquialism.

[Shog9 → TheLarch]

Was just at Ace Hardware picking up carriage bolts yesterday... They were right next to the prominently-labelled lag screws.

I'll probably keep calling them lag bolts too.