"Compared to standard hex nuts, square nuts have a greater surface in contact with the part being fastened, and therefore provide greater resistance to loosening (though also greater resistance to tightening)."
I love info like this!!!! 2 More Points
1) A square bolt requires at least 90° of free space, as that's the least amount you can turn it before moving the wrench. A hex bolt only needs you to have 60° of free space, so it's better in a more enclosed environment.
2) Since a normal wrench only puts force on the edges of the bolt head's sides, increasing the number of sides means increasing the area over which the force is spread, thereby reducing wear. This and the issue about elbow-room that was already addressed are probably the main reasons why six or twelve sided bolt heads are the most common.
We found this over at Curbly.com. We were googling the perfect toolbox and this site has an article that lists all the things a tool box (or tool bag these days) should have. Definitely go take a look and see if you've got all of them. Or make sure your Dad does. For Father's Day you can get him whatever he doesn't have on the list.
Found this over at Alphamom.com. Turn an old Altoids box into a teeny toolbox - you need some nuts and bolts for that handle. Maybe that's where dad can store his left over fasteners.
The Smallest BBQ
Our favorite website Instructables.com shows you how to make this bite-size bbq (also using an Altoid tin but not the mints, th Altoid Sours.) The perfect bbq for one marshmellow whenever it is time for S'mores. Those legs are sheet metal screws!