"Dave Hinz" wrote in message
...
On 22 Mar 2005 17:15:08 -0800, mike wrote:
1 Why is it that the thread on carriage bolts goes the entire length of
the bolt but not on hex bolts?

Carriage bolts are always going to have a nut on them, I think.
Since you don't know where that'll end up, it's threaded all the
way.

A hex bolt usually goes through a drilled hole, and having
a non-threaded section gives you more strength and positive
location in the axial direction.

The non threaded section can be used as a pivot location on the bolt. The
bolt is really no stronger there than its weakest point. If the bolt
breaks some where else it does little good to make it stronger there.