Shoulder bolt dimensions

The most common diameter that Hill Laboratories uses is 3/8″. The threads are 5/16-18 so that would be the size nut to use.

We do use some 1/4″ diameter, such as in the drop head piece assembly. The thread would be 10-24 on those.

Any 5/16″ diameter uses a 1/4-20 nut.

Note that the length is the “shoulder area” only and is measured from under the head to the beginning of the threads.