Hurdles: On Building Split-Rail Fences and Portable Fences

An expert on vintage (i.e.: pre-power tool) hand crafting techniques describes the process of building split-rail fences and "hurdles" or portable fences.

split-rail fences, portable fences - using a twivil to make a mortice hole
A twivil is a tool specifically made to clean out mortice holes.
Roy Underhill