This is the fifth configuration change for the "Z" axis limit switch.
During the last round of weld testing it was discovered that the distance of the starting gap between the tungsten electrode and the build plate is crucial.
The initial size of the "air gap" was vital to how the first layer formed.
As is well known with all other types of 3D printing if the first layer goes wrong the rest of the print goes wrong.
As weld testing progressed it was found the "sweet spot" for the air gap to be plus / minus .25mm (.010")
The coarse adjustment was revision 4
Fine adjustment is revision 5