By thread form - TXCCNCMAN means that it has to do with the fact that the tool is spinning in the spindle on a fixed Z plane. When you start to introduce a 3D move to cut the thread, the bottom of the tool is dragging on the thread geometry as it enters the cut and the top drags on the thread geometry as it exits the cut.
So the tool is not actually cutting in the shape it is ground.
Physics dictates that this is more pronounced as the diameter gets smaller.
Your 1/4 cutter will likely cut a thread on 1" that is much less than 60 degrees.
No harm in trying if you want.
www.integratedmechanical.ca