I'm designing an aluminum tube with internal threading for a delrin retaining ring. The retaining ring has outside threads that are spec'd as SM2 (2.035"-40). So in the tube part I am drawing a 2.035 circle and extrude cutting to make the ID. Then I go to the Hole Wizard and select threads and select an Inch Tap. From there I assume I want to select a 40 threads per inch size. From a long list I see that there are some #4-40, #5-40, #6-40. All three seem to draw the same threads within the hole.
With a screw the 4-40 screw is a smaller diameter and tighter pitch than a 6-32. The 4 is the diameter and the 40 is the threads per inch.
1) With a tapped hole what does the 4, 5 or 6 choice do? I can select any of them and get the same 40 threads per inch tap on the inside of the hole.
2) If the retaining ring part calls out a 2.035"-40 thread on the outside, should I be designing some larger size hole before I select the 40 threads per inch tap?