About this project
A demonstration of the standard constructive-solid-geometry pattern for a mounting tab: a rectangular base unioned with a cylinder to give a rounded end, then a second cylinder differenced through it to cut the hole. Four sliders drive the shape; four derived expressions handle placement and the cutter. Read it as a worked example of build order, not a part sized for a real fastener.
Size
Tab Width is the parameter that ties the shape together. It is both the overall width of the part and the diameter of the rounded end, since that radius is derived as half of it, so the cylinder meets the base flush at the sides with no step to clean up. It runs from 24 to 50.
Base Length sets the rectangular section, 40 to 90. The rounded end is centred on the far edge of that rectangle, so the part measures base length plus half the tab width end to end, 77 at the defaults of 60 and 34. Part Thickness, 4 to 16, applies to base and rounded end together.
The hole
Hole Diameter is the number to watch, 4 to 18. The hole sits at the centre of the rounded end, so the ring of material left around it is half the difference between tab width and hole diameter: 12 at the defaults, but only 3 if you take the hole to 18 in a 24 wide tab. Widen the tab rather than move the hole; nothing here offsets it from the centre of the boss.
Derived values
The expression variables are what is worth reading. Rounded End Radius and Rounded End Center X place the cylinder from the slider values. Cutter Overshoot is a fixed construction margin of 2 beyond each outer Z face, and Cutter Depth adds twice that to the part thickness. The overshoot is the point: the cutting cylinder is deliberately longer than the solid it passes through, so the difference never has to resolve two coincident faces.