The top of the hole is sometimes partially or fully buried inside the model, depending on the geometry of the model and the selected references.

To ensure that the entire top of the hole, including holes that have a counterbore or a countersink at the top, intersects the outside of the model, use the Top Clearance check box:

When the Top Clearance check box is selected, the top of the hole feature extends outward using a cylinder with a diameter equal to the top of the hole, and removes material so that the top of the hole intersects the outside of the solid geometry. The cylinder uses the diameter of the counterbore or the countersink when the hole includes these elements.

The default_hole_top_clearance configuration option sets the default state for the Top Clearance check box. The default value is auto, where the system automatically determines the state based on the placement references, but you can select yes to use top clearance by default, or no to not use top clearance. When the option is set to auto and you change the hole placement references, the top clearance state changes along with them, but once you change the Top Clearance check box manually, the automatic setting no longer applies to the current hole. The configuration option applies to creating a new hole, but not to editing the definition of an existing hole.

The auto state of the default_hole_top_clearance configuration option is particularly useful for creating holes in the following cases:

In the following example, a hole is created using a datum plane and an axis for placement references. The datum plane is below the top of the model.