An object detection system utilizes a teach cycle performed with a low-pressure blow-off (i.e. positive pressure) instead of vacuum (negative pressure). During the teach operation, the positive pressure is enabled and the nozzle is lowered to the object. An air sensor detects pressure or flow at the nozzle tip. A rise in pressure or drop in flow is detected as the nozzle makes contact with the object (i.e. just before or just after actual physical contact is made). The height of the object is stored as the taught height to be used subsequently in repetitive operations by the machine. This teaching method is particularly useful for very small objects because the positive pressure does not lift the object.