Well, I don't own one, so someone else will have to do the photos, but I have used one a time or two. After you clamp it to the spindle nose where it can rotate with the spindle, put a DTI on the dovetail and manipulate the arms to get the indicator just above the hole. Position it near the edge of the hole and turn the spindle by hand so that the indicator point swings in a circle just above the hole. Move the table and adjust the swept diameter until it is close to fitting into the hole. When you think it will fit, lower the quill until the indicator is just inside the hole, then continue turning the spindle and observing the readings. Move the table until you get the same readings all around. If the hole isn't round, you have to settle for the same readings diametrically opposed.