It’s so easy to make a center hole, but what is the precision of position.
I shall explane how to make a good position of the center.
1. Make with a felt pen the surface blue or red.
2. Make a cross on your material. OK It’not the right way to do it with a Caliper. This is not a new one. One of the claws of the caliper i have grind sharp.
3. Feel with the point of the centerpons that you are in the center of the two lines.
4. Hit the centerpons gentle with a hammer. So now you have a little hole.
5. Look with a magnifying-glass that the point is in the middle of the cross
6. When the point is not in the middle of the cross you must correct it. When the point is under the cross , you must put the centerpons diagonally opposite.
7. When the point is in the middle of the cross. Place the centerpont straight and hit it hard. Now you are ready to drill. When it’s not in the middle you must repeat point 5 and 6 until its ok.