Go to a hardware store and get the size bit you need that is made for metal. Most cast iron isn't really hard unless it is white cast iron. If the hole is over 3/16, pre-drill it with a small bit first. It might be a good idea to use some cutting oil to.
For more info, see the section on calcium absorption. High calcium foods include dark leafy greens, cheese, low-fat milk and yogurt, bok choy, fortified tofu, okra, broccoli, green beans, almonds, and fish canned with their bones. The daily value (DV) for calcium is 1000mg.
Good sources of calcium include: 1  milk, cheese and other dairy foods. 2  green leafy vegetables â such as broccoli, cabbage and okra, but not spinach.3  soya beans. 4  tofu. 5  soya drinks with added calcium. 6  nuts.7  bread and anything made with fortified flour. 8  fish where you eat the bones â such as sardines and pilchards.ood sources of calcium include: 1  milk, cheese and other dairy foods. 2  green leafy vegetables â such as broccoli, cabbage and okra, but not spinach. 3  soya beans. 4  tofu. 5  soya drinks with added calcium. 6  nuts. 7  bread and anything made with fortified flour.