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.
Goat's milk and cow's milk both are rich in calcium. Two other good sources of calcium are mozzarella cheese and blackstrap molasses. Other good sources of calcium are oats, wheat durum, pistachios, hazelnuts, Brazil nuts, cheddar cheese, cheese cream, eggs, caviar, pollock, low fat cream, pollock, and perch.alcium Rich Fruits and Vegetables. Everybody knows that milk and milk products are a good source of calcium. But, there are also many calcium rich fruits and vegetables which make an excellent source of this mineral.