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.
Other foods that are high in calcium include: 1  Spinach. 2  Kale. 3  Okra. Collards. 4  Soybeans. White beans.  Some fish, like sardines, salmon, perch, and rainbow 1  trout. Foods that are calcium-fortified, such as some orange juice, oatmeal, and breakfast  cereal.
Calcium Calcium is a mineral important for the development of strong teeth and bones and for healthy muscle and nerve function. Food sources include milk, cheese, yogurt, goatâs milk, fortified soya milk, mineral water, ice cream, tinned fish, calcium-fortified tofu, calcium-fortified juices and cereals; and broccoli.