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.
Fun fact: Calcium is the most abundant mineral in the body, and is found naturally in a wide variety of foods and beverages and added to many others! (Hellooo orange juice.) But whether lactose-intolerant or sick of wine and cheese parties, thereâs no need to rely only on dairy products for that daily dose of calcium.