How To Drill Through Cast Iron: 12 Simple Steps

Do you know what cast iron is? It contains 2% carbon in an iron-carbon alloy, and today we are going to show you how to drill through cast iron. Basically, cast iron is brittle and unique compared to aluminum or steel, so you can drill it out without worrying about difficulty.

The drilling angle must be adjusted to be almost neutral when drilling a pilot hole in cast iron. The best option would be a cobalt bit with a 135-degree angle or a titanium nitride drill bit that is gold in color. Use a 1/2-inch cordless drill, which would be an ideal choice. Then simply mark the drilling location, select the appropriate drill bit, hold the drill upright gently, and wipe down the surface with a dry cloth to finish the project.

However, we have more details about the content below. Check out the article to learn how to drill easily with cast iron materials.

Can you drill hole in cast iron?

Cast iron is brittle and not as hard as metals, so you can drill holes into it without much effort. Cast iron can be drilled through with any bit designed for metal. Therefore, you should start the drilling process slowly to avoid overheating and excessive friction, which could harm your drill bit.

What kind of drill bit for cast iron is good?

What kind of drill bit for cast iron is good

We would like to recommend two types of drill bits that are best for drilling cast iron. In addition, other drill bits will work well for drilling holes in cast iron pipes or other materials, but make sure they’re made of HSS or high-speed steel. Conventional drill bits typically cannot cut through metal, but cast irons are not that strong, so you can choose:

  • Bit made of cobalt with a 135° point angle.
  • Titanium nitride bit comes in a golden color.

What Do You Need For Drilling Cast Iron?

What Do You Need For Drilling Cast Iron
  1. First, you’ll need to get a good drill machine or a black oxide drill bit that will perform more effectively, durably, and without leaving a ton of metal particles in the cast iron.
  2. Corded brass drill bits are strongly recommended.
  3. Add some fluid to help the drill bit rotate and penetrate the surface more quickly.
  4. Acquiring a drill bit with a titanium nitride coating to withstand heat and friction is what makes everything easier.
  5. Drill bits made of cobalt steel might be excellent for adding extra hardness.
  6. Remember to use safety gear such as a pair of goggles for your eyes or ears, gloves for your hands, long-sleeved clothes, or clothing made of leather or canvas to prevent slipping or any chance of injury.
  7. A hammer drill can be a good option that takes away the pressure of your drill bit and lets you cut through any surface easily.
  8. An excellent substitute for synthetic oil, hammer drills, and corded brass drill bits is an electronic tool.

Drill Cast Iron – 12 Simple Steps

Using certain drilling techniques can make the cast iron drilling process a lot smoother. However, with the help of any portable drill press and the proper drill bits, you can quickly drill through metal or cast iron. This concept can be used in the case of thick steel plates, aluminum, and sheet metal. Now, let’s discover what steps you should follow when drilling your cast iron material.

  1. Before undertaking the drilling process, grab your safety equipment, including your goggles, hand gloves, and the right driller clothing.
  2. Then, when it’s underneath or on top of something to be drilled into, get a flat piece of scrap wood or sacrificial board.
  3. So, when you decide to drill through cast iron, marking the place is always a wise decision. Using a center punch and a hammer can be great for creating a small hole in the metal where you plan to drill. a little hole where the drill bit’s tip can rest. Until the bit begins to cut the hole, it will help to keep it in line.
  4. Make sure you are using a suitable bit by always checking the size of the hole. Use a bit that is just a little smaller than the screw when you plan to screw into the hole after it.
  5. If the cast iron is a weak component, secure it. Think about using a table vice to support both sides to secure the material.
  6. Due to the high level of friction created during drilling, you will notice that heat is produced. So, just before drilling, apply a few drops of cutting oil, 3-in-1 household oil, or motor oil like 10W-30 or 10W-40 to the metal.
  7. Most drills should be used at a speed of half or less. The bigger the bit, the slower the drill should operate. Cast iron must also be prepped before using a spiral drill bit to drill a hole in it, which requires sanding or grinding the region to ensure the bit can hold the cloth properly.
  8. Keep the drill at low to moderate pressure. Drilling too quickly causes an overheating condition that soon wears down the bits. If you notice smoke, stop drilling, let the bit cool, then restart by adding fresh oil.
  9. Pre-drill the hole with small bits if the diameter is larger than 3/16″. Starting small should be the first decision. By increasing the drill bit in your bit kit to the next size up, you can enlarge the hole. Whenever you require a ½” hole, start with a ⅛” bit and keep going by adding an additional ⅛” inch at a time: ¼”, ⅜”, and ½”.
  10. Basically, shaving to drill a hole is similar to using a knife to peel an apple. Utilize less than 1000 RPM and never go above 3000 RPM. Thus, the gradual procedure with small bits is ideal!
  11. After drilling, smooth down any rough edges with a drill bit that is a little larger in diameter than the hole. The metal shavings can be removed by placing the bit in the hole and gently turning it.
  12. Dry-clean the surface, then use a wet cloth to clean it. Keep in mind that metal debris can hurt, but it also blocks screws from building a strong tie.

Ideal Chart for Drilling Through Cast Iron

Material TypeSurface Velocity (cm/min)SFMFeeding rate per (1 to 3 mm)Revolutions (3 to 6 mm)By bit diameter (6 to 9.5mm)9.5 to 13 mm
Cast iron (soft gray)320075 to 1250.1016 inches0.1651 inches0.2032 inches0.2540 inches
Grey274350 to 1001.2700 inches0.1905 inches0.2286 inches0.2794 inches
Ductile243810 to 200.0762 inches0.1143 inches0.1651 inches0.2032 inches
Malleable167680 to 900.0508 inches0.0762 inches0.1143 inches0.1524 inches

FAQ on How To Drill Through Cast Iron

How do you drill a hole in an iron?

Any metal-boring bit should be used to drill cast iron, but the best ones are cobalt or titanium nitride bits. Furthermore, you do not always need to lubricate and should begin drilling gently before increasing your speed.

What’s the best way to drill through cast iron?

Use a 1/2′′ cordless drill with a shorter range gear, and you should have a speed that is useful. Center punch the area first, then use a drill with a pilot hole that is the same diameter as the drill’s shaft to create the hole. Additionally, you can lubricate to simplify the drilling job.

How do I use basic household tools to cut a one-inch hole in a cast iron oven lid?

You can utilize a titanium or carbide drill bit or hole saw fit in a power drill with bimetal and carbide teeth. Consider using lubricant and moving gently during the process. If you have a steady hand, you can also complete the bore by drilling a 1/4″ pilot hole with a 1″ hole saw using any Dremel-style tool with a grinding wheel.

How can I drill a flat-bottomed, 2-inch recess in cast iron?

Use a moving vise to flatten the bottom of one hole, and then drill a constant series of passes linking the holes with a small offset. Add lubricants and make a minimum cut.

Final Words

So, let’s draw a conclusion now, as we have already discovered everything that you need to know just before drilling through cast iron. So, How To Drill Through Cast Iron? Simple! Pick the right drill bit, start small, mark the spot, drill slowly, use oil or lubricants, and with moderate pressure, drill the metal or cast iron like a pro.

Plus, what kind of drill bits and sizes you should pick has been mentioned above, so we hope next time your drilling job will be much more accurate. Finding the issue about cast iron drilling can also be resolved if you stay connected with us and ask for any further troubleshooting.

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Samuel H. Murphy is DIY expert and Interior Designer. He is also a part time content writer of Capische. He lives in Warren city, Michigan. He test tools like drill, saw, sander, air compressor etc and helps readers to find out the best tools.

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