Can I Drill Through Cast Iron?

Cast iron is a sturdy metal that’s used in all sorts of applications. If you need to attach something to it or you have to release pressure, you could be worried about breaking a drill bit. However, it’s not as challenging as you might think.

You can drill a hole through cast iron with any drill bit for metal. Cast iron is much more brittle than other metals and is easy to drill into. Start drilling slowly to prevent overheating and excess friction that can damage your drill bit.

Can I Drill Through Cast Iron?

Before we get into the guide of how you’re supposed to drill through cast iron properly, let’s check out what items you need.

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READ: Do You Need A Special Bit To Drill Through Stainless Steel?

What Do You Need For Drilling Cast Iron?

First and foremost you will need a drill. If you don’t own one go and check my article on top cordless drills.

You can use almost any drill bit to cut through cast iron, including the cheap ones that you find in the discount aisle.

Since cast iron doesn’t resist the twisting motion of a bit, you’ll be able to drill right through it. The only issue that you’ll be dealing with is the debris.

If you want to make the task even more manageable, reach for a black oxide drill bit. They’re durable, and you won’t have tons of metal shavings stuck in the cast iron when you’re done.

You can also try out a cobalt steel drill bit, which provides additional toughness. It’s nearly impossible to break a cobalt steel twist bit on cast iron.

Either of these substances will cut right through the metal without becoming dull too quickly.

You can even take it a step further by getting a drill bit that’s coated with titanium nitride to resist heat and friction. Even if the cast isn’t hot, the friction will build heat quickly. It’s believed that drill bits with a TiN coating last up to six times longer than the average bit.

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It also goes without saying that you should wear safety gear. Pick out a pair of goggles that protect your eyes and ears, as well as your temples. Don’t forget to get a durable pair of work gloves as well. You should pick a pair made out of leather or canvas to prevent slippage and potential harm.

Finally, consider wearing long sleeve clothing. Denim jeans and a work jacket will be more than enough to keep yourself from getting hurt. Even if you’re a professional, safety always comes first.

Alright! Without further ado, let’s jump into the step-by-step guide below.

How to Drill Through Cast Iron

Before you begin drilling, you’ll need to prep all of your tools to cut through the material easily.

Start by applying lubricant to your drill bits before using them. If you’re only drilling one or two holes, you don’t need to worry about lubing them.

However, anything more than that calls for cutting fluid. You can get a small bottle at a good price on Amazon. If you are doing a lot of drilling into metal I recommend you to get the 1 Gallon bottle of cutting fluid. Cutting fluid not only saves your bits but also prevents metal shavings from flying.

Here’s a simple guide to get it all done relatively quickly:

  1. Create a dimple or an indent wherever you intend to drill. It’s always a good idea to mark the location, so you don’t go off course, but the indent also helps to guide the drill bit. Use a center punch and a hammer to make your marks.
  2. Attach the correct drill bit to your drill. Always check the size of the hole and make sure that you’re using the corresponding bit. If you’re following the hole with a screw, you need to use a bit that’s slightly small than the screw. The difference will allow the screw to hold onto the leftover metal, creating a secure bond.
  3. Brace the cast iron in place if it’s a loose piece. If it’s connected to an immovable object, it’ll already be braced for you. Consider a table vice to hold both sides of the material rather than only one side.
  4. Holding the drill upright, begin to slowly pull the trigger and place it against the indent that you created. Don’t be afraid to start with a smaller bit if you’re worried about making a mistake. It’s always better to do it a few times rather than mess the whole thing up.
  5. Once you’ve made the hole successfully, hold the trigger down, and slowly pull the drill back and forth in it. This process will deburr the hole, which means that it removes the metal debris that was left behind.
  6. Wipe down the surface with a dry cloth, then use a wet cloth, and repeat once more with the dry cloth. Don’t forget to get the inside of the hole, even if it’s thin. Metal debris can cause harm, but it also prevents screws from achieving a secure bond.

That’s all there is to it!

Again, this material never puts up much of an issue. It’s malleable if you use the drill bits mentioned at the beginning of this section.

To finish off, let’s review a few tips to help you get the job done well.

Additional Tips and Advice

Safety is essential, but so is convenience. Fortunately, you can get the best of both worlds by following these suggestions. Give them a try and figure out what gives you the results that you’re searching for.

  • Feel free to use the extra cutting fluid as you’re drilling. When you’re using a drill bit regularly, it starts to warm up. Wipe away the debris and reapply oil if you’re using it for long periods of time.
  • Start with a slow speed setting. More speed = more friction, which means more heat. Slower drilling allows you to go through cast iron without dulling out your bits or over-heating your drill. You should never exceed 3000 RPM, though less than 1000 RPM is doable.
  • Step bits are handy if you’re trying to drill a large hole. If you use one, make sure that you don’t go too fast; Otherwise, you could bore a hole that’s far too big.
  • Keep an old rag nearby whenever you use a drill bit on any type of metal. You’ll have to wipe up the excess cutting fluid and the metal shavings. Wiping it on your pants or shirt (as many DIYers have done) can cause injuries from the sharp debris.
  • Always mark your surface with a permanent marker beforehand. This indicator will give you a clear vision of where you want to start, rather than leaving you to guess where you should drill.
  • Don’t forget to check the width of the material that you’re drilling into! If you go too far, you could damage anything behind it. Keep a ruler and a leveler in your tool kit at all times to prevent those issues.
  • Finally, never drill into loose cast iron. Vices are an absolute necessity if it’s not attached to a surface already.


Drilling cast iron is easy. It is a brittle metal that doesn’t have much debris.

The aforementioned heat-resistance and toughness make this material a top contender for at-home projects, so use it and drill into it without worrying about it breaking.

Here are a few key takeaways from this post:

  • You can drill into cast iron by using any type of drill bit for metal.
  • Don’t forget to use cutting fluid if you’re drilling many holes.
  • Always use a clamp or vice when you’re drilling into any surface.
  • Wear safety goggles, gloves, and clothing.
  • Remember to mark the spot with a marker followed by a center punch and a hammer.
  • Start drilling slowly to prevent excess friction, heat, and dulling.

Cheers, tools owners!

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Hi there! My name is Jack and I write for ToolsOwner. I have a passion for everything related to tools and DIY projects around the house. You often find me in my workshop working on new projects.