5 Best Drill Bits for Cast Iron

A drill bit is a small piece of element used for drilling through various types of metals. These drill bits may seem similar but each one is manufactured to drill through a specific kind of metal. Even though you can use some of the drill bits for multiple purposes, not all of them can give you satisfactory results when you use them to drill a metal out of their comfort zone. 

Therefore, while dealing with cast iron, it is important to know the best drill bits for cast iron to get proper results after cutting through. You need a drill bit that features- precision, durability, ease, heat resistance, easy storage, and effectiveness.

DIYers pick: Top 5 Best Drill Bits for Cast Iron

You need to look for the right drill-bit material, shank design, and coating according to your preference and your project. But as there’s a large number of drill bits available out there, choosing the right one that is in accordance with your preference can be a tedious process. Therefore, to make this process a bit easier, we are providing you with all the necessary facts you need to know in order to decide.

Top pick Drill Bit

Drill Bits for Cast Iron

COMOWARE: Cobalt Drill Bits for Cast Iron

  • COMOWARE Cobalt Drill Bit Set consists of 13 pieces.
  • It is highly durable.
  • The drill is remarkable abrasion and heat resistant. 
  • A precise split point of 135 degrees is available.
  • 5% cobalt helps the drill bit with its performance.
  • It comes with a bit holder for effortless storing. 

COMOWARE Cobalt Drill Bit is one of the best drill bit for cast iron. If you are looking for a heat-resistant drill bit set that offers you maximum control while drilling through cast iron, then this drill bit set is the one for you. This drill bit is capable of making more than two hundred holes effortlessly. It is highly recommended for drilling hard metals with ease as it is made of M35 cobalt HSS. Because of this material, it also has a greater life expectancy than some other drill bits. 

This drill bit also has a unique feature that boosts up the cutting speed by preventing walking and clearing particles and chips faster. This is possible because of the precise split point of 135 degrees and the twist design. This design also promotes edge chipping without having to face any trouble. Lastly, you can easily store this drill bit set as it comes with a drill-bit holder. Size index is also printed on the holder for better organization.

  • COMOWARE Cobalt Drill Bit Set offers great efficiency. It is highly suitable for drilling through hard metals. It has exceptional wear resistance and heat resistance. This drill has an excellent cutting speed. The bit holder that it comes with helps you store the 13 pieces without facing any trouble.

  • Even though this bit set claims to be able to drill through the hardest metals, it tends to lose its sharpness while dealing with thick metals. It cannot handle the pressure that well. The durability is often compromised due to heavy drilling.

Cast Iron Drill Bit

Cobalt Cast Iron Drill Bits

Metric M42: 8% Cobalt Cast Iron Drill Bits 

  • Metric M42 8% Cobalt Twist drill bit provides great chip, wear, and heat resistance.
  • It offers great versatility due to its 3-step design.
  • The drill bit runs faster and offers more holes than others. 
  • A split point of 135 degrees is available for easy drilling.
  • The set consists of 19-piece drill bits.
  • It can operate for a long time without damage.
  • Change of speed is possible and can be turned to maximum. 

Metric M42 8% Cobalt Twist drill bit is one of the most well-known drill bits for cast iron. It has so many good qualities and features that people tend to overlook the high price it comes in. This drill bit is made of 8% cobalt steel and is capable of drilling through materials like cast iron at a very high speed and with great efficiency. It is highly chip, wear, and heat resistant. You can easily boost up the speed 5 times faster and yet operate it without overheating it or causing any damage. 

The design of this drill is a combination of three layers. These layers not only make the drill bit highly versatile but also make it tough enough to drill through without breaking the drill tip. Therefore, this drill bit is also has a great life expectancy. 

  • Metric M42 8% Cobalt Twist drill bit features a three-step design that lets you drill through hard materials easily. You can operate it for hours without causing any harm. You can also tune the speed to the maximum without damaging it. It doesn’t overheat easily and helps you drill a larger number of holes quickly and precisely.

  • The one and only drawback of the Metric M42 8% Cobalt Twist drill bit is the price it comes in. compared to all the other drill bits, it is very costly.

Best Budget

Best Budget Drill Bit for Cast Iron

Amoolo 1/4″: Best Budget Drill Bit for Cast Iron

  • Amoolo ¼-inch cobalt drill bit is made of M35 cobalt for heat resistance and durability.
  • Power drill attachment is easier due to the 69.85 mm flute length.
  • High-speed steel construction improves the overall performance.
  • A split point of 135 degrees is available for easier metal drilling.
  • The drill can quickly clear particles and reduces friction.
  • It comes with a set of 10 pieces of bits.
  • The drill bit has the ability to fit most power drills.

If you are searching for a cast iron drill bit that is budget-friendly as well as provides high performance while maintaining its cool, the Amoolo ¼-inch cobalt drill bit is the one for you. It is one of the top drill bits for cast iron.

This drill bit is preferable for most cases because the bits can be easily fitted with a power drill and most power drills have the exact chuck size as this drill bit size. It has a fully-ground spiral-groove design that allows it to quickly clear out particles and maintain cool by reducing friction. This drill bit make your drilling more precise as it features a split point of 135 degrees. 

  • You can easily attach Amoolo ¼-inch cobalt drill bit to any power drill. It is highly durable and provides great performance. You can store it very easily and also carry it with you as it’s portable. The price is comparatively low and it comes with a warranty of 90 days.

  • Amoolo ¼-inch cobalt drill bit is not at all versatile. You can not use it on carbon steel or ceramic materials. Even if you do, the result won’t be satisfactory. Another drawback of this drill bit is its tendency to overheat. You may need to water it every now and then to cool it down.

Premium Pick

Best Cast Iron Drill Bit 

DEWALT: Best Cast Iron Drill Bit 

  • DEWALT Titanium Drill Bit can drill through variable surfaces.
  • The drill set consists of 21 drill bit pieces.
  • The pointed tip provides smooth edges holes.
  • The storage system allows you to store drill bits without taking up much space.
  • The bit-bar design promotes the personalized placement of drill bits and effortless removal. 
  • The set comes with a clear lid that makes the internal contents visible. 
  • Secure closing is possible due to the presence of a clip latch. 

DEWALT titanium drill bit is one of the top drill bits for cast iron. If you are looking for a drill bit that can provide clear, burr-free holes on several types of materials, you should undoubtedly consider this one. It comes in a set of 21-bit pieces. It is a drill bit of great efficiency and speed. 

The web taper feature that it comes with increases rigidity over different metals and increases both speed and ease while drilling through metals. It also has a bit-bar design that allows you to remove the drill bits more easily. This drill bit set comes with a storage box that can be personalised according to the user’s preference. This bit drill also features a clip latch that increases the safety of the operation. 

  • You should know that DEWALT Titanium Drill Bit is a multi-functional bit set. It comes with a proper storage facility. You can use it for drilling through all kinds of metals quickly and with proper safety. It provides you burr-free, clear holes no matter what the thickness is.

  • DEWALT titanium drill bit lacks two of the most important features. One is the ability to withstand pressure and the other is the capability of remaining cool. This drill bit tends to overheat easily and its ¼ inch bit cannot endure pressure doesn’t matter how minor it is.

Customer Choice

Twist Drill Bits for Cast Iron

Hymnorq Metric M35: Twist Drill Bits for Cast Iron

  • Hymnorq metric drill bit is made of M35 cobalt steel.
  • 12 times better lifespan than HSS drill bits.
  • The bit has a solid exterior for drilling stern metals.
  • Bits can stay on irregular metal surfaces due to self-centering.
  • Straight shank offers proper centering and firm holding.
  • A quick-cut point of 135 degrees is available.
  • The drill set consists of 13 pieces.
  • It provides 67 plus firmness. 

Hymnorq metric drill bit is one of the industry-leading cast iron drill bits that is quite famous for its exceptional features that too at a comparatively low price. It is made of 5% cobalt with steel alloy. It has the admirable heat-resisting capability, hardness, life expectancy, and speed of cutting through metals. The heavy-duty construction and firm holding with proper centering allow the drill bits to break through hard metals quickly and effortlessly without putting on too much pressure. 

This drill bit is very versatile as it can stay on both even and uneven surfaces. As a result, you can use it for drilling all sorts of metals and not care about the hardness. Another feature of this drill bit is that you can adjust the RPM and thus increase its efficiency. 

  • Hymnorq metric drill bit is highly durable due to its solid exterior. You can use it for drilling both hard and soft metals. It is highly heat resistant. It provides proper centering. It can cut through metal faster than most other drill bits. Provides excellent performance on even as well as uneven surfaces. You can easily download the user guide for smoothly operating it.

  • The only problem with the Hymnorq Metric M35 Cobalt Steel Extremely Heat Resistant Twist Drill Bits with Straight Shank is the price it comes in. it is highly costly in comparison to the other drill bits available out there.

How to drill into cast iron?

Even though drilling through cast iron is an easy task compared to drilling through other materials, because of their fragility, you still need to follow a guideline to ensure fast and effortless operation. The guideline of the process is given below-

  1. At first, you need to lubricate the drill bits because it helps to prevent overheating. However, if you only need to make 1 or 2 holes then lubricating the bits is quite unnecessary and unreasonably messy. 
  2. Making sure that the drill bit you are using is in fact the right one corresponding to the drill is necessary. So, you need to check the hole size and ensure that. Also if you are using a screw, ensure that the screw is relatively larger than the bit.
  3. You need to mark the point where you want to drill. You can use a hammer and a center punch to do so. This way you won’t go off course and the mark will lead the drill bit. 
  4. In case your cast iron isn’t attached to a fixed body, brace it in place so that it doesn’t move to another point.
  5. Now that you have set the drill at the right position, placing it adjacent to the mark, you need to gradually pull the trigger. After drilling, drag the drill backward and forward to get rid of metal debris.
  6. Finally, you need to use a dry cloth to clear off the surface, then do the same with a wet cloth. And lastly, repeat it with a dry cloth again. Clean the inside of the hole as well so that there’s no metal debris as it may cause harm. 

Factors to pick the Best Drill Bits for Cast Iron

As mentioned earlier, drill bits are quite similar yet each one is only capable of drilling through a specific material. Therefore, you need to follow a guideline to understand what kind of drill bit for cast iron to look for. 

Drill-bit Material

The material of a bit influences the effectiveness of it being able to drill through various metals. A drill bit can be made of carbide, cobalt, or high-speed steel. Drill bits for cast iron either need to be made of cobalt or high-speed steel. Because only by using these two materials you can achieve clean and precise holes when the metal is cast iron. 

Shank Design

This is another important factor to consider. The bit’s non-drilling edge is known as the shank. It’s fitted into the chuck of the drill. So, the chuck size and shank size should be a match because otherwise, you won’t be able to fit the bit properly. And without fitting it properly, the operation may hamper, and also safety concerns may occur. There are mainly three shank sizes- ½ inch, ⅜ inch, and ¼ inch. 

There are also two types of shank designs to consider. One is a no-spin shank and the other one is a hex shank. The latter one has 6 sides that provide great support and steadiness while drilling through hard materials. And the no-spin shank design prevents the bit from falling assuring your safety. So, depending on your requirement, you’ll need to decide which design is more suitable for you. 


This kind of drill bit is generally coated with black oxide or titanium. As a result, it is possible to prevent the drill bit from overheating as the coating decreases resistance and thus increases speed. So, while buying your drill bit, make sure the coating is present otherwise you may face problems while operating. 

Safety Tips for Drilling through Cast Iron

Safety is vital whenever drilling is involved. Even though nowadays drills come with safety guards, you should still follow the below-mentioned tips for additional security for cast iron drill bit-

  • Lubricate your drill bits if you are using the bits frequently to prevent overheating.
  • Speed is proportional to friction. So, at first, make sure the speed is at a low level. Because it allows drilling without causing overheat. 
  • If you are using step bits for making large holes, keep an eye on the speed setting so that you don’t bore too large of a hole. 
  • Always use a rug to wipe out excess oil or metal debris. Never use your clothes to do so because the sharpened debris may cause injuries. 
  • Remember to indent your surface before operating. Because once you have the drill in your hand, confusion about the point may cause harm. 
  • Before drilling, make sure to check the material’s width with a leveler or a ruler. Without knowing the width you can easily cause damage. 

FAQs on Best Drill Bits for Cast Iron

Can Cast Iron be drilled and tapped?

The answer to this question is yes, cast iron can be drilled and tapped. In fact, sometimes it becomes important to tap the hole after drilling so that the drill tip doesn’t break down. Cast iron has two side products- chips and metals. While drilling through cast iron, these products, however, how small they are, have the strength to break the drill tip. Therefore, after drilling the cast iron, tap the hole to ensure that the drill tip hasn’t broken. 

Is cobalt or titanium drill bits better?

The answer to this question depends upon which material you plan on drilling. Because despite their similarities, each drill bit is designed for drilling through a specific material. If you are dealing with ferrous metals like- cast iron, then cobalt drill bits are the right choice for you. Because these drill bits work better while drilling ferrous materials. However, if you need a drill bit for drilling soft materials like aluminum, then a titanium drill is the better choice.

Will a Sawzall cut cast iron pipe?

A Sawzall is an alternating saw. You can use this tool to cut through cast iron pipes efficiently because it is designed to deal with hard materials like cast iron, wood, PVC, etc. If you have a Sawzall already, all you require is a cast iron blade. It is a very versatile and powerful tool that can effortlessly and precisely cut through cast iron pipes and produce minimum dust particles. 

What’s the best way to cut cast iron?

As there are several ways of cutting through cast iron, choosing the best way is necessary to minimize human effort, time, and also to increase precision. Even though the blade of the diamond saw is more powerful than drill bits, it is more accurate and trouble-free to deal with, and it clears out dust particles as well. Therefore, drill bits are the most preferred way for drilling through cast iron. 

Take the Best Drill Bits for Cast Iron

In this article, we aimed to provide you all the necessary information regarding the best drill bits for cast iron. We discussed the features, advantages, and disadvantages of the top 5 cast iron drill bits. We have also provided you with a guideline for turning a drill into cast iron in case that is the information you need.

But as there are other drill bit options available out there, we also added a buying guide to help you evaluate them as well based on their features. We hope you found the reviews and the additional pieces of information helpful for choosing the accurate drill bit that gives you your desired result. 

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Sam Morgan is a professional interior designer and part-time content writer of Drill Villa. He has done hundreds of major projects and sharing his experience with you. He is a tools lover like drill, drill press, drivers, wrench etc. He used and tested thousands of tools and knows which perform better.

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