Looking for the Best Drill Bit for Hardened Steel Bolt? Let’s Get After It…

For the uninitiated, hardened steel is produced through a four-step process and with carbon steel at high temperatures. As the name indicates, bolts that are made of hardened steel are extremely durable and are used in a bunch of industries. Also, hardened steel bolts are extremely resistant to wear and tear, making these an ideal choice for diverse applications. When you want to find the best drill bit for hardened steel bolt, you have to find a product that’s designed to work for material as durable as this kind of steel. In this guide, we have listed the basics and a few products that you can consider.

In a hurry? WE GET IT, dudes. See our top pick below!

Migiwata Metric M35 Twist Drill Bits with Straight Shank Set.

Top pick

Migiwata Metric drill bits


Migiwata brings this set, which includes drill bits that are made of M35 cobalt steel with added molybdenum and cobalt. The product is designed to be heat resistant, and no… Read More on Amazon


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Reviewing top five products

Here’s our list of five drill bits that work perfectly for hardened steel bolts.

    1. Migiwata Metric M35 Twist Drill Bits with Straight Shank Set. Migiwata brings this set, which includes drill bits that are made of M35 cobalt steel with added molybdenum and cobalt. The product is designed to be heat resistant, and no center punch is required, as the 135° Quick-Cut points are self-centering and work without a lot of pressure. The set contains 13 pieces of M35 cobalt steel twist drill bits, and you can check the product description for measurements. This product is specifically ideal for hard metals. In case you are not happy, the brand also offers a full refund or replacement.
    2. Irwin Tools 3018002 Cobalt M-35 Metal Index Drill Bit Set. This set comes from Irwin Tools and is among the best-rated ones in the market. There are 29 pieces included in the package with 135° Quick-Cut points for minimizing the use of pressure. The product is higher heat & abrasion resistant and is ideal for both commercial and residential use.
    3. DEWALT DW1354 14-Piece Titanium Drill Bit Set. DEWALT brings this drill bit set that’s great for extreme use and for hardened steel bolts. If you want more, DEWALT also has sets with 40, 45 and 80 pieces and at quite affordable prices. With titanium pilot point, these drill bits are meant to last, while the tapered web prevents breaking. The brand offers a 30-Day Money Back Guarantee on the product, which is a plus.
    4. Titanium Drill Bit Set from Mastercraft. If you are looking for a big kit that can work for all kinds of hardened steel bolts, this product from Mastercraft is a great steal. The drill bits measure from 1/16″ up to 1/2″ bits and are meant to be designed on other products or materials such as plastics and glass. Titanium coated HSS ensures that these drill bits are durable, as much as by 6 times, compared to conventional bits. The whole set comes in a heavy-duty storage case.
    5. Impact Drill Bit Set for Hardened Metal. As the name implies, this product, which is from Proffi, is designed for hardened metal and includes seven pieces of high-speed steel bits. Compared to HSS drill bits, these are 25 times stronger and are ideal for both industrial and professional use. The product is made in Europe and of M2 HSS, which has procured from three big vendors. The company ensures manual inspection of all sets before being sold.
    6. Stroton Metric M42 8% Cobalt Twist Drill Bits Set – This product is made of premium M42 8% cobalt steel, which comes with long tool life. You can expect this cobalt drill bit to run faster by three to five times than other counterparts in the market. As you can produce many holes with this tool, your cost per hole will be the lowest while using this product. As it comes with a sharp bit edge, it can cut through metal in long strips instead of grinding through the material slowly. It can ideally be used on hardwood, plastic, aluminum, stainless steel, and other hard metals.

Things to know

There are five different levels when it comes to selecting HSS drill bits. These are T1, M2, M7, M35 and M42. M42 contains 8% cobalt, while M35 contains 5% cobalt. M42 rating is usually desirable for hardened steel, and it is important to consider some of the other aspects, such as the brand and warranty on the product. No matter whether you are using drill bits for personal use or professional needs, it makes sense to go for a product that’s meant to last and is durable, because eventually, you would be working with hardened steel bolts. Some brands are obviously better than the others, and you can expect to get a warranty or a replacement option on the product.

To sum up things, make sure to choose drill bits that are made of cobalt or a better material, check the brand, and if possible, go for a set that contains more sizes of drill bits. Most of the available sets are available online with a box, which is a big advantage because storing your drill bits will be easier.


How does the rating system for HSS drill bits work?

In our last section, we covered the importance of knowing the different levels of HSS drill bits. It’s important to understand what each of the drill bit levels is meant to illustrate. The ratings that you see are meant to give you an idea of the composition of the drill bits, and also help you pick the right tool for the job.

Drill bits in this system are rated by the Unified Numbering System, which measures their chemical composition. Though there’s a lot more to this than what we’re going to go into, we’re going to explain the bare basics:


  • Most HSS drill bits are rated as either molybdenum-based, tungsten-based, or hybrid. Molybdenum-based drill bits have high levels of molybdenum and are signified by a code like M45 or M7. Tungsten-based bits are labeled with a T, such as T1 or T7. Mixtures start with T113.

  • There are 7 tungsten types and 17 molybdenum types that are widely recognized. You will most likely use an M45 or a T1 for most of your projects.

  • M2 is the standard for most projects that involve HSS drill bits. M35 is a close second, though it’s pricier. This is because M35 has cobalt and is known for being longer lasting.

  • You should try to make sure that the drill bits you get work with the steel bolts that you intend to use in your product. This is why drill bits that are rated as M2 or M35 tend to be so popular. With that said, higher-rated drill bits will always work with softer metals.


How many drill bits should you get?

Honestly, this all depends on how much you’re doing with the steel bolts in question. If you are just getting these bits for a one-time project, then there’s no reason to go crazy with 90-piece bit kits. Just get the smallest pack you can find with the drill bits of the size that you need.

On the other hand, if you’re a professional construction worker or are putting together your own woodworking area, you might want to go for a more complete set. With that said, it’s never a bad idea to get more bits than you think you’ll need. They’re remarkably handy.


Does price impact the quality of drill bits?

Like with all other tools, there’s a general belief that you get what you pay for. However, there’s always a caveat. In this case, price tends to be a good teller of quality, but only to a certain point.

What you really should look for is the brand of drill bits that you’re getting. Certain brands, like Milwaukee or DEWALT, are known for having solid builds and standing by their work. This means you get better reliability and a more trustworthy set of tools.


What do the angle ratings on drill bits mean?

There are two main angle ratings that you will find on drill bits — 118 degrees and 135 degrees.

118 is the standard drill bit angle, and it’s the most widely used. It’s reliable and if you’re the type of craftsman who likes to get used to a “feel” of a tool, you will enjoy these cause they’ve been around forever.

135 is a “self-centering” drill bit, and it’s fairly new on the market. This is an upgrade that lets your drills spin faster and


How long should drill bits last?

This is a pretty loaded question, because a lot of what you will be able to accomplish with these bits will depend on how often you use them and how well you keep them. If you are the type of person to leave your tools in a puddle of spilled soda overnight, you’ll have a limited run with any drill bits you have.

Most drill bits that are kept properly should last between 20 to 40 holes, as long as they’re top quality. If you notice your drill bits getting frayed, dull, or chipped, it’s important to replace them immediately. Most users can get a good two to three weeks of steady use before they need to be switched.


What is the strongest material for drill bits?

If you want to get a seriously powerful drill bit, then opt for carbide. Carbide is considered to be the strongest material that drill bits can be made from, and drill bits made with it are typically used in high-grade, commercial-level projects.

However, there’s a caveat with carbide. Carbide can be brittle and can actually be too much for your drill to handle. That’s why it’s not advisable for drill presses or even hand drills. If you want to get the strongest for a more standard project, opt for cobalt instead.

Cobalt is generally considered to be a nice upgrade from HSS (high speed steel) drill bits. Cobalt’s makeup is stronger than regular HSS, but also offers enough “give” to make your work easier.


Are drill bits interchangeable between brands?

This all depends on the purpose and what you mean by “interchangeable.” If you’re asking if drill bits from Brand A will fit into a kit from Brand B, then yes, almost all (if not all) drill bits are going to be interchangeable. This is because manufacturers understand how chaotic workspaces can get and don’t want to force their workers to run to Home Depot for a matching brand.

If you are talking about quality being equal across the board, things get stickier. If you get off-brand drill bits for your drill kit, you generally should be alright as long as you’re using them on wood or another light material. It’s best to choose drill bits from a well-known, accepted brand if you want to use them on high-grade steel.

It’s considered to be good practice to use drill bits on a drill that’s from the same brand. Whether or not it makes a huge difference, though, remains to be seen. It’s up to you to determine whether it’s a good move for you.


Frequently Asked Questions


1. What should be the qualities of drill bit for hardened steel bolt? 

The drill bit for hardened steel bolts should be made up of high-speed steel. It should also be extremely sturdy with an extra coating of titanium nitride or cobalt. With a high-quality drill bit, you don’t get the thread damaged. 


2. What kind of drill bits is strongest?

Drill bits made up of tungsten carbide are much stronger. These hold a better rank as compared to other metals available due to features like sturdiness, toughness, durability, and brittleness. Also, drill bits with carbide drill fast and do not chip. For other options available, you can also use drill bits made of titanium nitride. 


3. Can hardened bolts be drilled? 

Yes! If you are unable to loosen a tight bolt, then you can surely drill it with a strong and extremely sturdy drill bit. Ideally, locksmiths find drill bits with carbide tips suitable for drilling out the hardened bolts, taps, studs, etcetera. They prefer carbide-tipped ones because they don’t chip off and dissipate heat soon. 


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