Best Drill Bits for Hardened Steel Reviews 2017

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What makes the top rated drill bits for hardened steel? If you have ever attempted drilling through hardened steel, or metal, then you know just how tough that can be. Using an ordinary drill bit designed for normal metal materials will not work, and in fact will ruin that bit for other uses.

The perfect drill for taking on hardened steel is a “Cobalt HSS” drill bit which has been specifically designed for this purpose.

Understanding Hardened Steel

I always find that when I understand how something is made, that it is easier to understand how you can work with it. This includes how to drill it. Hardened steel will take an ordinary steel that is high in carbon content and put it through the processes of quenching and then tempering. To harden steel extremely high temperatures are used, and that type of steel must have a lot of carbon in it to begin with.

All hardened steels go through a four step process which I will not bore you with here. It is important to note that the carbon steel is heated to high temperatures which hardens the steel.  It is then dipped into cold water, pretty much in the way you would see a blacksmith working, but that makes it brittle.

The tempering process then reduces how brittle the steel becomes and the net result is you are left with a pretty tough steel product.

I have included a video below on how to check if the steel you are going to be drilling is actually made from hardened steel.

Video On How To Check If Steel Is Hardened or Not

Uses of Hardened Steel

Hardened steel is used for objects that are subject to high levels of force or abuse such as cranes, car parts, trucks, hand tools, guns, and knives to name but a few. Compared to ordinary steel, hardened steel is much more durable, more resistant to wear and tear and perfect material for all types of heavy duty applications.

Top 3 Drill Bits For Hardened Steel

So at least we now know what we are trying to drill through. If you have never done this before, then you are in for a pretty tough piece of drilling. Attempting to do this with any of the standard drill bits that you get will be impossible. If you try to use any of those, then not only will you be wasting your time, but the hardened steel will ruin those bits for use on other types of softer metals.

You need a drill bit that has been designed to cut its way through the hardened steel and a cobalt drill is the correct type. I have listed below the best 3 cobalt drill bits available on the market today. Just before you have a look at them I think it is important to understand how HSS drill bits are actually graded.

Cobalt Drill Bits

There are basically 5 different levels of HSS drill bits

  • T1
  • M2
  • M7
  • M35 – 5% cobalt
  • M42 – 8% cobalt

So for drilling through hardened steel you would want bits with an M42 rating

Bosch CO18 18-Piece Cobalt Twist Drill Set

The logic is that to drill through any material the drill bit that you are using has to be made of a material that is harder, than the material you are trying to drill through. In addition to this, very high temperatures will be created when you perform any kind of drilling task. With the Bosch CO18 drill bits they can handle temperatures of up to 1,100 degrees Fahrenheit so you know they are ideal for drilling through the toughest of steels.

In this set you get a total of 18 drill bits, starting at 1/16″ and all the way up to a 1/2″ bit size which are all contained in a plastic case for storage. for the most common drill size holes you get 2 drill bits of each size and these are the 1?162, 5/64″, 7/64″, 1/8″  You also get 1 each of 3/32, 9/64, 5/32, 11/64, 3/16, 7/32, 1/4, 5/16, 3/8, 1/2 These drill bits will fit on to any standard 1/4″ to 1/2″ chuck.

They are very sharp and more importantly, the stay sharp. They get really top reviews and are a really good investment.

Neiko Super-Hard 13 Pcs Cobalt Drill Bit Set

My second choice are considerably cheaper and yet these will also handle hardened steel. You get 13 drill bits here instead of the 18 in the Bosch set above. These also come in a nice looking metal box. In my opinion these are not the same high quality as the Bosch ones above and I think that is reflected in the price. At the end of the day these are under $10 and will get the job done for you.

They are in my opinion though only suited for that. So if you are someone who will be using drill bits a lot, better to spend the extra money and get a really good set. I have simply included these because of the price but they contain very low amounts of cobalt so will not last that long.

Irwin Industrial Tools 63221 Cobalt Metal Index Drill Bit Set, 21-Piece

If you can afford these cobalt drills then these will last you for a very long time. These are very high quality and will last a long time. Buying cheap drill bits is never a good idea in my honest opinion. I have done that in the past and the reality is that after a few uses you may as well throw them away as they become blunt and useless for drilling.

I think you are better with one good set that you can reply on to get the job done. The problem is of course you will have to pay to get that type of quality. I guess therefore it depends on how much use they are going to get and how much you really need or depend on them. This set gives you 21 high quality cobalt bits and are M42 rated with a 5% cobalt content.

Enda McLarnon

Enda McLarnon is now retired and is now enjoying writing about his love of power tools. All types of these tools are now available and they make working on projects and DIY jobs around the home a great deal of fun