How to Drill through Hardened Steel

Drilling into hardened steel isn’t as simple as wood due to the extreme toughness of the material. So along with learning how to drill through hardened steel, you have to apply the appropriate tools to penetrate the hardened steel. Even the safety measurement is also vital as slippage, breaking down the drill bit and the steel particles can easily cause serious injury.

Therefore, we have briefly discussed a helpful process of drilling into hardened steel that will allow you to create larger holes efficiently. We also mention all the required tools and safety gear to complete the task conveniently.

Guides to Drill through Hardened Steel

Tools require:

  • Workbench
  • Plastic or metal c clamps
  • Permanent marker or pencil
  • A hammer
  • A center punch
  • A black oxide drill bit or cobalt steel drill bit.
  • Drill
  • Drill press (optional)
  • 30 weight oil, spray bottle with water or lubricant oil
  • Protective goggles
  • Closed-toe shoes
  • Long-sleeved shirt
  • A brush or a shop cloth
  • Medium or heavy metal rasp

Secure the hardened Steel

Use plastic or metal c clamps to tighten the steel. Firstly place the hardened steel on a workbench and then secure it using clamps so it can move while drilling. If you don’t firmly tighten the clamps, the steel will spin and can injure you. But if the working piece is heavier steel, you don’t need to secure it. Despite if the surface of the steel is painted, use stir sticks between the steel and the clamp to prevent scratching.

Mark the exact spot

Identify the place you wish to create a hole in the hardened steel using a permanent marker or pencil. You should also consider the drill bit diameter while marking the spot and locating the center of the hole by making a dot.

Make a dent

When it comes to drilling through a hardened hole, creating a dent before the real drilling can make the task quite efficient. So use a hammer and a center punch to create a divot in the hardened steel. Firstly, place the center punch’s tip on the marked spot and hit the punch gently with a hammer to create a little dent. This small dent will greatly help the slipping of the drilling and offer a hole at the exact spot. You can also apply a nail instead of a center punch.

Choose the drill bit

If you need to drill only a few holes into the hardened steel, a typical HSS drill bit will be an acceptable option. Conversely, a black oxide drill bit or cobalt drill bit is preferable for drilling plenty of holes into hardened steel. But make sure the drill bit you are using a completely sharp. Remember, drill bits are usually in a set of multiple sizes, and these can be sharpened if they become dull.

Start with a smaller size bit

When dealing with hardened steel, it’s better to use a half-diameter drill bit like the actual size. The reason is that smaller bits generally put less force on the steel and allow you to create larger holes efficiently later on. So if you need to create a 1⁄2 inch hole, in the first step, create a 1⁄4 inch hole.

A Drill Press is better for a larger piece of Hardened Steel

A drill press is a heavy-duty DIY tool that ensures a straight hole with improved accuracy, whether it is a soft or hard material. Since securing a larger piece of hardened steel will be tough on a workbench, a drill press will make the task quite easier. You can use a bench drill press and a floor drill press. The first option comes in a compact design, while the second model is suitable for frequent use.

Prepare the lubricant

You can use a range of items as lubricants, including, 30 weight oil, spray bottles with water, and lubricant oil. WD40 is mostly used for getting out the water from rusted bolts. You have to apply the lubricant to both the drill bit end and the working piece for a smooth cut. Apart from these, spraying lubricant periodically on the hardened steel effectively reduces friction.

Make a pilot hole

Wear your safety glasses before starting drilling into metal for eye protection. Wearing closed-toe shoes and a long-sleeved shirt is also a vital safety measure. After that, find the divot in the hardened steel and set the bit in it. Hold the power drill straight to prevent making a crooked hole. Set the drill’s speed setting at a lower RPM and apply steady downward pressure through the steel. Don’t drills into the steel consistently and frequently stop drilling so the drill bit can cool down.

Apply some lubricant between the drilling intervals. Remember, drilling into the steel at a faster speed can damage both the drill and the work piece. Being consistent with light and steady pressure is vital, especially for creating smaller holes to prevent breaking the drill bit.

Pulse drilling before getting through completely

When you are about to break through the other end of the steel, pulse the drilling process. Still maintain a strong grip, but reduce the pressure slightly until the drill bit goes completely through the other side of the steel. After finishing the drilling task, pull out the bit from the hole, keeping it spinning. Be careful, as the power drill may catch on the hardened steel and tend to spin in your hand.

Enlarge the hole

After creating a smaller hole, it’s time to enlarge it using the larger size bit. If you need to create a fairly large hole, gradually increase the diameter of the bit. Try to use three or four different sizes of bits to get the final size. Simply repeat the method using a larger size bit to make the final size hole. Start by placing the bit into the center of the existing hole and gradually drilling it again.

Apply lubricant in the steel and pulse the bit if you reach the end. If you notice smoke while drilling, apply more lubricant or reduce the drilling speed. Apart from these, keep the hole straight by using a manual level or If your drill has a level built-in, use it.

Don’t remove the hot drill bit

Because of drilling into hardened steel, the surface and the drill will be very hot to the touch. It’s better to let the bit cool down before pulling it out. So give the drill bit a minimum of five minutes to cool.

Remove the excess lubricant

Wipe away the remaining lubricant with a brush or a shop cloth from the hole. Carefully hold the shrapnel and throw it in the trash. But don’t hold it with your bare hands as the sharp point can injure you. Dry the hardened steel surface completely and make it free of debris.

Smooth out the edge of the hole

Drilling through hardened steel will leave a sharp edge, which can cause injury while used for further purposes. So smooth the edge of the hole using a medium or heavy metal rasp on the surface of the hardened steel. Make sure you aren’t damaging the steel while filing and execute lightly. It’s also better to use a rasp that fits inside the hole so you can smooth the hole completely.

FAQs on How to Drill through Hardened Steel

Which is the best type of drill bit for hardened steel?

Drilling through hardened steel is quite difficult, and it requires a tougher bit. A cobalt drill bit would be the right kind of bit to handle such a challenging task. It’s a type of HSS drill bit that has 5%–8% cobalt and is sturdy enough to drill into hardened steel.

How to soften the hardened steel for drilling?

Firstly, place the hardened steel in a heated oven and gradually increase the temperature to heat the certain austenite area. Hold the hardened steel in this position for a minimum of 30 minutes. Then slowly lower the temperature. Finally, cool the metal to prepare it for further purposes.

Can tungsten carbide cut through hardened steel?

Carbide burrs with a single flute come with a right-handed twist flute. Therefore, tungsten carbide is great for cutting through hardened steel as well as stainless steel, copper, cast iron, and other hard metals.

Final words

Drilling into metal is always a challenging task, and the toughness of hardened steel makes it extremely difficult. Hopefully, now you can conquer the task since you already know how to drill through hardened steel effectively.

While dealing with hardened steel, make sure you are following every step, including the dent, pilot hole, smaller hole, and the required diameter hole. Above all, use the proper drill bit and follow all safety precautions, especially wearing eye protection goggles, to complete the task safely.

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Sam Morgan is a professional interior designer and part time content writer of Machine Handyman. He is a lifelong tools enthusiast and loves accessories of all shapes and sizes! He always research on different types of improvement tools like drill, air compressor, saw, nail gun, screw gun, grinder, cutting tools etc. Sam works hard on his project and try to find out which machine or tool will get him perfect results.

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