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Stainless steel is a popular material with many applications. It is valued for its resistance to rust, corrosion, and staining. Many DIYers assume you need special tools or training to drill through stainless steel, but it’s actually quite easy with the right tools and good instructions.
In fact, the average handheld drill is perfectly capable of boring through stainless steel. Whether you’re performing maintenance on your boat or installing a soap dispenser in your kitchen sink, follow these steps to safely and easily drill stainless steel.
How to Drill Through Stainless Steel
Stainless steel is a thin metal. With the right steps and process, it isn’t very difficult to drill into.
- Clamp the stainless steel to your work surface. Never trust your hand to stabilize steel while drilling. If the drill catches, you won’t be able to control the metal. Serious injury could occur as the metal whirls around the drill bit like a propeller blade.
- Open the chuck of your drill and insert an appropriate drill bit. You need a twist drill bit made of HSS (high-speed steel) or cobalt. Bits with titanium nitride tips may reduce friction, helping you achieve a better result. Tighten the jaws of the chuck using the drill key. If you have a keyless chuck, the collar on the tip of the drill barrel is used to open or close the jaws.
- Pre-drilling helps prevent the drill from being thrown off course. Drilling a pilot hole is strongly recommended for holes larger than 3 millimeters. Choose a bit that is 3-4x smaller than the intended final result. After the pilot hole has been drilled, follow up with a large bit to get the hole to the right size.
- Stainless steel can be damaged or discolored by the heat of the debris coming out of the hole. If you’re concerned about this, place a strip of duct tape where you will be drilling. The duct tape protects and reinforces the material.
- Use a permanent marker on top of the duct tape to mark the exact center of the intended hole. This is where you will place your drill bit. Some people find it helpful to punch a guide hole or dent to mark the spot.
- Choose appropriate eye protection. If you are wearing safety glasses, make sure they have side shields. Wearing a full-face shield is recommended to protect your entire face from shards of hot metal that may fly through the air. The entrance of the hole and any debris that emerges from it will be hot enough to burn, so you may choose to wear gloves.
- Double check that the stainless steel is securely attached to your work surface before you start drilling. If you have an adjustable-speed drill, set it to half speed.
- Grasp the drill like a handgun in your dominant hand. Place the other hand on the back of the drill. Plant your feet firmly on the floor and extend the drill in front of you. Position the drill at a 90 degree angle to the material. Squeeze the trigger and run the drill for a few seconds before introducing it to the surface of the material and apply firm, steady pressure.
- You should see a continuous metal spiral emerging from the hole as you drill. This confirms that you’re applying enough pressure to the drill. The spiral should be the same color as the metal you’re cutting, or it could look yellowish. If it is darker than the source metal or doesn’t come out in a spiral, this is a sign that the steel has become too hot.
- Take a break at least once every 30 seconds, to allow heat to dissipate. When stainless steel gets hot it becomes harder and more difficult to drill through. Common causes of overheating are; dull bits, drilling too slowly, and drilling too quickly. Larger bits will heat up faster than smaller bits, because of the increased surface area rubbing against the steel.
- Aim for a medium-low speed to ensure the steel stays relatively soft and easy to work with. Apply cutting oil frequently to the drill bit and the hole. If you’re using a battery operated drill, you can dip the bit in a cup of water periodically.
- When the hole is the right size, remove the bit from the hole and release the trigger. Disconnect power from the drill and allow the metal to cool down. Remove the duct tape. Use sandpaper or a file to remove any burrs or rough edges.
Do I Need an Expensive Bit to Drill Stainless Steel?
Boring through stainless steel requires the operator to add pressure while drilling. This enables a good handheld drill to navigate through steel, but increases the chance of bit failure. Choosing the right bit saves time and money.
Opinions are divided on which bit is best for drilling stainless steel. How can you move forward?
First, check the material of the bits you already own. Most standard bits are made from carbon steel or high-speed steel (HSS). While carbon steel bits work on wood, plastic, and even some metals, they are not hard enough to drill through stainless steel.
- High-speed steel (HSS) bits are slightly pricier, but should make it through stainless steel, especially if they are tipped with friction-reducing titanium nitride. You might want to have a few extras on hand if you’re drilling a lot of holes, as they will wear down with repeated use.
- Bits made of cobalt are more expensive than stainless steel. Cobalt is also a harder metal, so it can cut through stainless steel without wearing down or breaking.
- The most expensive bits are made from carbide. Carbide stands up well to nonferrous metals such as cast iron, but is not effective for drilling stainless steel.
For the greatest longevity and best results, get a drill bit made of cobalt.
You can also try sharpening the drill bit that you have on hand. This might make it easier to puncture through the stainless steel.
Stainless steel can be penetrated by a handheld drill with a cobalt or high-speed steel bit. Care must be taken to avoid overheating. Accidental overheating can cause damage and discoloration of the metal.
It increases the risk that the steel will ‘work harden’, becoming more difficult to drill through. Use lubrication or water to avoid this. Proper protection includes goggles and gloves, with a full-face shield recommended but not required.