A Step-by-Step Guide to Drilling Holes in Metal

Metal is a key component in countless construction projects. Aluminium and steel are the most prevalent, but copper, brass, and bronze are also commonly used.

When using a metal piece in your project, you may need to drill into it at some point. Metal’s harder composition makes getting a clean, precise hole more difficult than drilling through wood or masonry, so there are a few things you need to consider before you get started.

Clickmetal are the UK's premier suppliers of aluminium, brass and stainless steel pieces. Read on for our step-by-step guide to drilling through metal precisely, from choosing the right drill bit to deburring the hole.

1. Protect Yourself

Safety always comes first. As with any construction project, it’s important to take steps to protect yourself from injury.

Drilling into metal can cause tiny shards to fly off at high speeds. If one lodges itself in your eye, you’ll soon find yourself on an unpleasant trip to A&E. Make sure you’re wearing appropriate eye protection before you start drilling; safety glasses that wrap around the sides of your face are the best option.

Gloves, loose clothing, and long hair can get wrapped up in the drill bit as it spins, risking serious injury. Avoid wearing anything with hanging parts and keep long hair securely tied back.

If you’re using a drill press, never try to adjust it while it’s running.

2. Clamp Your Metal in Place

Trying to drill into a piece of metal without securing it is a recipe for disaster. If the drill bit catches, it could cause the metal to spin around violently, slashing at anything and anyone in the vicinity.

Place your metal on a sturdy surface and use at least two clamps to hold it in place.

3. Make a Dimple

It’s not unusual for your drill bit to shift when you first start drilling. This could cause the hole to be strangely angled or in the wrong place, so it’s a good idea to create a ‘dimple’ in the metal first.

Mark the intended hole location with a pen, then use a centre punch and hammer to create a small dip in the metal. This will help keep the tip of your drill bit in place as you start to drill.

4. Start Drilling!

Now that you’ve donned the appropriate equipment and prepared the metal, it’s time to start drilling!

Here are a few tips for drilling neat and precise holes in metal.

• Choose the right bit for your metal. High-speed steel bits, commonly used for wood, are suitable for softer metals like aluminium. For drilling steel or other hard metals, use a stronger cobalt, titanium, or carbide bit.
  
  
• Start off at a slow rotation speed and only go faster if necessary - not only is a slow speed necessary for drilling hard metals like steel, but it will prevent excessive heat from dulling your drill bit. With a small twist bit (up to 13mm), you can drill through most metals at 3,000 rpm. For larger twist bits (up to 26mm), 350 to 1,000 rpm is recommended.
  
  
• If you’re trying to drill a large hole, you’ll likely find it easier to start with a small hole (around 6mm) and drill successively larger holes until you reach the intended size. You could also try using a hole saw.
  
  
• Thin sheet metals can be tricky to work with, as they slide around easily. Clamping your metal sheet between two planks of wood will keep it flat and in place while you’re drilling through it.
  
  
• Struggling with a standard drill bit? Consider swapping to a step drill bit. These cone-shaped bits are great at creating clean, accurate holes in sheet metal and plastic, although they tend to be more expensive than regular bits.
  
  
• Use cutting fluid or multipurpose oil when drilling holes in steel that’s 3mm or thicker. This will help reduce friction and heat buildup, making drilling easier and prolonging the life of your bit. You don’t normally need to lubricate softer metals like aluminium, brass, or cast iron.
  
  
• If you need to drill a lot of holes, it may be worth upgrading to a drill press. They’re designed specifically for metalworking and will create clean, accurate holes virtually every time.

4. Deburr the Hole

The final step is to neaten and smooth any rough edges within the hole. You can use a specialist deburring tool for this, or you can use a drill bit that is slightly larger in diameter than the hole you just drilled. Twist it by hand over the top of the hole to grind away any burrs left over.

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