How to Drill a Hole in a Deadbolt

How to Drill a Hole in a Deadbolt

Adding an extra hole to your deadbolt can allow you to install an additional lock or security feature like a smart lock or chain guard. While it may seem daunting, drilling a clean hole in a deadbolt is totally doable with the right tools and preparation. This comprehensive guide will walk you through everything you need to know to drill into a deadbolt successfully.

Benefits of Drilling a Deadbolt

Why would you want to drill a hole in your deadbolt in the first place? Here are some of the key benefits:

  • Add an extra lock: Drilling a second hole lets you install an additional lock above or below the deadbolt for added security. This is great for exterior doors.
  • Install a smart lock: Many smart locks require drilling a hole in the deadbolt to mount the lock. This allows you to add keyless entry.
  • Attach a guard: A hole enables installing a protective chain guard outside the door above the deadbolt.
  • Create alignment: An extra hole can help align and stabilize the deadbolt if the original holes are slightly off.

Choose the Right Location

Before you start drilling, determine the optimal location for the new hole. Here are some tips:

  • Measure the existing bolt holes to position the new hole evenly.
  • Allow enough space between holes for the drill bit. At least 1/2 inch is ideal.
  • Keep the hole centered vertically on the bolt.
  • Place the hole above or below the bolt rather than directly beside it for best alignment.
  • Check that the location has enough depth for the screw or attachment.

Pro Tip: Use a template based on your deadbolt measurements to mark the hole placement accurately.

Gather the Right Drilling Tools

Drilling a clean, precise hole requires having the proper drilling tools on hand. Here’s what you’ll need:

Safety Equipment

  • Safety goggles – Protect your eyes from debris.
  • Work gloves – Guard your hands from sharp edges.
  • Dust mask – Avoid inhaling metal shavings.

Drilling Tools

  • Cordless drill – Provides mobility and power for drilling metal.
  • Drill bits:
    • Small pilot bit – Creates a guide hole for the larger bit.
    • Step bit or spade bit – Cuts a wider hole to the desired size. Match to your bolt size.
  • Cutting oil – Lubricates and cools the drill bit during cutting.
  • Rag – Apply oil and wipe away metal shavings.
  • Center punch – Marks where to drill to prevent bit wandering.
  • Hammer – Hammers the center punch to make an indentation.
  • Clamp – Holds the deadbolt securely while drilling.

Drilling Safety Tips

  • Wear safety goggles, gloves, and a dust mask when drilling metal.
  • Clamp the deadbolt firmly to a stable surface before drilling.
  • Go slow and use cutting oil to avoid overheating the drill bit.
  • Apply firm pressure but don’t force the drill during cutting.
  • Retract the bit periodically to clear out metal shavings.

Step-by-Step Instructions

Now let’s walk through the entire process of precisely drilling a hole in a deadbolt:

1. Mark the Hole Placement

Use a template or measurements to determine the hole location. Mark the center point with a light punch or center punch. Hammer it lightly to leave an indentation. This will prevent the drill bit from wandering.

2. Clamp the Deadbolt

Attach the deadbolt securely to a sturdy work surface using a vice or clamp. This keeps it fixed in place for drilling. Insert a scrap block of wood to avoid marring the metal.

3. Drill a Pilot Hole

Fit a small pilot bit in your cordless drill. Drill slowly straight down into the indentation to create a guide hole. A pilot hole helps ensure drill accuracy.

4. Enlarge the Hole

Switch to the step bit or spade bit matched to your desired hole size. Coat the bit in cutting oil. Drill slowly, applying firm pressure. The pilot hole will keep the bit stable.

5. Clear Metal Shavings

Retract the drill bit frequently while cutting to clear out metal shavings. This helps prevent binding. Apply more cutting oil to the bit.

6. Smooth Rough Edges

Examine the hole for any rough edges. Use a round file to gently smooth the opening so attachments sit flush.

And that’s it! Just follow these steps carefully to create a clean opening in your deadbolt for adding an extra lock or fixture.

Helpful Tips for Success

To ensure you safely drill an accurate, properly aligned hole, keep these tips in mind:

  • Use cutting oil. This prevents overheating and makes cutting easier.
  • Let the drill do the work. Don’t force it. Apply steady pressure.
  • Retract to clear shavings. Frequently back the bit out to remove metal debris.
  • Drill straight down. Use a center punch indentation to prevent wandering.
  • Clamp securely. The deadbolt must be completely fixed to avoid vibration.
  • Match bit size. Step bit should equal the bolt diameter for a snug fit.

Troubleshooting Drilling Problems

Issue Solution
Bit slips or wanders – Mark hole with center punch – Apply firm pressure when drilling
Rough, uneven hole – Drill pilot hole first – Keep drill steady
Overheating drill bit – Use cutting oil – Drill slowly – Back bit out to clear shavings
Hole too small or large – Use step bit matched to bolt diameter
Metal shavings stuck in hole – Frequently retract bit while drilling  – Smooth hole edges with round file

Additional Safety Measures

Drilling metal always requires caution. Here are extra precautions when drilling your deadbolt:

  • Protect surfaces. Place tape or a rag around the deadbolt to avoid scratches.
  • Unplug when not drilling. Don’t leave a plugged in drill unattended.
  • Keep drill bit sharp. Dull bits require more force and overheat faster.
  • Avoid drill bit breakage. Don’t wedge the bit or twist it in the hole.
  • Wear eye protection. Metal shavings and debris can damage eyes.

Installing the Extra Lock or Fixture

Once you’ve drilled the hole, it’s time to install the secondary lock or fixture:

  • For a chain guard, use the screws provided with the guard kit.
  • For an additional lock, trace the hole placement from the lock to the deadbolt.
  • For a smart lock, follow the mounting instructions to attach to the deadbolt.
  • Make sure all screws are tight for a secure hold. Don’t overtighten.
  • Test the lock operation before regular use.

And just like that, you’ve enhanced the security and functionality of your door with an additional drilled hole in the deadbolt!

When to Call a Locksmith

While DIY drilling is possible, consider hiring a professional locksmith for:

  • Deadbolts with special coatings – Special finishes can crack when drilled.
  • Awkward, hard-to-access deadbolts – Tricky positioning makes mistakes more likely.
  • Alarmed deadbolts – You’ll need the alarm disabled before drilling.
  • Installing high-security locks – Their intricate installation requires expertise.


Adding a strategically placed hole in your deadbolt can allow installing an extra lock or smart technology. With the right preparation, tools, and technique, drilling a clean opening is totally doable as a DIY project. Just remember to mark the location precisely, use a pilot hole, work slowly, and take the proper safety precautions. Your improved security is worth the effort!