Drilling out a lock is a last resort — it permanently destroys the lock cylinder, so you'll need to replace the entire lock afterwards. Before you reach for the drill, it's worth exploring alternatives like calling a locksmith, checking for a spare key, or contacting your landlord or property manager. If you've exhausted every option, here's what you need to know.
Try These Alternatives First
Drilling is irreversible, so consider these options before you start:
- Call a locksmith — A qualified locksmith can often pick or bump a lock without destroying it, saving you the cost of a full replacement. You can find local locksmiths on tradedirectory.co.nz.
- Check for a spare key — With a neighbour, family member, or property manager.
- Contact your landlord or property manager — If you're a tenant, your landlord has obligations under the Residential Tenancies Act and may have a master key.
- Check other entry points — A window latch or back door you may have left unlocked.
If none of those work and you own the property, drilling may be your only option.
What You'll Need
Understanding How a Pin Tumbler Lock Works
Most residential door locks in New Zealand use a pin tumbler cylinder. Inside the cylinder are several spring-loaded pin stacks. When the correct key is inserted, it lifts each pin stack to the exact height needed to align a gap (called the shear line) between the driver pins and key pins, allowing the cylinder to rotate. Drilling destroys these pins so the cylinder can turn freely — or be removed entirely.
Step-by-Step: How to Drill Out a Lock
1. Put on Your Safety Glasses
Metal fragments and spring components can eject at speed. Eye protection is non-negotiable.
2. Apply Penetrating Oil
Spray a small amount of penetrating oil into the keyhole. This reduces heat and friction during drilling.
3. Start With a Small Pilot Hole
Using your 3 mm drill bit, position the tip at the top of the keyhole, right at the shear line — this is typically about halfway up the face of the cylinder. Drill slowly and steadily into the lock at a slight upward angle, following the line of the pins. Keep the drill level and centred. Drill to a depth of roughly 20–25 mm (most pin tumbler cylinders have 5–6 pin stacks spaced a few millimetres apart).
4. Step Up to a Larger Bit
Switch to your 5 mm or 6 mm bit and drill along the same path. This widens the channel and destroys the remaining pin stacks. You may feel or hear the pins breaking as you go — this is normal.
5. Test the Cylinder
Insert a flathead screwdriver into the keyhole and try to turn the cylinder. If the pins are fully destroyed, it should rotate. If it doesn't, continue drilling in short bursts.
6. Remove the Lock
Once the cylinder turns, you can retract the latch and open the door. Remove the lock cylinder from the door by unscrewing the retaining screw on the edge of the door (the set screw) and pulling the cylinder out from the front.
7. Replace the Lock
You must fit a new lock — the drilled cylinder is destroyed and cannot be re-used. Take the old cylinder to your hardware store to match the size. Standard NZ residential locks are commonly 60 mm or 70 mm backset — measure yours before buying.
Choosing a Replacement Lock
When selecting a new lock, look for products that meet an applicable New Zealand or Australian/New Zealand standard for locks and latches, or carry an equivalent recognised security rating. Deadbolts are generally more secure than knob or lever latches alone. PlaceMakers, Bunnings, and Mitre 10 all stock a range of residential locksets. Check the manufacturer's installation instructions carefully.
Important Safety and Legal Notes
- Only drill a lock on property you own or have explicit written permission to access. Drilling a lock on a property you don't own or have no right to enter could constitute an offence under the Crimes Act 1961.
- If you are a tenant, do not drill or replace locks without your landlord's written consent — this is a condition of most tenancy agreements and is covered under the Residential Tenancies Act.
- Keep children away from the work area — drill bits, springs, and metal shards are hazardous.
- Consult WorkSafe NZ guidelines if you're unsure about safe tool use.
When to Call a Professional
Call a qualified locksmith if:
- You're not confident using power tools safely.
- The lock is a high-security, smart, or multi-point locking system — these are significantly more complex to drill and replace.
- You're a tenant — your landlord should arrange access.
- The door is a fire door — replacement locks on fire doors must comply with the NZ Building Code and may require specific hardware. Check with MBIE Building Performance or your local council.
- You want to avoid damaging the door itself.
A professional locksmith will often get you back inside faster, with less damage, and at a comparable or lower total cost once you factor in replacement hardware. Find a trusted local locksmith on tradedirectory.co.nz.
