How NOT to Drill Open a Mul-T-Lock: Multi-Lock Cylinder Disaster. A Costly Mistake! We examine a multi-lock cylinder that was mishandled by someone unfamiliar with its mechanics. The individual incorrectly drilled the shear line, then attempted to salvage their error using a checkerboard grinder. Unfortunately, their efforts resulted in further damage to both the cylinder and the lockbox, ultimately costing the customer an estimated $300 to $500. Watch to see the full extent of this costly mistake. High-security locks demand high-level knowledge—and when that knowledge is missing, the results can be costly. (Source: Terry Whin-Yates)

Source: Mr. Locksmith Youtube http://www.youtube.com/user/24hrMrLocksmith

How NOT to Drill Open a Mul-T-Lock

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Mr. Locksmith Automotive (604) 259-7617

As a locksmith, you sometimes see jobs that make you shake your head—and this is one of them.

This is a Mul‑T‑Lock cylinder that was drilled by someone who clearly didn’t understand how the lock actually works.

In this post, I’m breaking down a real-world example of how not to drill open a Mul-T-Lock cylinder. What should have been a controlled, professional opening turned into a destructive guessing game that ruined both the cylinder and the lockbox, leaving the customer with an expensive repair bill. This is a perfect lesson in why understanding lock design matters, why drilling is a last resort, and why high-security locks should only be handled by trained locksmiths.

What Went Wrong

Whoever attempted this opening made several critical mistakes:

They drilled the shear line incorrectly – way too deep and in the wrong location.
They tried grinding the face with a checkerboard-style attack, which didn’t accomplish anything useful.
They kept drilling anyway, completely destroying the cylinder and lock box.
In the process, the lockbox itself was also destroyed.

Yes, the lock was eventually opened—but at a huge cost.

The Real Cost of Doing It Wrong

Because of this attempt:

* The Mul-T-Lock cylinder was ruined
The lockbox was destroyed
The customer was likely left with a bill in the $300–$500 range, possibly more once replacement hardware and labor were added

And that doesn’t even account for what the original “driller” may have charged for creating this mess.

* Note: Most High Security Locks are “Pick Resistant” and one bypass method is to drill the lock open. However, do not damage the door or additional hardware

Why Mul-T-Lock Is Different

Mul-T-Lock cylinders are high-security locks. They are not standard pin-tumbler cylinders, and they are absolutely not meant to be attacked like one. Without proper knowledge of:

Internal pin structure
Shear line locations
Drill-resistant components

you’re almost guaranteed to cause unnecessary damage.

The Locksmith Takeaway

This is a perfect example of why:

High-security locks should be handled by trained professionals
Drilling should be a last resort, not a guessing game
Lack of knowledge costs the customer real money

A proper locksmith could have evaluated non-destructive options—or at the very least drilled it correctly with minimal damage.

Final Thoughts

Opening a lock isn’t just about getting it open—it’s about doing it properly, professionally, and with minimal damage. This Mul-T-Lock job shows exactly how not to do it.

If you’re dealing with a high-security lock, make sure the person working on it actually understands what’s inside.

— Terry, Mr. Locksmith 🔐 Source: Terry Whin-Yates Mr. Locksmith Linkedin