I Learned the Hard Way: How to Open a Padlock (and When Not To, for Safety)

You can open a padlock with a shim or a bypass tool in under 30 seconds. That's not the skill you actually need.

I've been handling safety equipment orders for Master products since 2017. In my first year, I made a classic mistake: I ordered 200 lockout hasps—the Master Lock 420 models—without checking if the crew actually needed bypass features. The result? $1,200 worth of gear that sat in a crate for six months while we rushed expedited replacements. That's when I learned that knowing how to open a padlock is easy. Knowing which lock to use—and when not to open it—is the real job.

So here's the direct answer: If you need to open a padlock because you lost the key, use a shim (for basic laminated locks), a tension wrench + rake pick (for pin-tumbler locks), or call a locksmith for high-security models. But if you're in a lockout/tagout (LOTO) situation, you must not bypass the lock. This isn't about being clever with tools; it's about workplace safety.

Why you can trust this guide (and my mistakes)

I'm not a locksmith. I'm not a security researcher. I'm a procurement specialist who's ordered and seen the performance of more than 3,000 padlocks over eight years. I've documented 17 significant ordering errors, totaling roughly $15,000 in wasted budget. My team now uses a pre-check checklist I built after those mistakes.

One of the worst was in September 2022. I approved an order for a "master lock electrical lockout tagout kit" without checking if the included hasps (the 420 series) were compatible with the company's existing circuit breaker panel. They weren't. The kit had the right padlocks but the wrong hasp size. $890 in redo costs, a 1-week production delay, and a lot of uncomfortable meetings.

Since then, I've made it my mission to understand the range of Master's products—not just the locks, but the safety glasses, work gloves, and hard hats we buy alongside them. Here's what I wish someone had told me about choosing the right padlock and when to open it.

The "how to open a padlock" question is a trap

It's tempting to think that knowing a few quick tricks makes you a security expert. YouTube is full of videos showing people opening a Master Lock combo lock with a paperclip or a shim in seconds. It's impressive. It's also a deeply misleading skill if you work in industrial safety.

Here's the breakdown of the main methods for opening a padlock:

• Shimming: Works on many laminated locks (including older Master Loto padlocks). You slide a thin metal shim between the shackle and the locking mechanism. It's fast, but it doesn't work on shrouded shackle locks or disk locks.
• Bypass tools: Tools like the "universal bypass" are designed for specific lock weaknesses. They can open some Master padlocks quickly, but they're often specific to certain models.
• Picking (rake/scrub): This works on padlocks with pin-tumbler cylinders. With a tension wrench and a rake pick, a beginner can open a standard 4-pin padlock in under a minute. A more experienced person can do it in 10 seconds.
• Brute force: Bolt cutters, angle grinders, or hammers. This destroys the lock. It's a last resort.

But here's the thing: the ability to bypass a padlock doesn't mean you're in a secure system. In a workplace, a bypassed padlock can mean a bypassed safety procedure. That's why I focus on the Master Lock 420 Lockout Hasp and Master Lock Electrical Lockout Tagout Kit as my go-to solutions—not because they're the hardest to open, but because they make it difficult to bypass the safety protocol by mistake.

The real lesson: Know your application, not your tricks

My second big mistake came from overconfidence. I saw a colleague open our facility's storage shed padlock with a shim in 20 seconds. I thought, "Great, this lock is useless." So I ordered high-security padlocks with disk cylinders for everything. Turns out, the shed padlock didn't need high security. Our workers needed to access it quickly every day. The high-security lock was slow and annoying. They ended up leaving it unlocked, defeating the entire purpose.

I wasted about $600 on locks we didn't need and created a worse security situation because I didn't understand the practical boundary of my own expertise. I'm not a security risk assessor, so I can't tell you exactly what threat model you face. What I can tell you from a procurement perspective is this: match the lock to the risk, not to your curiosity about lock-breaking techniques.

For example:

• If you're securing a personal toolbox in a low-risk area, a standard Master Lock combo lock is fine. If someone wants to open it, they can, but the chance of an actual threat is low.
• If you're implementing a lockout/tagout (LOTO) program for industrial machinery, the best option is a Master Lock 420 Lockout Hasp with a dedicated LOTO padlock. These are designed to be opened only by the person who locked them out, using a unique key. There's no bypass tool that should work. You're buying a policy as much as a lock.
• If you're securing a perimeter fence, like a Buckley fence (which is a type of security fence often made of galvanized steel), the padlock needs to withstand weather and potential tampering. A shrouded shackle lock or a weather-resistant padlock is better than a basic laminated lock.
• If you're in a workplace that requires personal protective equipment (PPE), don't forget that the right work boots and safety glasses are just as important as the lock. You don't want to have a padlock that's easy to open but have someone slip on a wet floor because they're wearing the wrong boots.

The boundary: When to call a professional

The "open a padlock" question gets tricky when you're dealing with high-security or specialty locks. For example, a high-security padlock with a restricted keyway (only the manufacturer can duplicate keys) is designed to resist picking and shimming for a long time. But if you lose the key, you can't just improvise a solution. You need the manufacturer or a certified locksmith.

This was accurate as of Q1 2025. The lock industry changes—new bypass tools emerge, new standards are adopted—so verify the current state of the locks you're buying. I learned this in 2020 when I assumed a lock was pick-resistant. It wasn't. The lesson: don't assume your knowledge is current.

I'd also recommend consulting an actual safety professional (like a Certified Safety Professional or a site safety manager) before finalizing a LOTO system. This gets into compliance territory, which isn't my expertise. Your legal team and safety officer should review the procedures.

Final thought: The skill isn't in opening the lock

Knowing how to open a padlock is a party trick. Knowing which padlock to buy for which purpose is a professional skill. And knowing when not to open a lock at all—because it's part of a LOTO program—could save a life.

I've made enough mistakes with Master's product line to know that the right tool for one job is the wrong tool for another. A Master Lock 420 Lockout Hasp is a fantastic tool for industrial safety. A Master Lock combination lock is great for a locker. A Bluetooth padlock is brilliant for shared access. But none of them are universal. The vendor who tells you what they don't do is the one you can trust.

My advice? Buy the right lock for the risk, lock it properly, and leave the bypass tricks for YouTube. Your workplace safety program—and your budget—will thank you.