Introduction: Find the Combination to Your Master Lock!

Picture of Find the Combination to Your Master Lock!

Here's an experience I, and most high school students go through at some point in their life.  You wake up in the middle of the night, and remember that you need a padlock for P.E. the next day.  You quickly rummage through all the junk in your room, and find about five of them, but you have no clue what the combination is for any of them.  You look on the Master Lock website, and there's a two-month process you can go through to get the combination.  You look on youtube and all you can find is a guy with a weird equation that only narrows it down to 100 combinations, which could still take up hours of your time.  This instructable will show you how to find the combination to a master lock.  **Notice!  This is only to be used in an emergency where you need to open the lock.  You should never use it to break into someone else's gym locker.  Besides, there's nothing in there but smelly, sweaty gym clothes, and maybe a stick of deodorant.

Step 1:

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Find the newest looking padlock you have.  This will work with most master locks, but probably not the really old ones.  You will need a padlock and a FLATHEAD screwdriver.

Turn the lock so the back side is facing up.  Pry up the edges around the back using the screwdriver.  It is only important for you to pry up the bottom half of the circle of edges.

Step 2:

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Once you have at least the bottom half of the edge circle pried up, you should be able to slide the back panel off, so it looks like it does in the picture.

Step 3:

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There should be a circular hole like in the middle of the picture where you can see the edge of a circular metal disk.  If your lock by chance does not have one, you can try another lock that might, or attempt to drill a hole.

Step 4:

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Clear the lock by spinning the dial clockwise a few times.  Once it is cleared, look through the hole in the back.  Rotate the dial clockwise until you see a notch in the metal disk inside the hole, like in the picture.  Then, look at what number the arrow on the front of the lock is pointing to.  That is the first number in your combination.  Write it down.

Step 5:

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Now look through the hole in the back again.  Through the notch in the metal disk, you should be able to see another metal disk.  Turn the dial counter-clockwise until you see a notch in that disk as well, that lines up with the first one you found.  Record the number on the front as your second number.

Step 6:

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Again, through the two notches you lined up, you should see a third metal disk.  Turn the dial clockwise again until a notch in the third disk lines up with the other two.  Record the number on the front as the final number in the combo.  Pull on the shackle, and the lock should open right up.

Step 7:

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There you have it.  Slip the back back on, pry the edges back to where they were with the screwdriver or by pushing it on a hard surface.  It may turn out a bit bumpy in the back, but it is a small price to pay to pass gym.  I have used this multiple times and it works.  DO NOT MISUSE THIS INFORMATION.  I WILL NOT ASSUME ANY RESPONSIBILITY FOR ANY STUPID WAY YOU ABUSE THIS METHOD.  If you have any questions, comments, or emotional outbursts, feel free to leave a comment, and I'll try to get back to you.


GregF8 (author)2015-07-12

GregF8 (author)GregF82015-07-12

Remember to mark where the back and case align before taking it apart. Needed to drill the hole in my model. Used a 5/16 drill bit. Took about a minute and a half. After that, it all worked perfectly. Helped that I remembered pat of the combination, once the numbers started lining up. Sure easier than the mathematical solution.

muna.rana07 (author)2015-03-03

I have failed at step 1.

Fission Chips (author)2014-10-25

Really handy! Thanks for sharing this.

kutz (author)2013-05-07

I remember helping my friend get his locker open with this technique, The only problem i found on the lock he had was that it had to line up with a notched lever. The holes may line up properly, but unless you line them up to allow the lever to extend further there's no way it'll budge!

ElizabethGreene (author)2012-09-13

Option B. Drill a very small hole on the back at the 10:30 position 3/4 inches from the center. Then use a paperclip to decode the combination.

throbscottle (author)2012-09-11

Excellent instructable - I love that something quite complex can be solved so simply!

Re The Great Screwdriver Debate - I think I just call it a screwdriver, or a normal screwdriver, or a flat screwdriver, or a plain screwdriver, or an "ouch you B*****d!" when I've stabbed my hand with it trying to use it as a pry-bar :(. I may have used the terms flat-head, flat-blade, flat ended, or whatever, but I don't remember and I don't really care. Anything else I call it pozidriv, philips, torx allen, a nut-spinner, ... whatever it happens to be. Most of the time I don't call any of them anything because I'm using it not talking about it. You use language appropriate to the situation - if it's design engineering you speak that language, if it's Instructables or similar, you speak to the masses.
Just my 2p's worth.

omalachowski (author)2012-09-02

Guys, can't you just do these the old way? You just keep tugging lightly on the lock as you rotate the dial CCW, then when it pulls a bit, you reverse directions, and a third time and that's your combo.

Perhaps they've safeguarded them on more modern locks, but I've done this on dozens of locks and it really works. No drilling no muss. It's also possible to undo a lot of these with a shim.
Or you could just...y'know...remember your combo.

darman12 (author)omalachowski2012-09-03

Huh, interesting...thanks for the idea :)

omalachowski (author)darman122012-09-03

Yeah, I've done a bit of reading up on this. There's a lot of methods on youtube, including ones using a pop can to make a shim, a bobby pin, and math to suss out the code. I don't have a Master Lock, but on the cheap combo lock I could find, it's very easy to feel the discs turning and locking into place. I assume it must be harder on a MasterLock, but I'm going to have to wait until I have one to try.

Point of all this should really be that a MasterLock, or any combo lock, is not a secure way to lock anything. Use a serious key lock, or just use a twist tie.

darman12 (author)omalachowski2012-09-03

I've done the math one, it worked pretty well. I only had to go though about 20 combinations out of 100 to get it. Haha, twist tie.

DIY-Guy (author)darman122012-09-05

I tried the twist-tie security method to keep honest people honest. But it was too tempting to the dishonest people who were not smart enough to figure out how to crack a combination lock. 99 out of 100 people who want to mess with you will do it if you don't use a real lock. Only 1 out of 100 of these jerks is smart enough to learn the skills to pick a lock. Twist-ties failed me 99% of the time, a lock only failed to protect me 1% of the time.

omalachowski (author)DIY-Guy2012-09-05

I'm not sure how to reply to that. I guess I've never had either method fail that I remember...? So I agree with you, I think, inasmuch as: A deterrent is only as strong as the person facing it thinks it is. A master lock is much more serious-looking than a twist-tie, but it's still easy foiled. There's better locks in the world.

darman12 (author)DIY-Guy2012-09-05

Haha, doesn't seem like the best would be a little better :P

Thanks. I saw that online but it didn't seem to work for me. Great idea though.

woooshhhhh (author)2012-09-04

Nice instructable

Thank goodness they don't spot weld those lock backs.

I hear that!

snatr (author)2012-09-02

You can save yourself a lot of time with a shim :)

epicleprechaun (author)snatr2012-09-02

Yes, you probably can, but I don't believe you can get the combinations from it. :)

snatr (author)epicleprechaun2012-09-04

Depending on the lock, once you have it open you may be able to see the tumblers.

EconoProbe (author)2012-09-02

Just to muddy to water a bit, I always refer to a "flathead" screwdriver as a "common" screwdriver; This has been my habit for 50+ years and nobody has ever questioned what I mean.

I reserve to term flathead for screws. A flathead screw can have many forms of drive, common (slotted), phillips, Torx, square, etc.

Not saying any of the rest of you are wrong, just throwing another term into the mix.

Golden Rocket (author)EconoProbe2012-09-03

Flathead is two things for me - first and foremost it is an old engine design most famous were those in the old fords - secondly, it is a type of screww exactly as econoprobe describes.

What you call "common" screwdriver, I labelled is as the flat tip, flat bit or slotted bit screwdriver

EconoProbe (author)Golden Rocket2012-09-03

If only the slotted screw were as tough and dependable as the flathead Ford V8. I actually tried to lunch one on a down grade in AZ. About 7 miles with it floored doing about 80MPH (normal top speed was about 60 on a good day). I was through with the truck and was a stupid teenager. Two years later the old beast was still chugging along when it was sold.

BTW, got so caught up in the "flathead" controversy that I forgot to congratulate epicleprechaun on a fine Instructable.

Now, does anybody have a secret for finding the combination of a padlock with 4 rotating dials in the bottom? I've had one lying around for over 20 years and I just hate to throw anything away. :-)

WiringHarness (author)EconoProbe2012-09-04

@Econo, If your 4 dials are digits, that's only 10,000 combinations. It should only take 1-2 seconds to try each one, so you should be able to find your combo in a few hours of TV viewing (or whatever else you do while relaxing).

darman12 (author)EconoProbe2012-09-03

Is a slotted screw like Phillips? The one that has an X looking hole?

EconoProbe (author)darman122012-09-03

No, it's a screw with a single, straight, slot.

darman12 (author)EconoProbe2012-09-03

Oh, I know what you're talking about, thanks :)

engineeron (author)EconoProbe2012-09-03

"I reserve [the] term flathead for screws. A flathead screw can have many forms of drive, common (slotted), Phillips, Torx, square, etc."
Exactly the point I was trying to make in the first place . . . and doing so for the purpose of improving clarity (just as I specifically said in the very first sentence, which also observed that IMO this was a minor point), rather than to criticize the grammar.  I have no wish to be seen as a Grammar Nazi - but I do believe that being lazy or sloppy with terminology and grammar makes communication more difficult in the long run.  If I order flathead screws, and learn later that the vendor has sent slotted panheads because he believes that "flat" only has to do with the drive slot, they're going back, and that vendor will not see another order from me. 
"Common" screwdriver makes sense - but today, it seems like there are more Phillips drive screws than slotted ones.  That sure wasn't the case 50 years ago!  Back then, you would have "typed" something, rather than keying it in or keyboarding, and dialed a phone, rather than punching the number.  Terms tend to lag behind the technology changes.

Lost, either in editing, or removed after posting(?) was a statement I made pointing out that I was NOT criticizing the Instructable itself, which appears to be straightforward and useful, though I have not actually tried it.  (Thank you, epicleprechaun)
And the "preview" button still doesn't do anything . . .

Bugsley (author)2012-09-04

Great Instructables!

If you have more of these lock without combos,
use the first lock back as a template.
locate the hole where the 'disks' line up.
drill a small hole in this location on your next one.
get the combo, and then refill yhe hole with epoxy.
ps. you can also get the reverse left, right, left, combo using your technique.

LesB (author)2012-09-03

I've never heard of a flathead screwdriver, maybe it's a regional thing. But I have absolutely no problem with the terminology. Farz I'm concerned, people can call it an iridmiccible dokkelfier if they so please.

But in calling it flathead, that could be confusing because there is such a thing as a flathead screw and one might think that a flathead screwdriver is meant for driving flathead screws. Flathead screws can be made to accomodate any number of drives: phillips, square, hex, and whatever.

Actually, in the podunk town I originally came from we just pointed to the tool and said "that thing". Keeps it simple.

darman12 (author)2012-09-03

Heeeey, I might suggest the flat-head/flat-bladed screwdriver discussion for a debate in my speech class this year, seeing as it causes so much discussion. Muhahaha. Though, everybody probably calls it flat-head and will say "What? Flat-bladed??"

darman12 (author)2012-09-03

Shows as flathead as a correct term although all the others are correct as well.
flat blade, slotted, flathead......" - tmgcough

Ok, tmgcough is the only one that has provided any citation for the actual term...this helps alot...thank you very much for giving an actual conclusion (with proof) to this debate, haha! XD

darman12 (author)darman122012-09-03

Wikipedia also give credibility to all of our terms:
"The tool used to drive a slotted screw head is called a "flat-blade", "slot-head", "straight", "flat", "flat-tip",[3] or "flat-head"[4] screwdriver." This also give insight into the slotted screw. The 4 next to flat-head (which denotes a foot note (haha...dispute foot-note)) refers back to the e-book which tmgcough shared with us, I also posted it above.

Wikipedia link:

Here is an excerpt from another article on screwdrivers ( the article is on the homepage) :

"[A screwdriver] It is made up of a head or a tip" This explains the origin of "flat-head" or "flat-tip".

tmcgough (author)2012-09-02
Shows as flathead as a correct term although all the others are correct as well.
flat blade, slotted, flathead......

darman12 (author)tmcgough2012-09-03

Haha, you are the only one that actually has citation for the correct term...thank you XD

Doc_Cottom (author)tmcgough2012-09-02

I have a Mac Tools flatblade screwdriver that is 36 inchs long with a heavy duty wooden handle. The tip is around 3/4 inch wide. It has never found a screw that would fit it, but it's a great pry-bar, belt tightner, flywheel turner, and pinion nut lock. That tool is termed "papaw's BIG screwdriver!

ac-dc (author)2012-09-02

So instead of carrying around the combination written down, you expect to have a flat bladed screwdriver handy? Consider stenciling the combination onto the handle of the screwdriver so when you take the screwdriver to the lock you will have two options. :)

IMO, this instructable makes no sense at all. So what if you have the combination since you wo't want to try to reassemble the lock and keep using it? If you lose your combination the thing to do is contact the owner of the lockers who will have a bolt cutter on site that can get the lock off in a few seconds.

Next, buy a new lock like you'd end up doing anyway.

darman12 (author)ac-dc2012-09-03 obviously didn't read the first step (the very first page). He explained that when you need a lock for school, you search in your house and find one, but you have forgotten the password. That is why you would have a flat bladed (or flat head) screwdriver "handy"; because, it is a common house hold item.

This instructable is not aimed to getting into a locked locker with which you forgot the combination. I hope this makes more sense to you. :)

epicleprechaun (author)ac-dc2012-09-02

I do not expect everyone to carry a screwdriver around when they want to open their lock. This was made with the impression people would use it to find the combination and write it down for future reference. Also, it is perfectly easy to reassemble, and you can continue using it just fine.

Sorry for any miscommunication.

LesB (author)2012-09-02

I would like to use this method to break into a bank vault. You may have given me the key to an early retirement!

epicleprechaun (author)LesB2012-09-02

Ha Ha. I know you meant this as a joke, but to anyone out there seriously considering it, it is not going to work. The modern bank vault has a state of the art security system-way more complicated than a three number master lock. We are talking twenty character passwords, and voice recognition. Tons of stuff like fingerprint and retina scanners.

and then that is when epic computer hacking and emp bombs come into place, or you could just become the best friend of the banker :)

darman12 (author)techno guy2012-09-03

Why don't you just use C4? haha

ndr1968 (author)2012-09-03

"You say tomatoe I say potatoe..." Flathead schmatheat...etc" However, calling a notch a "whole" did get me confused for a bit there!

JasonTX (author)2012-09-03

How does everyone feel about crosstip screwdrivers?

/ducks and runs away

Davidfromcali (author)2012-09-02

I don't know a single person in the last 59 years that would not know what a 'flat head' screwdriver means.

darman12 (author)2012-09-02

Epicleprechaun...I really enjoy your Instructable! It is a very simple and clear process. I have found myself in this situation, haha. The only thing is that you can tell it was tampered with. But that is does the job :)

I have tried the equation thing, it works but does take a while...but it does provide an alternative to opening the lock. Whatever floats your boat is what I say.

Also, I have been interested in what the inside of a Master Lock looks like, thanks for the insight...maybe post a photo album of it completely disassembled, that would be cool. If you do post that it would be the way, i'm subscribing to you :)

darman12 (author)darman122012-09-02

Oh, i'm also voting :)

jonwells (author)2012-09-02

What would you do with a shim? Does that mean something like a feeler gauge?

dulciquilt (author)2012-09-02

I live in Texas and we have always called them flathead screwdrivers. It may just depend on what country or what part of a country in which you live.

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