Trick Locks: Padlocks With No Keyhole Worth Using

Quick answer: a trick lock is a padlock built so the obvious method fails. The keyhole may be a decoy, the shackle may need turning or pressing in a particular order, or part of the body may move. Roman puzzle locks survive from the 2nd century BCE, and exposed-keyhole puzzle locks were widespread in ancient China.

Best for: people who like puzzle boxes and want the same sequential thinking in something pocket-sized and heavy.

A lock is a puzzle that normally comes with the answer attached to your keyring. Take the key away, or make the key a lie, and you have one of the oldest puzzle forms there is.

Watch: Opening a 3D-Printed Trick Lock

Six minutes on TrickLock 2017 by Louis Coolen, one of a series of four 3D-printed trick locks. It is a good illustration of the sequence problem: the lock gives almost nothing away until the right thing is tried in the right order.

Coolen's series is also worth knowing about because the locks are 3D printed rather than machined from brass, which is an unusual choice in a category that normally trades on weight. It shows the mechanism matters more than the material.

What Is a Trick Lock?

A lock with unusual or deliberately hidden mechanics, where the point is finding the method rather than possessing a key.

The family covers a wide range. Some have no keyhole at all. Some have a keyhole that does nothing. Some accept a key that must then be used in an unexpected way, turned in the wrong direction, inserted twice, or pushed rather than turned. Others need the shackle itself rotated, lifted or depressed in sequence before anything will move.

What they share with everything else on this site is that the solution is a sequence rather than a force, which is the quality described in puzzle box mechanisms.

How Old Are Puzzle Locks?

Genuinely ancient, and much of what is written about them is not.

The earliest surviving Roman puzzle locks date to the 2nd century BCE. In China, puzzle locks with exposed keyholes were in wide use and are often extremely awkward to open even when you can see the mechanism. Egyptian lock-and-key systems, using wooden pins and bolts, predate both.

The padlock itself, in its warded form, is traditionally credited to Theodorus of Samos, the Greek sculptor and inventor also associated with the lathe and the level.

Was the Padlock Really Invented 6,000 Years Ago?

No, and this claim is worth correcting because it appears on product pages for trick locks sold today.

Several retailers state that Theodorus designed the warded padlock over 6,000 years ago. Theodorus of Samos lived in the 6th century BCE, which is roughly 2,600 years ago. The figure is out by a factor of more than two, and it is repeated uncritically across listings for the same product.

The real history does not need the inflation. A puzzle mechanism that has survived in recognisable form since the Roman republic is remarkable on its own terms.

How Do Trick Locks Actually Work?

Four mechanisms account for most of them.

The decoy keyhole. A visible keyhole that connects to nothing, or connects to a mechanism that must be released before the keyhole matters. It exists to absorb your first twenty minutes.

The hidden release. A pin, stud or panel somewhere on the body that must be pressed, slid or rotated. Often disguised as a rivet, a decorative feature or a casting mark.

The sequence. The key, the shackle and the body each do something, and they must be done in one order. Doing them in a different order resets the lock silently, which is what makes these frustrating.

The unexpected key motion. The key fits and turns and nothing happens, because it needs pushing, pulling, half-turning or turning the other way. The lock is not broken; your assumption is.

How Do You Open One?

Map the lock before you touch the key. Look at every face. Find every seam, rivet, stud and casting line, and test each one for movement. Most trick locks give themselves away to a careful inspection that most people skip.

Try the key in every way that is not turning it. Push it, pull it, half-turn it, turn it the wrong way, leave it in while moving the shackle.

Work the shackle deliberately. Rotate it, press it down into the body, lift it, twist it. On a surprising number of designs the shackle is the control and the key is scenery.

Change one thing at a time. Because the common failure mode is a sequence lock resetting, random fiddling can pass through the solution without you noticing.

Are Trick Locks Actually Good Puzzles?

The good ones are very good and the market is full of poor ones, so the distinction is worth having.

A good trick lock has a mechanism you can reason about once you have found it, and that you can repeat deliberately. You open it, you understand why, and you can open it again. That is the same standard any sequential puzzle should meet.

A poor one opens by accident. If the solution is a knack that depends on tolerance, on shaking the body, or on applying force at a precise angle you could not have deduced, then it is not a puzzle so much as a lottery, and you learn nothing from solving it. Weight and finish are a reasonable early signal: a solid, well-machined lock usually indicates someone cared about the mechanism too.

The other failing is irreversibility. A lock that is far harder to close than to open, or that can be jammed into a state you cannot recover from, stops being fun quickly. The best designs reset cleanly and invite a second attempt.

Where Do You Get a Good One?

Since we do not make locks, the honest answer is to point you at the people who do it properly, and in this category one name comes up before any other.

Dan Feldman, an Israeli designer, made the DanLock in 1996, and it is routinely described as the best puzzle lock ever built. It is a genuine Israeli-made Nabob padlock altered into a puzzle, and it ships with two keys: one attached to the shackle and one broken.

What makes it unusual is the shape of the challenge. Opening it is reportedly not the hard part. Closing it again is, and that takes several steps. Most trick locks end when they open; this one is only half done at that point, which is a far better puzzle than the usual arrangement.

The collector Edward Hordern owned more than two hundred puzzle locks, and is said to have remarked that if he could keep only three, the DanLock would be one of them, alongside two antiques. That is about as strong a verdict as this field produces.

The work continues at Puzzlocks, now run by his son Boaz Feldman, which makes original locks rather than reissues: the LoopHole and the B-Lock II at the gentler end, Locus a step up. These are the designs worth starting from if the category appeals.

What Do We Make That Is Like This?

No locks. What we make is the same sequential logic in other housings.

Key and Keyway Cube is the closest by some distance: a key, a keyway, and a release that is not where you expect, with a walkthrough. For the hidden-release family, Secret Box and The Quiet Box work the same way, and the wider form is covered in the puzzle box guide.

We have no dedicated shelf for boxes, so the whole range sits in mechanical puzzles.

Frequently Asked Questions

What is a trick lock?

A padlock built so the obvious method fails. The keyhole may be a decoy, a hidden pin or panel may need releasing first, or the key and shackle may have to be operated in a particular sequence.

How old are puzzle locks?

The earliest surviving Roman puzzle locks date to the 2nd century BCE, and puzzle locks with exposed keyholes were widely used in ancient China. Egyptian wooden pin-and-bolt locks are older still.

Did Theodorus invent the padlock 6,000 years ago?

No. Theodorus of Samos lived in the 6th century BCE, about 2,600 years ago. The 6,000-year figure appears on several retail listings for trick locks and is wrong by more than a factor of two.

How do you open a trick lock?

Inspect every face first for seams, rivets and studs that move, before touching the key. Then try the key in every way other than simply turning it, and work the shackle deliberately by rotating, lifting and pressing it. Change one thing at a time, because sequence locks reset silently.

Is a trick lock the same as a puzzle box?

The logic is the same and the housing is different. Both are opened by finding a sequence rather than applying force. A puzzle box holds something; a trick lock usually secures nothing and exists to be opened.