Lockpicking – Beyond the Basics – Tension Tricks

This is part 3 of the series, where I’ll be covering tension techniques. You can read the previous article on locks here. This one is rather shorter than the other articles in the series, which I’m sure will come as a relief to some!



Types of Tension:

I’m going to start by talking about the advantages and disadvantages of the two most common approaches to applying tension. Those methods are the confusingly labelled Bottom of the Keyway (BoK) and Top of the Keyway (ToK) tensioning methods. They’re unhelpfully not actually relative to the orientation of the lock you’re working on, so I’ve provided a helpful diagram for once, to show you where they refer to:

A euro cylinder with top of keyway and bottom of keyway tension points marked on it

(Original picture from catalocks.eu)

The key is to remember that ToK tension occurs in front of the pins, whereas BoK tension happens on the opposite side of the core, away from the pins.


BoK tension is useful for raking, because the tensioner won’t get in the way, unlike when using ToK, where you’ll find you’ll be ripping your tensioner out routinely while raking. (Read this for my thoughts on raking)

It also lets you clearly see the first pin in the lock, which I’ll get into explaining more about in the next article in this series.

BoK does take up more space in the keyway than ToK, but if you’re working with a tight keyway with a lot of warding, sometimes there’s no disadvantage to using BoK, since you’re not taking up useful space you could move your pick through anyways.

The one thing to watch out for is that when using BoK tension, it’s vital that the tensioner makes contact only with the core of the lock. It’s possible for the tensioner to end up pressing against the housing, which then doesn’t provide a rotational force on the core, and so you’ll find that either the pins don’t bind, or they don’t behave the way you expect them to. If that’s the case, then check that your tensioner is really only touching the core.


By contrast, ToK will give you the most space to work in a lock, since it doesn’t take up any space you’d ever normally move a pick into. It also means you’ll always be applying tension properly.

It’s worth noting that you’ll probably get slightly different feedback from the same lock, depending on the method you’re using, so remember to practice using both.

Other Methods of Tensioning:

So now that I’ve covered the two you probably already knew about, let’s talk about three that you might not have;

1. Ucof’s tension trick:

I first learned about this trick from Autom8on, who attributes this to a certain Ucof from UKLS. This method of tension takes advantage of the locks which have a slot cut vertically down the core to support the key. This shallow slot actually provides two surfaces to tension off, if you can make or find a tool which can grip them.

A euro cylinder being tensioned from the key support channels

This tension trick has most of the advantages of BoK and ToK tension, but it’s probably not going to be a very solid hold for attempts at raking.

2. Cut Down Keyblank Tensioner

Two universal keyblanks connected to make a tensioner
Don’t use universal blanks like I did!

Although this is more common for lever locks, you can do this for pin tumbler locks. You don’t need to use a blank, you can modify an existing key too.

This functions effectively as a perfectly fitting BoK tensioner. In theory, it should be a perfect fit, and give excellent tension control. However, my advice with this – since I’ve made one and used one – is not to use a universal blank, since they never fit nicely, which defeats the whole point of them. Also, these will take up more room than any of your other tension options, so in lots of cases, it’s not much help.

3. Falle-style Tensioner

Falle-style tensioner by b0redstudent
Falle-style tensioner by b0redstudent

Although I’m yet to see anyone who uses a lockpicking set made by John Falle with it’s very unique tensioners, I think they’re definitely worth a mention. Falle tensioners are designed so that they simultaneously tension ToK and BoK, and are adjustable to fit the keyway you’re working with. I’ve not used one, but again, this will give you the benefits of both ToK and BoK tension.

There are templates available online (with a little digging) to allow you to make your own, if this is something that you want to try out. The one above was made by b0redstudent from the Lockpickers United Discord server using the handles from two rakes.

Final notes:

Finally, I’d just like to mention a few remaining things to do with tension. A wide variety of tension options is vital, especially when dealing with higher quality locks. Especially if you’re hoping to tackle higher security locks, you’re going to need to have excellent tension control to tackle locks that use sidebars and countermilling such as found in Assa cylinders. In these cases, the locks often won’t counter-rotate by themselves when you press on the binding pin, and so you’ll have to manually counter rotate the core. If you don’t have an excellent fit with your tensioner, you’ll have a small period as you switch which direction you’re tensioning in, when you have no tension being applied at all – unless your fit is perfect. One option, as crazy as it sounds, is to add in another tensioner. Here’s the first time I saw this being done!

One useful thing to remember is that the binding order for a given lock changes in all but the most contrived theoretical scenarios when you change the direction of tension. If you’ve been having problems getting a lock open tensioning it clockwise, try anticlockwise and vice versa. (Although, please remember that you don’t have this freedom with most padlocks)


So, that concludes this much shorter article! Hopefully you learnt some new things, and hopefully I’ve not made any horrendous, glaring oversights. As always, thanks for reading. Next week, I’ll finally be covering my tips for actually picking locks!

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