In regard to preventing self impressionism of tubular locks

[JoshuaWest]

Lets start with my understanding of the self-impression technique commonly used with tubular picks to open their respective locks.

It's my understanding that after inserting the tool (with all "feelers" level with the end, under minimal pressure keeping them here) and twisting it, the pins that are over-set have spring tension pushing, and through combination of a repeated binding, small tolerances in the lock, and springs pushing, eventually the pins are pushed to the shear line. At this point, as we know, the pins no longer bind, and therefore do not keep pushing out. (why?)

I seem to be missing some basic understanding as to why the pins no longer push beyond the shear line, do they get caught on the ledge similar to an inline pin tumbler?

How does having varying spring strengths defeat this technique?

If this only works with all springs pushing evenly, then why do the pins naturally stop at the shear line, considering the twisting motion back and fourth would align the driver pins with the key pin perfectly (even if for a moment)

Wouldn't stronger springs just push the pins to the shear line that much quicker?

Thanks!

[billdeserthills]

Actually there is one small detail that you missed. Once the tool is carefully set into the lock with the feelers extended in between of twisting the tool back & forth it needs to be withdrawn from the keyway about 1/4 of an inch. The tumbler springs alone do not have the strength to push the feelers to the required place on the tool, so you must supply the in & out pressure between twistings. I have read that a small spring (like from a disposable click-type pen)inserted into the center of the tool
can be quite a help with the picking speed, but I never got it to work for me.

[JoshuaWest]

The tumbler springs alone do not have the strength to push the feelers to the required place on the tool.

Thanks, I will have to try that next time!



My primary goal for this topic is to understand how the varying springs defeats the technique, but I'm definitely glad to better understand in the first place. (I'm sure the missing step in understanding the defeat)

Unfortunately, ( ) your reply just furthers by inability to understand how different springs would have any effect.

[billdeserthills]

The varying spring tension certainly doesn't make the picking any easier, several companies sell tubular picks that allow you to manipulate the ends of the pin probes. Peterson makes a dandy tubular lock picking tool, but it costs more than I wanna spend, as in my line of work picking a lock is just one of the ways I choose to get it open. I don't mind destroying and replacing if the lock gets uppity and I have quite a good stock of replacements in my truck. I would go into my preferred destructive methods, but I'm afraid it is a topic for the advanced forums. I do recall years ago when Kryptonite was embarrassed after their newest restricted key model of bike locks came out. Turns out the tubular lock was just the right size for a bic pen to fit into the keyway and some enterprising students found that the plastic would, without much work, self adjust to the actual pin heights thereby picking open without much provocation. Poor Ingersoll Rand wound up having to foot the bill to replace every one of the formerly high security Kryptonite bike locks & I hope it cost them a fortune!

One neat thing about picking a tubular lock is afterwards the pick can be decoded & a working key can be cut off the pick!

[EmrysCPennent]

The self impression technique works in tubular locks because depending on the length of the key pin it effects the amount of compression force in the spring. For example take any compression spring and apply pressure. The more pressure you apply the more compressed the spring becomes. The more compressed it becomes the more energy you have to exert to hold it in its current state of compression. So for tubular locks if all the springs are the same length/strength and all the chambers are drilled to the same depth and the driver pins are all the same length then with a long key pin in one chamber it is compressing the spring more(lots of stored energy) where as a short key pin is still compressing the spring but not as much(less stored energy). So the amount of energy(pre-load) in the same length and strength springs varies from pin to pin depending on the length of the key pin compressing the spring. Springs of different lengths and strengths could be applied to essential balance the amount of pre-load pressure/energy on the springs so that they equal out roughly making it harder to impression the lock.

Hope that helps,
Emrys C Pennent

[EmrysCPennent]

Of course I forgot to mention that the tension on the feelers for the tubular pick tools plays a part in that to help counter act/balance the force exerted by the springs, to much tension and the weaker springs can't move the feeler, to little and the more compressed springs and even weaker ones get passed the shear line into there resting positions and you don't get a good impression.


Emrys C Pennent

[critmass235]

i thought the pen way worked bc the bound key pins would deform the pen if turn then pressed in. then during the next turn would the springs try
to push they over setout.but if its set there no spring(weak or strong) to push farther. so wouldn't with right timing and depth control (pull a key depth back in between turns) work? springs are strong enough to push out with no tension

[GWiens2001]

The Bic pen trick worked because the older tubular locks could not be pushed down past the shear line, so the non-moving pins would deform the pen until a key was self impressioned. Most tubular locks these days work as normal pin tumbler locks do - allowing the key pins to be moved past the shear line.

Gordon

[Raymond]

All of these posts do not support the title of this thread. But I will try to clarify what impression picking is.

The Mechanics of Impressioning as Applied to Picking a Tubular Lock

Refer to the pins closest to the face of the lock as the ‘key’ pins. They serve exactly the same function as bottom pins in a normal lock cylinder. The back or top pins serve the same function also. Picking can be made more difficult by use of spools on either pin and lock cut-outs. For this ‘impressioning’ to work, you must understand what is actually happening.

I will presume that there are no solid pins in this example lock. Prepare the pick by pushing all feelers out of the tip a small bit. Set your friction adjustment to medium tightness to begin with. It can be adjusted later as needed. Push the front of the pick against a solid flat surface to set all feelers at exactly the top. The tubular pick must push all pins as deeply as possible to simulate a 0 cut on the key. To begin picking you push the pick all the way in and then draw it back only about 5-10 thousandths of an inch, (1/4" is way too much.) Apply turning pressure and push the pick in to reclaim those 5-10 units. What is happening is that if a key pin is at the shear line it will not bind when turned. If it is not at the shear line and is one of the first to bind due to the turning pressure, the second push will push the feeler back 5-10 units. (The feeler moving back is exactly the same as filing the mark off when Impressioning cylindrical locks with a key blank.) Now repeat the process exactly. Release turning pressure, pull back 5-10 units, apply turning pressure, push the pick back in while turning. Putting a spring inside the end of the tubular pick can sometimes help push the pick back the 5-10 units if the lock is loose and wiggly. Do not wiggle the pick back and forth or you might crack the front end. This is an exact, technical process. Be patient. You can test for lucky combinations by using very light turning pressure and moving the pick in and out. The pattern may be correct or very close with only the depth off and the lock might open. Otherwise, stick with or go back to the exact process. The lock may pick quickly or take several tries with varied friction on the feelers. Watch for a feeler moving out too quickly and increase friction. When the lock turns, be careful to turn it only half way to the next pin or it will lock up again.

With the lock turned, remove the pick. Zero it again and tighten the friction to very tight. Reinsert the pick and push it in all the way. The feelers will move back and form the exact pattern of the key. At this point the pick has actually become the key and can be used to turn the lock back and forth. This is when you must measure the depth of the cuts to determine the true key code. On some key duplicators, the pick can be used exactly as if it is the original key and duplicated onto a blank.

It does not work so well on ACEII locks because of the different spring pressure. Most of these picks apply the same friction to all feelers equally. Therefore one or more of the feelers will simply slide back due to higher spring pressure and not be picked. If the friction is increased too much the feeler will not move back when contacting the pins with weaker springs. There is an Ace type pick on which the friction can be individually adjusted, and it does a much better job of picking these locks. There is also a pick that tightens a collet on the center plug and moves differently. There are a lot of variations so do not expect everything to fit only one procedure. You must be mentally prepared to adapt to changes. Good luck.

[femurat]

Great explanation Raymond, you put it simple and easy to understand, but still accurate.

Cheers

[JoshuaWest]

It does not work so well on ACEII locks because of the different spring pressure. Most of these picks apply the same friction to all feelers equally. Therefore one or more of the feelers will simply slide back due to higher spring pressure and not be picked. If the friction is increased too much the feeler will not move back when contacting the pins with weaker springs. There is an Ace type pick on which the friction can be individually adjusted, and it does a much better job of picking these locks. There is also a pick that tightens a collet on the center plug and moves differently. There are a lot of variations so do not expect everything to fit only one procedure. You must be mentally prepared to adapt to changes. Good luck.

Perfect, This is exactly what I was looking for. Thank you!

I can already think of several ways that these tools are still useful without the using this technique.

Thanks for the input everyone!

[KPick]

I'm sorry to add my biased comment, but lol that must be one hell of a lock. I mean different spring pressures? Awesome! A challenge from Ace!

[GWiens2001]

Different spring pressures is one way that manufacturers have been trying to combat lock bumping. The return rate of the springs varies, so it is tougher to bump.

Gordon