Bumpkey Proofing Locks.

[pickmonger]

I am looking for some easy and inexpensive modifications that can be done to protect some locks from being bumpkeyed.

Dealing with over 100 locks in apartment and offices, the capital expense of installing "offically approved" bump proof locks would be huge.

Some of the suggestions I have been given include:

1) Put a 3rd pin in one of the rows, somewhat like I was master keying .
The hope is that the bumpkey impact would lift only the top pin and the other critical pin would clear the shearline.

2) Strech the springs, replace the existing springs with stronger, or use two springs in one row ....thereby creating more resistance that the energy of the bumpkey can lift.

3) Use pins made of different material ..... given their different weights they would lift at a different rate and would not clear the shearline at the
same time.

Please give any comments pro or con on these suggestions.

[zeke79]

Use a low cut in one of the last 4 positions and do not allow it to drop down fully as the other pins do. This could be done to any standard lock with some machine work. Some lock may be able to be modified easily with only a small grub screw that does not interfere with the insertion of the keyblank yet holds the bump proof pin stack higher than the other stacks. The end result should be that the bumpkey never contacts the modified pin stack as it is held higher than the peaks of the bumpkey can reach.

[keysman]

...Some of the suggestions I have been given include:

1) Put a 3rd pin in one of the rows, somewhat like I was master keying .
The hope is that the bumpkey impact would lift only the top pin and the other critical pin would clear the shearline.

I think that would make it easier .. creating another possibility for a shearline

...
2) Strech the springs, replace the existing springs with stronger, or use two springs in one row ....thereby creating more resistance that the energy of the bumpkey can lift.

If you create more resistance than the bump key can lift , then the user would also have a difficult time using the key. although you may be on to something...

...
3) Use pins made of different material ..... given their different weights they would lift at a different rate and would not clear the shearline at the
same time.

Do you know where to get pins made of other than brass or Nickel plated brass?

I think if you use a combination of different spring strengths, coupled with random security pins … serrated bottom pins and serrated / mushroom top pins you may see some improvement.
You may want to experiment with blocking the back of the keyway so the key can’t enter beyond the last pin position , possibly requiring you to modify the key to fit properly .

Good luck and please keep us informed of your progress

[keysman]

....assuming you could get a steel pin.. how about a magnet for the top pin and a steel bottom pin .. they would stay together and not seperate when impacted, but would seperate when the bottom pin was brought to the shearline by the proper key?

[zeke79]

That's a great idea and I may have some magnets and steel pins to give it a go with. I'll report back if I have the materials!!

****REPORT**** The smallest neo mags I have are 1/8" so its no go there. After thinking a bit though I wonder how well the neo magnets would hold up since they are brittle?

[illusion]

I remember the part from the Shmoocon video which explained the measures against bumping. One part showed extra pin chambers drilled about 20 degrees next to the original holes which contained high powered springs and pins.

When a key with the correct biting enters the lock it pushes the bottom pins to the shearline, causing the lock to open. When you bump a lock you do not raise the bottom pins to the shear line at all, but bounce the top pins up - the effect is the same regardless of whether the bottom pins are raised or not - the top pins are at the sheer line and the plug turns. The biggest difference between the two, is that the correct key keeps the bottom pins at the sheer line whilst turning to unlock, but when picking or bumping there is nothing to stop the bottom pins from dropping down.

When the correct key is inserted in one of these anti-bump locks it raises the bottom pins to the sheer line, and then turns - at which point it meets the 'anti-bump chambers' containing the high powered springs and pins, but since the key is stopping the high powered pins from entering the plug then there is no problem, and the plug turns unhindered. If you have picked or bumped the lock the high powered pins will shoot into the plug and immobilise the lock, since there is nothing keeping the bottom pins at the sheerline..

If you have ever reassembled a lock, and had 3 top pins, but only 2 bottom pins you will know well that the top pin in the chamber that has no bottom pin shoots into the plug and imobilises the lock. The anti-bump mechanics are pretty much identical to this, and you would be reduced to destructively opening the locks, or finding a way to rectify it - I have no ideas as to how this would be done yet.

This would stop bumping and picking, but I am not sure if a Sputnik would be beaten by it - would the wires be strong enough?

I really like this idea, and hopefuly I havent explained it too badly. For further referrence, watch the Shmoocon video.

I guess you could drill the new chambers in lock body , and fill them with high powered springs yourself - I have no idea as to whether this is the best solution, but it will also prevent picking.

Thanks.

[eric343]

ForceField sells 1/16" dia by 1/32" thick neodymium magnets. You could probably bore a hole in the face of the pin for the magnet, and have the surrounding walls take the impact.

[zeke79]

I may give it a go, but I"ll have to see if I have a 1/16" end mill too. It wil be a bit though since I am not really able to work on the milling machine right now. Setting up the pin might be a pain in my vice also.

It may be that if we go down to that small of a magnet that the top and bottom drivers will need magnets to overcome the energy and not allow the pins to separate.

Could be a fun experiment.

[chrisjc33]

I remember the part from the Shmoocon video which explained the measures against bumping. One part showed extra pin chambers drilled about 20 degrees next to the original holes which contained high powered springs and pins.
best solution, but it will also prevent picking.

these are called trap pins they are a good idea to prevent picking and bumping but if anyone gets/makes these trap pins DO NOT try to bump or pick them because the only solution is to drill them out.

and someone talked about using small magnets if you get steel pins and leave them on a strong manget overnight that should do the job.

[mh]

I remember the part from the Shmoocon video which explained the measures against bumping. One part showed extra pin chambers drilled about 20 degrees next to the original holes which contained high powered springs and pins.

I've heard that too, but don't understand it.
What prevents me from bumping / picking the lock a second time at that position?
And what prevents the user from pulling the key out at that position?

Thanks,
mh

[chrisjc33]

I've heard that too, but don't understand it.
What prevents me from bumping / picking the lock a second time at that position?
And what prevents the user from pulling the key out at that position?

Thanks,
mh

when the trap pins trap the plug they under high spring pressure and can't be removed(not tried it myself)
and the user can't pull the real key out because the bottom/key pins are at the sheareline and in the valley of the key and the pins won't move up to ride up and down on the key so it will not come out.

[Gordon Airporte]

Um, guys, can't you just turn the pin itself into a magnet? I would use one of those thingies for magnetizing screwdriver tips - it's two magnets clamped together with a hole between them, about a 1.5" cube. I got mine at Sears.
Bonus: you can magnetize your screwdrivers!

[zeke79]

That would not create magnet that has enough power I dont think.

[Varjeal]

Just thought of something that might be painfully obvious but also painfully easy.....

How about repinning the lock, 'cept in a position or two inserting a ball bearing of proper diameter as the "bottom pin", then making up the remainder of the bitting position with a proper sized pin... One shallow depth and one deeply cut bitting position should do the job.

The "pool-ball" effect might actually drive the "bottom pin" into the shearline, blocking it from turning. Haven't tried it, but just a thought.

[maxxed]

I have an old Corbin lock that uses ball bearings on the bottom, tried bumping it works.