BlockGuard

[bumpit]

http://www.masterlock.com/school/blockguard/

In my opinion one of the worst locks in the market. Anyone here try shimming one of these "Shim Proof" locks? If they actually are shim proof it is going to bring tear to my eye....

The model numbers on the new blockguards are 1502 and 1525. Let me know people


Bumpit Out,

[thelockpickkid]

I have done a little bit of research on this, and from what I can tell, it is only on the combo locks that have a key override on the back, if this is the case, it's real easy to pick these!

[tjweaver84]

the brochure and video say it is available on both the one with the key and the one without.

[raimundo]

this lock does not appear to be unshimable, its only defeating the commercial 'butterfly shims that are inserted opposite the locking dog and rotated to push it back,

I make shims out of a type of hard stainless spring found inside some vhs tape cassettes. this is a flat spring that is fused to the plastic case and prevents shake and vibration of the reels.
this spring comes in variants that are of different widths and thicknesses from different tape cassette manufacturers.

cut a piece of this to about an inch and a half, including one end of the spring, there should be a slight machine formed bend in this, the part that has the natural rounded end of the spring is the handle, grip this in a locking pliers, and hold the other end that you cut off with tinsnips, over a block of relatively soft wood, (pine) get someone else to hold the shaft of a screwdriver just above the piece of flat steel and strike the shaft of the screwdriver hard with a hammer, this will drive the shaft into the piece of spring and the spring will sink into the pine, while taking the rounded profile of the screwdriver shaft on the end that is forward of the slight bend,

next, use the tinsnips to cut the rounded end to a shape like a clip point knife blade,
with the tip optimised for comeing at the lock from the front, (its a left - right thing, figure it out, if you get it wrong, it will still work from the back of the lock. file the burr off the tinsnip cut and smooth the edge of the shim with just a few swipes on a piece of rough sandpaper

This shim is not used by inserting on the easy side of the shackle and then rotating it to the locking dog,
This shim is bent to about a 90 degree angle at that original slight and the curved clip point is pressed into the shackle hole directly above the locking dog and comes right down on top of it, moving the dog back during insertion.

It may seem that it wont fit, but if you can get the point down in, the hardened shackle still has enough flex to push away just a few thousandths and you can force the shim down in, on the top, cam surface of the locking dog. The sanding off of the burr will be very important if the space is tight, the burr carries friction that works against cam ing the surface back,

Insert the shim so that the clip point is just off the edge of the locking dog and as you press it in, its the curved edge, not the point that is cam ing the dog back.

typically you press this in and as you do the shackle is pressed in a few millimeters, then you press on the handle of the shim while pullling the shackle out again, keeping the shim is far in as possible, then press the shim and shackle back down, this allows the shim to get in further, its when the shackle will flex to accomodate it,
again, pull the shackle out its few millimeters, while refusing to allow the shim to pull back, and again push shackle and shim in together, by this time, typically, as you pull the shackle back, the shackle will open.

There are some others here who have seen these shims and know what Im talking about, if anyone has photos of one, (its been a few year since I was sending them out to people, don't know if the people are still here and if anyone still has one of these shim, but a photo would be nice if you do, I don't post photos, computers don't like me.)

[Solomon]

The patent is still pending, and these have been available since january... that rings alarm bells, then again I don't know anything about how long patents take to go through. I watched the video, and it looks like this is a good solution to standard shim attacks, as a matter of fact with a standard shaped shim I'd definately agree it isn't possible. Like raimundo said though, a simple modification to the regular shape is all that's required. It may damage the latch slightly, but only scratches. It certainly wouldn't do anything to the mechanism.

So, Masterlock comes up with an ingenious new latch to prevent shimming, and we cut a little section out of the shims which renders it pretty much obsolete. Wonderful. Hopefully the bad guys won't realise this.

[straightpick]

After watching the video it appears that it will still stop the top dowm shim attack proposed by raimundo. The dog has two notches in it that will catch the shim and prevent it from going any further, bending the tip of the shim in the process. Just an observation.