a SHIMple question

[pickersRus]

Ok maybe this is not so simple but can someone please explain to my why you have to place the shim at the rear of a pin tumbler lock when your shimming it open ? Could the same result ( an open lock ) not be achieved by shimming from the front or face of the lock ? I am sure that there is an excellent reason for having to shim from the back but for the life of me I can not figure out why. I have searched for shimming questions and answers but so far have not found anything in these forums or other sources that can explain it so I can understand (I am stupid ). Any answers will be greatly appreciated. THANKS

[randmguy]

You can't usually shim from the front of a lock because the cylinder face has a larger diameter than the hole through the lock body. This is to prevent the cylinder from falling out the back of the lock body. On some incredibly sloppy or worn locks it is possible to get a shim in the front of the lock without it folding up. This is a rarity, however.

[Buggs41]

And you really don't want to allow the lock to be shimmed from the front. That would really defeat the purpose of having a lock in the first place.

[Romstar]

I can't add too much to this really.

That's pretty much the long and the short of the reason.

The diameter of the lock plug's face is actually larger than the diameter of the plug itself. The plug face sits in a recess in the cylinder. This ridge prevents the lock from falling into the lock from the front in much the same way that the retainer keeps it from falling out from the rear.

Romstar

[toomush2drink]

You can use a dremmel to remove this lip and shim it, its a useful way of overcoming a difficult lock.

[Luke]

if i was going to do that, which i have done... i would just drill the plug... it has a lesser chance of damaging the cylinder it self.

[toomush2drink]

True i agree luke but the new yale x5's have a ballbearing to prevent drilling.

[Luke]

Yeah i agree that would be better...
At the end of locksmith course at tafe you have to open a lock in 3 different ways without damaging it... Standards are Picking, back shimming and frontal shimming....

[S3rratedSp00L]

Hmmm... why not harden the whole plug too? Must be a cost thing, huh?

I had a really sloppy kwikset lock that I tried to shim from the front. I got four out of five stacks shimmed and the shim ripped. Luckily, I stuck a pick in and got the last pin, but it was a wierd experiment to say the least Used some thin feeler gauge as a shim. I must say that I have never come across any other lock this sloppy and screwed up in my entire life. It would have been much easier to shim from the back for sure, but it was still in the door. Once I had it open, I took all the pins out and kept them, then threw the rest away. It was that bad! I woudn't even give it away as a n00b practice lock because it would just teach bad habits!

Always shim from the back of the cylinder!

[HeadHunterCEO]

because then you have to advance the key while trying to advance the shim


easier to hold the shim and lock in one hand while using the other to back the blank off