Sargent & Greenleaf 6700 change index problem

[hzatorsk]

...Now begs the question why have a change index, surely less change mistakes would happen if all locks could change on the open index. I guess there would be a simple answer for this too.

Thanks all for your help on this one.

Well... your right! It is common enough for mistakes to occur, that SG devotes page 18 of their Combination Lock Training Booklet to deal with (recover from) the mistake. Using a zero change index lock, it is unlikely a mistake would occur during a combo change.

You'll find the doc on the same site as the previous link I posted. ...and is a must read for anyone truly interested in how these locks work. Any info BEYOND the content of this document would likely be an advanced topic for the secured forums.

Z

[foo]

Because you need that extra part to stop the lever arm dropping in on every revolution whilst changing the combo. It can cause problems.

Bingo.

The extra part Al is referring to is the large sliver colored thing that's on top of the wheel pack.

Most locks don't have this part, and the lever nose is kept out of the drive cam by the mis-aligned gates.

In your case, the silver bit rests on the change key durning combination change. The lever nose can't grab the cam because it's suspended by the bent tab in the middle of the silver thing.

Combination change manual for your lock: http://xrl.us/hjaf

Perhaps the reason your lock has a change index is that dial rings for zero change locks are hard to find? In fact, I don't even see one in the current S&G product catalog: http://xrl.us/hjag

/foo

[foo]

Combination change manual for your lock: http://xrl.us/hjaf

Oops, I just noticed that hzatorsk posted this information previously.

[foo]

Now begs the question why have a change index, surely less change mistakes would happen if all locks could change on the open index. I guess there would be a simple answer for this too.

I just stumbled onto this simple answer last night. From LSS:

The combination in a zero-change lock can be reset without knowing the original number sequence. This can be accomplished without the knowledge of the owner of the safe. The countermeasure is to utilize a regular change lock.

Of course, this same attack is possible with a regular change lock too, but it's complicated by the fact that you'd have to peer through the change key hole, and that you'd need solid knowledge of wheel geography to pull it off.

It seems to me that the best bet (for a safe that has to stand open) is to actually lock it open. I can't imagine that would be a popular procedure.

/foo