How to Reset a Safe Combination on a Mechanical Dial Lock

Short answer: How to reset a safe combination on a mechanical dial depends on the lock. On locks with an owner procedure, such as Sargent & Greenleaf's 6730 series, you open the door, dial the current combination to the changing index, insert the maker's changing tool, dial the new numbers and remove the tool — then test the new combination three times before closing the door. Some safes can't be changed by the owner at all: SentrySafe's fire safe manual says its dial combination can't be changed, and Liberty sends mechanical changes to a dealer or licensed locksmith. You always need the current combination to start.

This page is about mechanical dial combinations. Keypad codes are a different job — see how to reset a safe code. For dial-locked safes in general, see our combination safes page.

Can a safe combination be changed? Three answers from three makers

The honest answer is "check the lock," because manufacturers disagree.

• Sargent & Greenleaf publishes a full owner-facing changing procedure for its 6730, 6735, 6738 and 6741 mechanical locks. It needs a changing tool that matches the drawing in the instructions, the current combination and an open door.
• SentrySafe says in its Fire-Safe owner's manual, under the mechanical combination lock section: "Combination can not be changed."
• Liberty Safe says you cannot change the combination on its mechanical locks without a certified locksmith, and that the work must be done by an authorized Liberty dealer or a licensed locksmith. Its electronic locks are a different story: owners change those themselves.

So before you buy a changing key online, find out who made your lock and what they allow. The safe's brand and the lock's brand are often different companies. Your safe's manual or its manufacturer can tell you which lock it uses.

How to change a safe combination on a Sargent & Greenleaf dial lock

What follows is S&G's own procedure for the 6730-series three-wheel lock, condensed. Read the full instructions for your exact model before starting. If any step doesn't match what you see, stop and call a qualified safe technician.

Prepare.

1. Open the safe door and keep it open for the whole job. S&G says all changing operations happen with the door open.
2. Check that your changing tool closely matches the outline in the instructions. S&G says the wrong tool will likely cause the lock to malfunction.
3. Never insert the changing tool unless the lock's cover is in place.
4. S&G suggests covering the opening index (the twelve o'clock mark) with a piece of opaque tape, so you only dial to the changing index (the mark near eleven o'clock).

Dial the current combination to the changing index.

5. Turn left until the first number reaches the changing index the fourth time.
6. Turn right until the second number reaches it the third time.
7. Turn left until the third number reaches it the second time.

Insert the tool and set the new numbers.

8. Insert the changing tool until its wing is fully inside the lock case. Don't turn it until it is. Then rotate it about 90 degrees counterclockwise; S&G says you'll feel a definite release of tension.
9. Dial the new combination to the changing index: left to the first new number the fourth time, right to the second the third time, left to the third the second time.
10. Turn the dial right about ten numbers.
11. Rotate the tool about 90 degrees clockwise and remove it. Don't pull on it until it's fully rotated back.

If you think you made any error, however small, S&G says to start again at the "enter the new combination" step.

Check it, three times.

12. Uncover the opening index and open the lock with the new combination, using the normal opening procedure. See how to open a combination safe for that.
13. Repeat. S&G says a change is successful only after the new combination works at least three times. Only then close the door.

The door stays open. The coffee can wait.

Choosing a new combination: S&G's rules

S&G lists five rules for picking numbers that suit the lock's design:

• Not all numbers ending in 0 or 5.
• No ascending or descending sequence.
• At least ten numbers between adjacent numbers of the combination.
• No third number between 95 and 99 or between 0 and 20. S&G says these can stop the lock from locking correctly.
• Nothing easily guessed — birth dates, house numbers, phone numbers.

That fourth rule is the one people break without knowing it. It's specific to this lock. Other makers may have their own forbidden range, so read your lock's sheet.

Safe combination reset gone wrong: what S&G says to do

Mistakes happen mid-change. S&G's instructions have a section for it, and the first instruction is the important one: do not close the safe door until the problem is fixed.

• If the new combination won't open the lock, S&G says to dial the new numbers to the changing index and try reinserting the changing tool. If it goes in fully, turn it and enter the new combination again.
• If that fails, the guide describes a second procedure that involves removing the lock cover. That is technician territory. S&G's own warning: don't remove internal parts, because the lock should only be serviced by a qualified safe technician.

A lock that won't take a new combination with the door open is a service call. With the door closed, it's a lockout.

How to change gun safe combination settings: dial, keypad or conversion

Gun safes split by lock type, not by safe type.

Mechanical dial. Follow the safe maker's rule. Liberty says its mechanical combinations must be changed by an authorized dealer or licensed locksmith. Liberty also notes that mechanical locks have no recovery combination — if you lose it, you need a locksmith, or you can ask Liberty to remove your code from its records.

Electronic keypad. Liberty says owners can change these themselves, with a keypad sequence or on-screen prompts depending on the lock. See how to reset a safe code.

Switching to a keypad. If you change combinations often, a dial may be the wrong lock. Liberty's lock comparison says mechanical locks typically need a professional to reconfigure. Its retrofit article says most of its safes with a mechanical lock can take a UL-listed electronic lock, installed by a locksmith or certified dealer.

Here's the catch: you need the old combination to set a new one

Every changing procedure above starts the same way: dial the current combination. There is no owner reset from a forgotten combination. That's not a missing feature; it's the point. A lock that could be reset without the old numbers would be a lock anyone could reset.

That also means a botched change can lock you out of your own safe. Hence the door-open rule, the three tests, and S&G's capital letters. If you're changing the combination because you've lost it, you're on the wrong page — see locked out of a safe.

One more thing the instructions point out. S&G says all combination safe locks should be serviced by a qualified technician annually. ALOA warns against lubricating a safe lock yourself. If the dial already feels gritty, have it serviced before you ask it to learn new numbers.

Skip it if: when you don't need to change the combination

• Your safe's manual says the combination can't be changed. SentrySafe's fire safe dial is one example. Store the original carefully instead.
• Your safe maker requires a dealer or locksmith. Liberty's mechanical locks, for instance. Call them.
• You don't have the current combination. See locked out of a safe.
• Your lock is electronic. See how to reset a safe code.

That's the job. Confirm your lock allows an owner change, use the maker's tool, keep the door open, and test the new numbers three times. Then write them down somewhere that isn't the safe, and take the old combination off the sticky note.