Considering an automated rig to open an old Star floor safe

[bentwookie]

Hi everyone. Our house has an old floor safe and nobody (living anyway) knows the combination. A few years back I did some research and discovered that any combination on file with the safe company was lost in a fire.

In the years since, I've gotten pretty good at building interesting mechanisms with servos and 3D printers. I thought a fun little project would be a robot that tries every combination until the safe pops. At 20 seconds per attempt, it will take around 230 days.

Spinning the knob and watching the ticks go by is easy enough. Am I correct in thinking that the process is:

Spin 4 times to the Left (ending at a number)
Spin 3 times to the Right (ending at a number)
Spin 2 Times to the Left (ending at a number)

Then comes the tricky part (automation wise)

Push the knob down and then dial clockwise until the lugs retract.

My big fear is missing the successful entry of the combination. To that end, my initial idea is to keep constant upward tension on the handle while manipulating the dial. When correct sequence is triggered, the lid should pop.

Some questions:

• Will applying a constant upward force cause problems with the unlocking sequence?
• After pushing the dial down, how many degrees of clockwise movement are required to retract the lugs?
• Are there any techniques (listening, feeling, etc) that can help me limit the combinations to try?

Thanks for helping me explore this problem! Here's a picture of the safe in question:

[billdeserthills]

Your picture linky no worky,
I will assume you have an old round Star safe with a lift-out door
I have opened many of these and also rebuilt and returned several into service
sometimes when these sit for a long time without use, the fence tends to get stuck and doesn't
want to engage, even when the wheels have been dialed correctly.

As for 'upward tension' upon the dial, perhaps you are unaware of this, but the Star dial is normally
able to be lifted off of the spindle. I expect if you apply enough pressure, yours will also lift off

I don't spend a lot of time manipulating the safes I do open, I like to drill and scope

[bentwookie]

Oops! I'll try the picture again.

To put tension on the lid, I was planning on lifting the wire handle instead of the dial itself. Interesting point about the innards not working after who-knows-how-many-years of non-operation!

That's cool to hear that you can drill them and poke around. I was wondering if after you drilled one, you were able to rebuild them. Something to consider on day 231 after this all goes sideways!

[femurat]

Something to consider on day 231 after this all goes sideways!

I like your sense of humor.

Here is an article that may be of interest for you, even if your safe is completely different. https://www.wired.com/story/watch-robot-crack-safe/

Good luck with your project

[billdeserthills]

The Star safe you show in your pic isn't very old
you prolly won't have the 'sticky fence' problem I described

I would think applying a constant upward force will make withdrawing the bolts/lockwork more difficult
these safe heads are fairly heavy

[Raymond]

Your scheme will probably work. On the last turn to the right, program your dialer to move to '0', stop, and then push in, and hold in while turning right. If the dial stops in about 5-15 numbers, its open. If not, dial the next number.

[bentwookie]

That would make the mechanism way easier. It seemed rather non-deterministic to me when you could push down and when it wouldn't let you. It doesn't have to be positioned at the last number when you push it in? It's ok to go backwards (or forwards?) to 0?

Thanks for the replies everyone!

[Lelandwelds]

Nice!

[Raymond]

NO! to the statement:

It's ok to go backwards (or forwards?) to 0?

The dialing sequence is 4-left, 3-right, 2-left, and right to "0", and at this point you push in and turn right while holding the dial in. If the dial ramps back up and continues to turn the first three numbers were not correct. If it turns right and stops, the locking bolts will probably have been drawn into the safe body and the door can be lifted out.