Chubb Wall Combination Safe Unlocks but won't lock

[Toadstool23]

Hello and thank you for looking.

I bought this Chubb wall safe second hand as 'working' which it did...sort of.
It is a Chubb SN: WS2 12H 37 025.

The previous owner shipped it locked open and did not know the code but it came with the key and manuals.

Removing the back plate I found all three wheels were alligned at 38. That is, when you reset all spindles (rotate left x4), and stop at 38, the fence drops in and the safe opens and closes fine. Someone with a bad memory was running the safe on a single no, which I did not know you could do!

It seemed to have a lot of crud inside and the lubes were dried up. So I stripped it down but did not remove the wheels.

I then set (using the key), a new 3 digit combination. When I dial in the combination though, the safe unlocks. However the fence gets trapped in the gates of the wheels and the lever nose does not get driven out of the drive cam?

The one thing I changed was the position of the drive cam. I found the drive cam pinned into slot 'L' (as pic) while now it is in slot 'U' (as pic).

The reason I did this was because the dial was scraping on the face plate. When screwing the spindle back into the drive cam I wanted to give the dial more clearance- which it has done. Though maybe this has created the problem with the lock?

I trust that I can, should I need to, open open the lock and with the key reset the combination. Does anyone know what I should do next?

[Raymond]

From your picture, the lock bolt projects to the right. Therefore, the spline key should be in the "R" slot on the drive wheel.

You can always put a shim washer under the dial to create more clearance and still keep it snug. But you might have to unscrew the dial back to the next "R" to maintain clearance.

I can only wonder if there is a 'forbidden zone' issue. Also one of the wheels might be dragging on another just enough to move it out of line when opened. Also a fly may be worn or dirty to the extent that it is not exactly on the selected number. Try removing the lever and dialing the combo to verify if the wheels are stopping where they are supposed to. You may need to remove, clean, and lube the wheels.

? Add a touch of light grease to the nose of the lever where it contacts the drive wheel. Is the cutout ramp on the drive wheel smooth or does it have a 'wear' dent?

[Squelchtone]

I can only wonder if there is a 'forbidden zone' issue.

same here.

[billdeserthills]

I can only wonder if there is a 'forbidden zone' issue.

same here.

I always thought that the missing numbers area on the dial was supposed to account for the forbidden zone

[Squelchtone]

I can only wonder if there is a 'forbidden zone' issue.

same here.

I always thought that the missing numbers area on the dial was supposed to account for the forbidden zone

I would think the same, but what about when the spline key is 90 or 180 degrees out of phase with the orientation of the lock vs which spline the cam is keyed to?

[billdeserthills]

'The reason I did this was because the dial was scraping on the face plate. When screwing the spindle back into the drive cam I wanted to give the dial more clearance- which it has done. Though maybe this has created the problem with the lock?'


Did you remove the dial and see if the scraping faceplate can be adjusted?

[Toadstool23]

Many thanks to you all for commenting.
It is so very life affirming when strangers with a shared interest offer help.

It is now working fine.
Some notes on how/what I learned....

I took lots of pics on the 'way in' and can confirm that it was opening and closing smoothly enough when I got it but with dialling only one number. I guess this is achieved through entering the coding key, dialling the pack only one way to the first number, before removing the coding key, leaving you with a one digit combination?

Anyway, the spline pin was set to left (L) position when I first opened it up, but did not foul up the locking and unlocking.

Looking for some more clearance (and not knowing the meaning of the letters!) I set the spline to 'U'. I have since set it to R so thanks to the person who advised me to do so, as it not works! So perhaps comments about 180 degree positions being equal may be right, but 90 degrees out definately fouls the fence in the gates when the lever is moved by the cam drive.

The forbidden zone: Pretty sure as comments that the numberless area on the dial resolves this matter for this particular lock as the manual gives no restrictions for the choice of numbers (but does advise not to use ending in 0 of 5, presumably for avoiding 'obvious' combinations?)

Many thanks again All.

[Toadstool23]

'The reason I did this was because the dial was scraping on the face plate. When screwing the spindle back into the drive cam I wanted to give the dial more clearance- which it has done. Though maybe this has created the problem with the lock?'


Did you remove the dial and see if the scraping faceplate can be adjusted?

Many thanks for replying.

I did remove and clean up the face plate. It looked to have some wiggle room, yes, and I set it by eye concentric with the main hole through the safe door. I have since watched a video online where a guy suggests using a plastic mallet to knock the face plate across(?) the face of the door. I will take advice and likely pack the dial outwards with a washer, allowing it to stay snug.

[Toadstool23]

......You can always put a shim washer under the dial to create more clearance and still keep it snug. But you might have to unscrew the dial back to the next "R" to maintain clearance.

......Also a fly may be worn or dirty to the extent that it is not exactly on the selected number.

..... You may need to remove, clean, and lube the wheels.

..... Is the cutout ramp on the drive wheel smooth or does it have a 'wear' dent?

Many thanks Raymond, your questions answered..-ish!

Shim washer- thanks, sounds ideal. Must this be brass? Can I make one from plastic?

Fly being worn- no idea what a fly is. Presume it's something within the wheels that plays a part in the coupling/decoupling process actuated via the coding key?

Removing and cleaning and lubing the wheels- I was scared to, so didn't go in so far as to remove them. I regreased parts that had old dried grease on but left other parts that looked clean/dry, i.e. brass on brass. What should I clean and lube the wheels with? And are there any disasters I need to avoid in their removal and refitting?

[Toadstool23]

A final answer on the positioning of the spline pin. I.e. for my model of safe (see original post at top) spline pin options are U, L, D, R.
The R and the L are NOT interchangable. Mine only works with R.
I am now convinced that the safe came to me set for a single digit as a workaround for their problem with the fence getting caught in the gates. A 'lock out' situation. Presumably they did not know it was due to the spline pin being wrongly set to L.


I have taken the workings out of the safe box and stripped the paint off and repainted it.

In reassembling, I took the suggestion of someone above and added a brass shim to cure the dial rubbing on the back plate. It was actually an old brass backplate (sits between door knob and door) I have in the shed which beaten flat, cut down, sanded and polished, has made a good enough shim albeit quite thick. The tolerances are quite small. Too much taken up with shims and the dial is stiff, not enough and it wobbles and causes the dial to scrape the back plate. This with the two already in there was too thick. With one original pair and my new one it made the dial too tight so I have only my home made shim in there... is this ok? Must there be at least 2?

Why are there not more things in my home I can cannibalise that are very thin and made of brass!?