GPO AB Coinbox Mech Key - UK Vintage Radio Repair and Restoration Discussion Forum

BigClick · 25th Mar 2016, 11:50 am

Hi folks,
This is a little success story that might be of interest to the telephony types.

Having tried and failed to source the correct key for the mechanism cover of my AB pre-payment coin box I decided to make one.

I tried and failed to pick the lock because I didn’t have a clue about the lock type or how many levers / pins it had. Now I have seen it I know it is a four-lever mortice lock and I should have used a "curtain pick" (internet research)

The first action was to break into the box in order to remove and dismantle the lock.

By turning the box upside down a 2"x3/8"x3/16” strip of steel can be seen through the cash box. This is what secures a similar steel strip inside the mechanism to secure the bolt.

Slightly raised from the strip are the ends of two 6ba screws, the heads are inside the mechanism.

I applied some force against the strip inside the cash box with a large screwdriver and it did have some movement. So, I made a small groove in the ends of the screws with a tap on a chisel and used a watch screwdriver to turn the screws back through the bar. This worked to a degree but they stopped turning after several revolutions. I decided to drill them out with a 3mm HSS drill and this was very easy.

Once the cover was off I removed the lock and noted that the lock code was 39CB. I could have stopped at this point and tried again to source a key armed with the correct suffix, but I didn’t. I got a blank house key from a key cutting booth for £2 and set about making a key.

I am amazed but it only took about an hour using some needle files I got from Aldi for about a pound.

As well as the four levers there is the section of the key that moves the bolt and a small cut that allows the key to move in the lock but doesn’t allow it to be removed except when in the locked position.

25th Mar 2016, 11:50 am	#1
BigClick Hexode Join Date: Dec 2015 Location: Walsall, West Midlands, UK. Posts: 327	GPO AB Coinbox Mech Key Hi folks, This is a little success story that might be of interest to the telephony types. Having tried and failed to source the correct key for the mechanism cover of my AB pre-payment coin box I decided to make one. I tried and failed to pick the lock because I didn’t have a clue about the lock type or how many levers / pins it had. Now I have seen it I know it is a four-lever mortice lock and I should have used a "curtain pick" (internet research) The first action was to break into the box in order to remove and dismantle the lock. By turning the box upside down a 2"x3/8"x3/16” strip of steel can be seen through the cash box. This is what secures a similar steel strip inside the mechanism to secure the bolt. Slightly raised from the strip are the ends of two 6ba screws, the heads are inside the mechanism. I applied some force against the strip inside the cash box with a large screwdriver and it did have some movement. So, I made a small groove in the ends of the screws with a tap on a chisel and used a watch screwdriver to turn the screws back through the bar. This worked to a degree but they stopped turning after several revolutions. I decided to drill them out with a 3mm HSS drill and this was very easy. Once the cover was off I removed the lock and noted that the lock code was 39CB. I could have stopped at this point and tried again to source a key armed with the correct suffix, but I didn’t. I got a blank house key from a key cutting booth for £2 and set about making a key. I am amazed but it only took about an hour using some needle files I got from Aldi for about a pound. As well as the four levers there is the section of the key that moves the bolt and a small cut that allows the key to move in the lock but doesn’t allow it to be removed except when in the locked position. Attached Thumbnails