by amo » 8 Oct 2025 2:22
My friend has an old Diebold safe with a combination lock. He's lost/forgotten the combination. I've picked a very few padlocks and a couple of door locks and watched videos of the lockpickinglawyer et al. but I'm not very skilled but I fooled around with it trying his best uncertain recollections of what the combination might have been. I see now I can't upload an image of a similar safe but I will find a link later.
I was unsuccessful, but I do kind of feel I must have gotten something right at least once. Since then I've read and downloaded some of the material online and paid my $3.00 for Sophie's spectacular safe simulation. And bought an S and G 6730.
So I'm looking forward to trying again. He lives in a distant town so I don't know when I'll get another shot at it, in the meantime...
I was thinking of ways to make it easier and not so tedious. Someday I'd like to build an autodialer but I was also thinking of other ideas. One that I had been considering is attaching a laser to the dial, perpendicular to the spindle, so that it puts a spot on the wall some distance away. You could mount small solar cells or photodiodes on the wall (or other target) and program something to at least read out fractional number changes in the contact points. I imagine lots more could be automated with this hardware arrangement.
The simulator program has a gyroscope mounted on the dial. Is that a real thing?
So, what follows is a plan to build a safe cracking technological thing. I doubt it would work. It measures the friction of the turning wheel by strain gauges attached to the dial. THIS SYSTEM WAS DESIGNED WITH HELP FROM AI! If you don't want to look further then good for you. I composed this by way of Google's Gemini ai chatbot. It took many iterations and much discussion. My apologies to anyone offended by ai.
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Project Summary: Wireless Torsional Friction Sensor for Safe Manipulation
This project automates the sensitive process of safe manipulation by converting the lock's internal frictional changes (torque) into a precise, wireless digital signal. The key is isolating the subtle "dip" in required force when a wheel's gate aligns, compensating for human inconsistency.
Project Parts List
Component Quantity Notes
Microcontroller (with Bluetooth) 1 ESP32 Dev Board (Recommended for speed/wireless).
Amplifier/ADC 1 HX711 Load Cell Amplifier Module (Provides 24-bit precision).
Strain Gauges 2 Small Linear Foil Gauges (∼0.25 inch grid, 1000 Ohm preferred).
Precision Resistors 2 High-Precision Resistors (e.g., 1% tolerance, matching gauge resistance).
Power Supply 1 Small, lightweight LiPo Battery (e.g., 3.7V) to power the spinning unit.
Mounting Materials Assorted Cyanoacrylate or epoxy adhesive, thin wire, soldering supplies.
Enclosure 1 3D-Printed Housing for the ESP32/HX711/Battery (must fit central knob).
Step-by-Step Project Instruction
Step Action Key Detail
1. Enclosure Design (Design Issue) Design and 3D print the housing. Must rigidly mount to the central knob. Must include channels for thin wires to the gauges.
2. Surface Preparation Clean and prepare the 0.5-inch flat annular region. Use acetone/alcohol, lightly abrade the metal, and clean again. Surface must be pristine for bonding.
3. Gauge Bonding. Bond the two linear strain gauges (G1 and G2). Use a 45∘ orientation to the dial's radius to measure torque. Place them close together for temperature compensation.
4. Final Wiring Solder thin wires to the gauge tabs and route them to the central housing. Secure the wires to remain flat, light, and unobtrusive, connecting to the HX711.
Phase 2: Electronics and Code Setup
This focuses on the high-precision amplification and wireless data transmission.
Step Action. Key Detail
5. Circuit Assembly Wire the Wheatstone Half-Bridge to the HX711. G1 and G2 are connected to the precision resistors (R3,R4) to form the bridge, which connects to the A+ and A− pins of the HX711.
6. Wireless Integration Connect the HX711 to the ESP32. Connect DOUT/SCK pins to digital I/O pins on the ESP32. Mount all electronics securely inside the 3D-printed enclosure.
7. Transmitter Code Program the ESP32 (Transmitter). Code must: a) Apply a Rolling Median Filter. b) Implement Dip Alarm Logic (LED/Buzzer). c) Transmit the filtered data via Bluetooth Serial.
8. Receiver Setup Set up the logging software on the Windows 10 Laptop. Connect to the ESP32's virtual COM Port. Use a terminal program or script to log the incoming friction data to a CSV file.
Phase 3: Manipulation and Data Analysis
This is the procedure for solving the combination, isolating one wheel at a time.
Step Action Key Detail
9. Initial Zeroing Power the system and perform a zeroing calibration. Execute the OFFSET function in the code to establish the stable friction baseline when the dial is stationary.
10. Solve Wheel 3 (Outermost) Sweep CCW 4+ times to clear, then Sweep CW slowly. The first dip and alarm found belongs to the 3rd Wheel. Stop and manually record the number.
11. Solve Wheel 2. Set the 3rd wheel's number. Then Sweep CCW 3 times to clear, then Sweep CW slowly. The alarm/dip now reveals the number for the 2nd Wheel (the first gate is aligned). Record this number.
12. Solve Wheel 1 (Innermost). Set the 3rd and 2nd numbers. Then Sweep CCW 2 times to clear, then Sweep CW slowly. The final alarm/dip reveals the number for the 1st Wheel. Record this number to complete the combination.
13. Data Analysis Analyze multiple sweeps. Run the search sweep multiple times and superimpose the charts on your laptop. The true friction dip will align on all attempts, while random noise will not.
