Hello, I may very well be demonstrating my ignorance with this question, but here goes.
I am engaged in a rather odd project and I am looking for a tool that would assist me with it. The project is to decode an unknown combination to a high security padlock. Don’t worry, I’m not a criminal! I am active in the locksport community which means that I pick locks and open safes as a hobby, and perhaps someday, competitively. The specifics of the project are, that I wish to discover the combination to a Sargent and Greenleaf 8088 high security padlock. This little beast is essentially a miniature safe-lock housed in a padlock body. Back in the 50’s and 60’s the US government used them on file cabinets containing classified and top-secret documents but they were disallowed at some point because they weren’t resistant enough to destructive attacks. Nevertheless they are considered very secure from non-destructive methods of opening to this day. I bought one without a known combination off ebay for a few bucks and have developed a theoretical method of manipulating it open. A few other people in the community have also proposed this method but I am not aware of anyone that has actually made an attempt to do so and documented it.
So that brings me to the metrology aspect of the project. What I need to accomplish is to apply a fair amount of force to the shackle such as one would do by grasping the padlock body with one hand and the shackle with the other hand and tugging (perhaps 20lb’s of pressure?). Then, without changing the pressure, I need to take a fairly accurate measurement of the inside “diameter” of the space between the shackle and the body. The key is repeatability. I need to apply a fairly consistent degree of pressure (though it anything can vary, it’s this factor more than others) between the shackle and the body, and take a measurement of the exact same spot on the shackle and the exact same spot on the body each time. I may need to do this several hundred times. The degree of accuracy I need is probably on the order of 1/32 inches or ½ mm. After each separate reading, I then need to remove the pressure to adjust the lock for a new reading.
I’ve already looked at calipers, but nothing I saw looked like it could withstand the pressure I need to apply. I’ve also looked at micrometers, but I’m not sure about their capacity for handling pressure either and I don’t want to drop hundreds of dollars on this project just to find out it won’t work either. The tool I imagine in my mind would be perfect would look like split-ring pliers with a dial indicator attached, but no such tool seems to exist. What I’ve decided will probably work best at this point is a hand vise to apply pressure and hold the lock steady, and a caliper to take the measurement. However, this is not ideal because the introduction of a second tool increases the likelihood of inconsistent measurement and increases the amount of time it takes to take each individual measurement. That time sure adds up when you’re taking hundreds of measurements.
So, my question is: Does anyone have a better idea than the one I just outlined? Thanks very much in advance for any assistance anyone can give me here.
I am engaged in a rather odd project and I am looking for a tool that would assist me with it. The project is to decode an unknown combination to a high security padlock. Don’t worry, I’m not a criminal! I am active in the locksport community which means that I pick locks and open safes as a hobby, and perhaps someday, competitively. The specifics of the project are, that I wish to discover the combination to a Sargent and Greenleaf 8088 high security padlock. This little beast is essentially a miniature safe-lock housed in a padlock body. Back in the 50’s and 60’s the US government used them on file cabinets containing classified and top-secret documents but they were disallowed at some point because they weren’t resistant enough to destructive attacks. Nevertheless they are considered very secure from non-destructive methods of opening to this day. I bought one without a known combination off ebay for a few bucks and have developed a theoretical method of manipulating it open. A few other people in the community have also proposed this method but I am not aware of anyone that has actually made an attempt to do so and documented it.
So that brings me to the metrology aspect of the project. What I need to accomplish is to apply a fair amount of force to the shackle such as one would do by grasping the padlock body with one hand and the shackle with the other hand and tugging (perhaps 20lb’s of pressure?). Then, without changing the pressure, I need to take a fairly accurate measurement of the inside “diameter” of the space between the shackle and the body. The key is repeatability. I need to apply a fairly consistent degree of pressure (though it anything can vary, it’s this factor more than others) between the shackle and the body, and take a measurement of the exact same spot on the shackle and the exact same spot on the body each time. I may need to do this several hundred times. The degree of accuracy I need is probably on the order of 1/32 inches or ½ mm. After each separate reading, I then need to remove the pressure to adjust the lock for a new reading.
I’ve already looked at calipers, but nothing I saw looked like it could withstand the pressure I need to apply. I’ve also looked at micrometers, but I’m not sure about their capacity for handling pressure either and I don’t want to drop hundreds of dollars on this project just to find out it won’t work either. The tool I imagine in my mind would be perfect would look like split-ring pliers with a dial indicator attached, but no such tool seems to exist. What I’ve decided will probably work best at this point is a hand vise to apply pressure and hold the lock steady, and a caliper to take the measurement. However, this is not ideal because the introduction of a second tool increases the likelihood of inconsistent measurement and increases the amount of time it takes to take each individual measurement. That time sure adds up when you’re taking hundreds of measurements.
So, my question is: Does anyone have a better idea than the one I just outlined? Thanks very much in advance for any assistance anyone can give me here.