Vise jaws for spreading work apart?

[chevydyl]

The op said it takes very little force to do what he wants, doesn't sound like he wants to break the lock just move it like you can with your hands, but it needs to be very accurate, make your own jaws that will screw into your vises jaw holding screw holes, like L shaped facing opposite directions. Make em outta something hard like 4140 so they don't flex and give false readings. I can draw a picture up later if you don't understand what I'm suggesting.

 

[kd4gij]

Can you scribe the side that doesn't come out at the base then open the lock all the way and measure the distance? Or am I mising something.

 

[rohare]

Can you scribe the side that doesn't come out at the base then open the lock all the way and measure the distance? Or am I mising something.

Nope, I do not have the combination. I have two locks of the same model. One that I have disassembled for reasearch and one that I do not have the combination to. From studying the one that I tore apart I believe I can, by taking measurements at about .0008 inches of accuracy, derive the combination of the lock. These measurements are taken by moving the dial to the position I want to measure, and then pulling on the shackle to determine how far it opens. If one of the internal wheels is in the correct position (and a few other details) then the shackle should open about .0008 to .001 inches more than if none of the internal wheels are in the correct position.

These are high security padlocks that, back in the 70's, were required on file cabinets containing top secret documents. They were disallowed for use because they were deemed insufficiently resistant to physical attacks (i.e. breaking them apart) but to my knowledge, nobody has ever opened one non-destructively which is what I am hoping to do. I'm using a dial test indicator with .0001 accuracy, but if I don't have a sufficiently stable platform to clamp the lock into, then it will be shifting around and messing up the measurements.

I thought using a bench vise was worth a shot but I need to spread the lock and shackle, not clamp them. Any solution that involves a handheld tool or manual manipulation is going to introduce too much error into the measurements.

 

[rohare]

There are bar clamps made to spread things apart -- kind of like a pipe clamp -- that are used by furniture makers/restorers to spread joints on chairs and such. Lee Valley is one source that comes to mind but am sure there are others. They can be clamped down to your bench thus creating a vise-like fixture.

-frank

This sounds promising! I tried a regular hand-held bar clamp but that introduced way too much variation into measurement. If there was one that clamped to a bench and was very stable it might just be the solution. I tried looking around the Lee Valley site, but didn't see one that could be mounted to a surface...

 

[chevydyl]

The idea I threw in would be used opening the vise jaws, simulating pulling the clasp away from the body. May I ask why you are doing this? Are you trying to get the lock open? I'm a little intrigued...

 

[rohare]

The idea I threw in would be used opening the vise jaws, simulating pulling the clasp away from the body. May I ask why you are doing this? Are you trying to get the lock open? I'm a little intrigued...

Yep, you've got the right idea. I may have to try making my own, as long as I'm convinced it won't break or damage the bench vise. I was just hoping that vise jaws like this existed and could just be purchased. As for why... just a hobby. I've done competative lock picking before and have cracked a few safes just out of interest and once as a demonstration. These locks (Sargent and Greenleaf 8088) operate in a manner very similar to your common combination lock safe (the good ones, not the ones you buy at office depot), but miniaturized and manufactured to an insane degree of accuracy (hence the careful measurements). To my knowledge, nobody has ever opened one without the combination or by breaking the lock. If anyone had, I'm pretty sure they would have bragged about it. I certainly will if I'm successful.)

 

[kd4gij]

Do you have a mill?

 

[rohare]

Do you have a mill?

Unfortunately no. I have a fairly decent array of hand tools and some good woodworking equipment, but not much in the of machine shop tools.

 

[kd4gij]

This guy has just what you need. Might be a little on the large side though. http://www.hobby-machinist.com/showthread.php/28523-What-might-this-be

If you have a large wooden wood works clamp it would be easy to use for that.

 

[francist]

Rohare -- I get what you're trying to do now. I've got the guts of an old Yale safe lock in my kitchen that I like to fool with every now and then after the safe guys showed me how all the wheels worked. Very interesting challenge.

The spreader clamps I see on the Lee Valley site might be a bit large and imprecise anyway, I'm wondering about something along the lines of a jewellers pin vise? I'll dig mine out and maybe post a pic if it looks promising.

-frank