Master Combination Padlock: Cracking Thereof

A Master Combination Lock emerged in locked condition from a box o’ stuff I handled during Mad Phil’s Great Cleanout. It’s not the highest security lock you’ll ever meet; about 15 minutes of fiddling produces the desired result:

Master Combo Padlock - opened

Master Combo Padlock – opened

A bit of searching suggests it’s similar to the Master No. 1523D Combination Padlock, although this one came in pink. The doc describes how to change the combination:

  • Unlock (or crack) the lock
  • Pull off the spring-loaded endcap (I had to pry with a screwdriver)
  • Slide off the combination wheels
  • Reinstall in desired orientation

After removing the cap and wheels, it looks like this:

Master Combo Padlock - wheels off

Master Combo Padlock – wheels off

Each wheel fits onto a rotating metal disk and engages three teeth, one of which has a notch. Align all four notches with the Master logo / index line and the lock opens:

Master Combo Padlock - dial alignment marks

Master Combo Padlock – dial alignment marks

Given just that picture, I think you can figure out how to get past one of these in a hurry. Right?

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  1. #1 by Red County Pete on 2012-12-29 - 19:35

    Used to have the chain version of this, with a piece that slid in the barrel. If you were patient, you could rotate each ring until you felt a bit of a detent. That was most likely the number for that one. Repeat until open. Now, assuming the pink hoops are a not-too-tough plastic, I suppose you could remove one with diagonal cutters, thus leaving a gap. You could leave some rings on, sliding them out of the way.

    Memory from the college newspaper. Letter to the editor thanking the bike thief who merely stole the lock and chain, leaving the bike. This was in the early ’70s, when my 1-speed Schwinn was par for the course on campus.

    • #2 by Ed on 2012-12-29 - 20:10

      rotate each ring until you felt a bit of a detent

      That’s about what I did here: figure out how to pull the shackle while rotating the rings, then get the correct ring sequence. When it was all said and done, the combination should have been obvious (and is not shown in the picture).

      Back in the day, I could’a done better… even if I was just the dorm’s third-chair lockpick. [grin]

      • #3 by Red County Pete on 2012-12-30 - 11:39

        Sounds familiar. (What is the fascination mechanical things have for EEs–is it the fact that you can actually see what you are doing without instruments?) My EE roommate and I were pretty good at the small locks, such as found on desk drawer locks. I can barely do it even now. Never tried house-key type locks, though.

        The old Master padlocks with a dual-sided key used to be susceptible to a master-key hack. Take all the teeth off but the top (so you had a tee) and you could open any such lock in seconds,

        • #4 by Ed on 2012-12-30 - 12:09

          you can actually see what you are doing

          Some of that, for sure. These days, most engineering amounts to rearranging the state of magnetic domains all day long; it’s nice to have a gadget to show for your efforts… and to show off!