Michael Huebler’s masterlock article on Toool.nl

There is a new highly detailed lock article (PDF) at Toool.nl. And the big surprise is that it is not written by Han Fey…

The person responsible is Michael Huebler, and the lock covered is a prototype (named Axis?) of a new Master padlock.

Michael did a fine job writing the article, and we are honored he wanted to publish it on Toool.nl.

Axis, a new master padlock


Hi, my name is Michael Huebler, I’m a lock collector from Germany, and recently I was very lucky to receive a sample of a very interesting new padlock that is not yet available on the market – a combination lock from Master Lock® with a unique new user interface and a very clever mechanism inside.

Inspired by other papers on lock designs, such as the Abloy series by Han Fey, I decided to share the details of this nice piece of mechanical engineering with you, and I hope you enjoy reading about them as much as I enjoyed disassembling and analyzing the actual lock.

I would be very happy to receive your comments, corrections, or just a short note whether you found this paper interesting or helpful. You can contact me through http://www.lockpicking101.com/ where my user name is ‘mh’. You can find the most recent version of this paper at http://toool.nl/. Thanks for your interest!

(* BW:or you can leave your comments on this weblog)

new master padlock

52 Responses to “Michael Huebler’s masterlock article on Toool.nl”

  1. Han Fey says:

    Hi Michael,

    Good article, detailed pictures with explaining text.

    Certainly worth to be mentioned on Barry’s blackbag.

    You put the bar high for everybody who intends to write articles 😉

    Keep up the good work,

    Han Fey

  2. Lockpicker says:

    This lock reminds me of the old days bicycle lock (early 80’s)where you did movements, right, left, up and down, on a knob, to create a “secret” pattern till the lock was open.

  3. yehonatan knoll says:

    Hi Michael,
    I’m the designer of the lock. I must say I’m impressed by your deep understanding of the mechanism! But, you forgot to answer an important question: How secure is the lock, combinatorialy speaking? That is, is it more secure than a standard lock with, say, 1000 combinations? I straggled with this question, which is obviously more involved than the naive configurations counting you (correctly) did.

    Anticipating your answer,

    Yehonatan Knoll

    PS: The over-wide gate is a mistake in the mold, that has already been corrected.

  4. mh says:

    Hi Yehonatan,

    Nice hearing from you, congratulations on the idea to this lock, and also on finding a powerful licensee!

    Your question is good, but difficult to answer, as your lock is hard to compare to other locks… What would be a good measurement standard?

    One standard could be the number of steps someone has to take to try all possible combinations – maybe we can compare this to a Sesamee style lock, where you change one dial, then pull the shackle to try the combination, then change the dial again etc., doing this max. 10,000 times for a 4 wheel lock.

    With your lock, the attacker would move the joystick in a certain direction, then try pulling the shackle, then move the joystick again etc.
    I’m quite sure one could find a tryout sequence that has not many more than 7,500 steps and will try all the possible states of the disks. (BTW, I think calculating the number of possible states is not too naive, but a necessary step in understanding this.)

    Granted, that tryout sequence is way more difficult to enter than moving the wheels on a Sesamee lock – although it could have many 5-times-in-a-row parts – I guess the attacker would need some electronic help that would also help recover in case he got one step wrong…

    Also, if most users only use limited length sequences, say max. 6 steps, this would amount to only 1,460 possible states, hence shorter tryout sequences.

    But they are still sufficiently long to deter most people from trying it…

    Or what type of measurement standard did you have in mind?

    In terms of manipulation, I think it’s pretty good, it’s hard to get consistent feedback from it. But let’s first see what happens once people with better skills get their hands on the mechanism.

    One more question – which document version did you read? I think I got the gate width part wrong in the preview versions, and I corrected it in version 1.0 which is posted here (see footnote 1 on page 4). Now with a different mold, I guess you still need Phi – 16 degrees or so, don’t you?


  5. Tom says:

    My thoughts on the math part:

    Michael calculated that the lock has 7501 different combinations. I would say that in general this lock is less secure than a standard combination lock with 7501 combinations. (But it can be more secure as well depending on the set combination). This is because there are multiple combinations that are equivalent. When you put all the combinations that are equivalent into a group you see that not all groups have the same size. Michael pointed out that considering sequences of max 11 operations there will even be a few groups containing only one sequence. This means there are probably also groups which are significantly larger than average. The issue is that the (presumably random) combination that a normal user (without knowledge of the internals) will choose is most likely in one of the biggest groups and therefore more easily guessed/brute-forced compared to a normal lock. On the other hand if the user (by relatively small chance or by knowing about the internals) choses a combination that is in a small group the combination will be harder to break compared to a normal combination lock.

    Consider only sequences of length 6. There are 4^6 = 4096 of them. Assume the completely imaginary and exaggerated division that half of them are equivalent and that the other half of combinations are unique. Then there would be 1 + 2048 = 2049 really different combinations so for a normal lock one would expect that the chance to guess the combination would be 1 out of 2049. Half of the users will chose a combination in the big group. 50% of any guessed combination will work. The other (lucky) half of users will have chosen a combination that has only a chance of 1 out of 4096 to be guessed. The chance that a random combination works on a random lock is avg(1/2, 1/4096) which is slightly more than 0.25 (1 out of 4). Not what you would at first expect from 2049 different combinations.

    What all this means for this particular lock and how it would relate to a 1000-combination lock I really don’t know. It all depends on how evenly the combinations are distributed across the equivalence groups. (And I don’t feel like calculating that I’ll probably only make mistakes and get headaches from it ;-P )

    Besides the (boring?) math, I really like the mechanical design. Very clever!


  6. Jim Kirkpatrick says:

    This lock is described in US patent 6,718,803. From the patent office’s main web site (http://www.uspto.gov) click on Patents, jump to Search Patents, and search for it by number (or search for Yehonatan in the inventor’s name). It also appears that US patent 6,298,694 is an earlier design with similar goals. Reading the patent description may reveal more about the mechanism.

    P.S. To view patents, you may need to download a browser plug-in. The images are in a TIFF format that Microsoft may not support. Alternatively you could try http://www.freepatentsonline.com which uses PDF but you need to “register” with them.

  7. Barry says:

    Jim: Google is your friend 😉

    Google now has patent search (www.google.com/patents), a service that does not require plugins. Not sure how complete it is, but for the few searches I tried it worked.

    The link to the patent is:


  8. mh says:

    > Reading the patent description may reveal more about the mechanism.

    Hi Jim,

    I was told about the patent soon after I published the paper (I wrote it during a vacation without internet access…), but it’s written like a good patent – it explains enough to make the claims – to get a good understanding of the mechanism, I would rather recommend my paper 🙂


  9. Andy58 says:

    this is a wery good article! I think, i have missed you at a lockpicking meeting in munich where this lock was shown. I have never seen this lock but now i understand the mechanism, the article is very clear to understand.

    Does anyone know when this lock will be available to buy? It is very interesting and something different to other locks.

    Best regards

  10. sonical says:

    We here assumed that lock will be being picked very intelligent lockpicker. And that is terribly wrong.

    Smart minds work on smart things, not school lockers. Unless it’s MIT.

    School lockers are opened by quite more brutal methods.

    That’s why lockers are made of steel, not plastic.

    Unfortunately, this lock inside is plastic, yet outside is brass, what makes it a something that is unsafe, yet trys to look safe.

    Trying out a cigarette lighter below lock to warm it up “slightly” will definitely make it jam or open (depending on temperature).

    We know well how much lighters are used in school everywhere. Trying out to fry and jam some twenty lockers during a brake, could be definitely fun for a student.

    Also sun light or fire in nearby trashbin might definitely make it jam.

    Math stuff on combinations with such “non-trivialy explainable systems” is even less secure than it seems by the most skeptic reviewer.

    Even if user has set a complex combination with 10 steps, there is a chance that a “bad guy” comes, presses one key (say [left]) and tries the ridge — and lock opens.

    It’s not the case for a lock with seemingly trivial code wheels. If user sets a code, and rolls it into any random position, then whatever the lockpicker does: chance that his lock opens is 1/9999 (the 10000-th combination is ruled out as it’s the initial “incorrect” position)

    Possible simple answers the problem with any overy complicated system, like rijndael for example. Or a authentification key system used in a DS2432 chip or similar ones.

    The fact that it’s hard and complex to describe system behaviour with it’s numerous feedbacks, doesn’t mean it’s complicated to open.


    P.S. First sign that an algorhythm or concept is actualy weak: it is approved by government or police. That’s because everything available to general public should be “unlockable” without excessive effort.

  11. mh says:

    If you would like to see the mechanism in motion, check out http://toool.nl/Image:AxisVisualizer_V1.0_p.swf 🙂


  12. mh says:

    Here’s a podcast that features the lock and an interview with Yeshai Knoll:
    http://lsieducation.com/blog/2009/01/psn007-master-lock-axis-a-unique-padlock/ (the links are listed on this page)
    http://lsieducation.com/blog/2009/01/psn007e-master-lock-axis-a-unique-padlock/ (an enhanced version that includes pictures)


  13. mh says:

    Well, this revolutionary new lock is now finally officially announced and should be available very soon:


    The name in the U.S. is Master Lock 1500iD Speed Dial(TM), the European name might be different;
    anyway, it seems like i’ll be able to bring some units for you to HAR https://har2009.org/
    and if all works out as planned, you’ll also be able to look at some cutaway versions, and learn how to manipulate them – they really are a nice challenge 🙂

    See you at HAR

  14. yehonatan knoll says:

    Here are some additional features of this lock:
    1. If you want to know whether your lock was attacked, just enter the first few movements of your code after locking and resetting it. Upon completion of the code, your lock would open only if no one played with its knob or shackle (this would work also with a standard single dial lock).
    2. If a number of people want to access a safe (for example) only when all grant their permission, do as follows. When programming a new code, each person consecutively enters a secrete subsequence of the full code. This is equivalent to locking in parallel with several locks, and no `coalition’ among the group can assist them in unlocking the lock (unlike, say, in a multiple dial lock with each digit entered by a different person)

  15. yehonatan knoll, nice ideas, but the last one is circumvented easily, as the lock has limited number of unique combinations and it can be decoded (I don’t know the technique).

  16. mh says:

    Jaakko, the current (padlock) implementation is obviously not suitable for a safe, but it could be extended to more states, and also be made more resistant to manipulation, and then this has a real beauty to it – any number of people can each use any number of movements in their personal sequence… As long as they do not push the reset button to cheat the others before them, it’s kind of a nice and unique concept.
    Also, it’s not symmetrical – if someone wanted to open it without the others, the last person entering the code would need to try out less sequences than the others.

    BTW, I consider the decoding attack (cf. https://wiki.har2009.org/page/Workshop:Padlock_Hacking ) on the padlock as a nice puzzle and challenge, but not really as a weakness of the lock, because it fails quicker and more easily to simpler attacks like a drill, a bolt cutter, or a hammer. IMO it’s not the type of padlock you would put on a cargo container, but entirely suitable for a gym locker.


  17. Jennifer says:

    very interesting article…. but just one thing. I bought the lock myself and i was really happy with it. but then i reseted the combination to my own combination. then a terrible thing happened. i did not touch the lock for a couple of days and now i forgot the combination. i can’t open the lock at all and i’m really upset now. Is there any way that i can open the lock??

  18. mh says:

    Jennifer – the lock can be decoded, but it takes a while and you need a precision tool for that. See https://wiki.har2009.org/page/Workshop:Padlock_Hacking for details.
    Or try to remove the screws in the back, but the middle screw is quite hard in most of the locks I’ve seen, so you will likely just damage your drill bit.
    The simplest and most economical solution will be to buy a new lock… And then write the new combination down, or use something like https://www.combolocker.com/

    One more thing: If you think you remember the combination, but it just doesn’t open with that combination any more, try out different ways to input that combination: Let the knob snap back after each move, and / or try to hold it secure so that it cannot snap back. This sometimes makes a difference on some of the locks.


  19. daniel says:

    hi i’m in highschool and i brought this lock for my locker and i made the combonation and did it again and it wouldn’t open and i cant reset it and my dad tried unscwering it but the screw is different so can u plz tell my how you unscrewd the lock plese and thank you


  20. mh says:

    If you can’t open it after re-programming, I would rather recommend to try this:
    1) just push in the shackle and pull it up, you might have accidentally pushed in the shackle (reset the lock) during reprogramming.
    2) push the shackle in, then dial the old and then the new combination; you might have forgotten to reset the lock during reprogramming
    3) push the shackle in, then dial the new combination, but let the knob snap back instead of guiding it back. Or, if you usually let it snap back, guide it back this time. Letting the knob snap back might give a different result than guiding it back: Letting it snap back might effectively move the knob halfway into the other direction as well.

    Good luck,

    To open the lock housing, use a diamond coated thin Dremel attachment to grind 2 holes into the middle screw, then heat the lock up with a hot air gun, then unscrew all 3 screws. For the middle screws you now still need a special screw driver, the 2 others unscrew with a Philips screw driver while hot.

  21. Let’s assume that the combination has at least two different knob movements. We work backward from the last knob movement, the one which opens the lock.

    Recall that each knob movement moves three disks and leaves a fourth disk unmoved. To simplify things, let’s start by assuming that the next to last and the last knob movement are different. After covering that case, we address the case where the last knob movement is a repetion of the same direction.

    The last knob movement will always move the gates for three disks into alignment with their fences. The gate for the disk that didn’t move must already be lined up with its fence, or else the lock would not open after the last movement.

    The next to last knob movement moved the one disk’s gate into alignment with its fence and two other disks into positions where the last knob movement would align them with their fences.

    For the repetition case, the three disks moved by the last knob movement are in position to move as a group into alignment after two or more knob movements in the last direction.

    In Michael Huebler’s “Inside View” document, he states under “Manipulation techniques” that there are two ways to determine if one or more disks are aligned with their gates. From the above, there are two knob movements which will never leave a gate aligned with a disk. So, we try each of the four directions five times in a row, testing after each time to determine if a gate is aligned.

    We should find two knob movements which never align a gate, one knob movement which aligns a gate exactly once every five times, and one knob movement which aligns gates 1, 2 or 3 times. If we find two knob movements that align gates once every five times, one of them is aligning three gates at once. We make two knob movements in a direction which never aligns a gate, to misalign two of the gates and force one direction to align gates more than once.

    Now, we can determine the angle, relative to reset, for the gate on one disk. The other 3 disks will be a little trickier, since we know when one or more disks are aligned, but not which ones. However, we can use a sequence of movements to sort that out. Once we have the four angles, a table can be used to find the sequence of 2 to 11 knob movements which will align the gates with the fences.

  22. mh says:

    “Master Unlocked”, this makes sense (although I didn’t try it).
    You can find the method I used successfully here: https://wiki.har2009.org/page/Workshop:Padlock_Hacking / esp. in the document that’s linked there: http://toool.nl/Image:MhPadlockDecoder_Manual_V1.0.pdf


  23. This is an outline of a process, which needs refining into a “cookbook” procedure, which will, if my analysis is correct, allow users to nondestructively open locks with misplaced combinations. The process requires the ability to determine when one or more disks are in correct position. The process requires trying 125 combinations in groups of 5, where, for each group, a single knob movement is made 5 times in a row and the lock tested, to see if it will open, each time after the knob is moved.

    Once the last knob direction and penultimate (next to last) knob directions (from my last post) are determined, the lock can be reset and then, using a series of knob movements, the disk for the penultimate knob direction is moved into correct gate position. After that, the knob is moved once in the last direction and the lock is tested to see if it opens. If not, the last knob movement is repeated and the lock tested again, up to 4 more times.

    Note that there are 5 x 5 x 5 = 125 disk positions to test and we have tested 5 of them. The other 120 combinations are also tested in groups of 5. Reset the lock and repeat the same knob movements so the lock is in the same state as before. Then, make one of 24 combinations of knob movements that rearranges only the disks moved by the last knob movement and does not repeat a disk position already checked. (The fourth disk will get moved but it will end up in the same place where it started.) Each of these combinations begins and ends with a move in the last direction. Check for the lock to open. If not, the last knob movement is repeated and the lock tested again, up to 4 more times.

    The process can be simplified so it is not necessary to reset the lock 24 times. There should be “Rubik’s Cube” like maneuvers between tests of groups of 5 to cover all 125 disk rearrangements.

    I haven’t tried to work out the maneuvers. However, Michael Huebler’s document and visualizer convince me that they exist and can be worked out.

  24. James Koppel says:

    To protect against AUDIO spying: Make every interval between moves of equal duration and/or have another lock in your hands to make DUMMY SOUNDs……

  25. Mark Wheelhouse says:

    I just bought this lock a few minutes ago, tried the initial combination and it worked. Tried it a dozen or more times because of the novel nature of how it works and it worked each time. I handed it to my 6 year old son and showed him how to open it. He did so only occasionally and then could not open it any more. I now can not open it either. Any idea why it won’t open any more. The plastic cover on the back covering the reset mechinism is still in place and undesturbed.

  26. mh says:

    Mark: It might be something as simple as -letting the knob snap back after moving it-.
    The knob should not snap back, because then it could move too far into the opposite direction. Instead, try to guide it back to the center.

    Also, do make sure you really reset the lock before entering the sequence, by pushing the shackle into the lock body a number of times.

    If this all fails, return it, or better still, send it to me for further analysis 🙂


  27. Michael He says:

    Hi, everyone, I’m just a user of this lock, it’s so different from others, I like it very much.

    But I had a problem, after I reset the lock properly, I can’t open it anymore, (of course I remenber the combination). I would like to know if there is any way to open it, or reset it again.

    Thanks guys.

  28. mh says:

    Michael He,
    have a look at this comment: http://blackbag.toool.nl/?p=183&cpage=1#comment-180926
    Did that help you?

  29. John says:


    You are a lock saver (and saved me $8)!

    My daughter just bought one of these locks for her locker for school which starts in a few weeks. She was showing me the lock and saying how cool it was. She asked me to help her use it. We took the instructions and unlocked it with it’s initial combo and then we set a new simple combo. I was telling her how she may want a slightly harder one. She proceeded to set a new one while I was not paying attention to her. When she was finished she closed the shackle. She tried now to open it and could not get it to open…ugh! We tried and tried, thinking that she had not fully moved the slider to one of the positions or something. She was bummed to have to buy another one and we were trying all combo’s we could. Finally, I started googling. I came across this thread and your suggestion:

    2) push the shackle in, then dial the old and then the new combination; you might have forgotten to reset the lock during reprogramming

    I tried using the first combo and then the second in succession and “plink” the shackle opened!! My daughter gave me a big hug and we were glad to not have to pitch this one and buy a new one. Thanks for the suggestion.

    : John

  30. James Koppel says:

    Hello, again. Well here’s what I’VE been doing– Create e new combination of 8-11 moves. Reset the lock. Scramble the lock with MANY random moves, quickly and without memorizing what you are doing. NEVER move the lock to “re-set”. Pull on the shackle with your index finger. The middle section of your middle finger will be pushing against the lock body adjacent to the fixed side of the shackle. Your thumprint area will be firmly on the juncture of the opening side of the shackle and the lock body. Using your knowledge of stuck moves and small shackle move ments. the lock will open in 2-20 minutes

  31. James Koppel jamenkop says:

    Continuing from just above– By rapidly and randomly scrambling the lock with many moves and NEVER re-setting the lock, you are basically dealing with an unknown combination except that you know the last move. However,
    the KNOWN last move isn’t necesarily the ONLY last move. Knowing how many moves you originally programmed into the lock is not relevant at all, as it has been totally scrambled and you will NEVER re-set it to START.
    This is a great way to prepare for having the confidence to deal with totally un-known combination that starts from the “reset” position as per normal.
    On more than one occasion I have been suprised to open the lock while “taking it easy” : listening to a radio talk-show, etc. In other words, once you have the tecnique down pat, a bit of subconcious casualness CAN enhance the procedure.
    p.s.– My brand new dial indicator is still in its box and it will probably be anything more that an intriguing piece of mechanical art– much like one of my Speed Dials.

  32. Cyberholmes says:

    Just created a database of every possible state of the lock, the shortest length combination to reach each state, and the number of combinations that reach each state, and according to my info, there are no states that are reached by only one combination (excluding the reset-only state). For example, the example of such a state in the paper was ‘U, R, R, L, L, D, U’, but this state can also be reached by the combination ‘U, R, R, L, U, L, D, U’.

  33. mh says:

    You are right, the statistics table in my paper is not correct – good find! For this state, in a space limited to 11 movements, there are the two sequences you mentioned.
    I hope you enjoyed analyzing this lock as much as I did 🙂


  34. Cleveland Robinson says:

    I have invented an accessory to the padlock or combination lock but because I have no funds available, I am left to shop my invention around to diffenent Co. Please contact me at rcleveland78@yahoo.com if you are interested making your product even more secured.

  35. James Koppel jamenkop says:

    Concerning my 2 posts above from July 29/th 2010– On several occassions the lock has opened on a HALF-MOVE.
    That is, the lock opens on a direction other than the programmed combination and the 4-direction knob is STUCK
    halfway into full direction. It cannot be released until the lock is fully closed and reset to the ‘start’ position.
    Examining Michael’s diagrams of the four basic mechanics of wheel progression we can immediately see why this is
    the case in certain instances. I would be interested in PROGRAMMING a combination with one or more half-moves,
    but I have not gotten around to it. Would anybody like to try this and report back on it to this page?

  36. MZ says:

    @Jameskop: My son just reset his combo, like he’s done a few times already, but now can’t open the lock. We’ve tried the old combo + new one, in case he forgot to reset, with no luck. I’m thinking we should now try your method to try and open it. HOwever, when we pull on the shackle, the way you mentioned, the knob seems to get stuck as we move it around, and we’re not sure if we are pulling too hard on the shackle. Any tips on how best to put pressure on the shackle and move the knob? thanks!

  37. James Koppel jamenko[ says:

    MZ: The stuck knob is only a general sign of what to do next. You do NOT keep pulling on the shackle when this occurs. You let it go and move on with the bit of knowledge that you have acquired. You must click on the red PDF link at the top of this page to fully understand this. Plus
    a certain amount of intuition and experience are required.

  38. James Koppel jamenkop says:

    Let me try to explain. First go to the red PDF link at the top of this page. Try to master your understanding of it completely. Second: When the button gets stuck in a position– this is a VAGUE sign of what to do next. The idea is NOT to keep on pulling the shackle but to let go and the button will spring back to the center. Using your knowledge from the PDF paper plus experience plus intuition, you should be gaining a sense of what to do next.

    If the button remains stuck after you have released the shackle gently flick it with your finger or hit the back of the lock lightly against a table edge.

    Third, when I say that the lock will sometimes open on a HALF-move and remain there until the lock is closed–
    That does NOT mean that there was any difficulty at all in pushing outwardly that half-move. It will have been very smooth and normal.

  39. Tony says:

    euh.. i just bought the new 1500id and lost the paper instruction and i wanna know if all locks have the same code for the first code and if it is whats the code plzz???

  40. mh says:

    no they have many different initial codes

  41. Mark says:

    I was given one of these locks and promptly tried to set my custom combination incorrectly.

    The initial code that was working was U R D L. This unlocked the lock. I moved the reset lever to the up position and closed the lock. I pushed the shackle down twice to reset the tumblers. Then without opening the lock I dialed in my new code. It was UU RR DD LL. I then moved the reset lever down (again without opening the shackle).

    Now neither the old combination nor the new combination works.

    Is the lock in some strange state that no code will unlock it or can I go through the methods listed in this discussion to figure out what (seemingly random) code will now unlock this?

  42. forgetful shmuck says:

    Sweet, just got it open! Earlier, I forgot to reset mine before reprogramming. Initial code + new code didn’t seem to work. Guiding the slider back vs. snapping it back also didn’t work.
    But then I tried pulling the shackle (while entering initial code + new code), and that did the trick!

    P.S. I’ve heard that repeated moves in the same direction (e.g. left left) can cause problems. Maybe that was my problem… I’m not using the Konami code again -__-;

  43. forgetful shmuck says:

    Success! I just got it open! Earlier, I forgot to reset mine before reprogramming. Initial code + new code didn’t seem to work. Guiding the slider back vs. snapping it back also didn’t work.
    But then I tried pulling the shackle (while entering initial code + new code), and that did the trick!

    P.S. I’ve heard that repeated moves in the same direction (e.g. left left) can cause problems. Maybe that was my problem… I’m not using the Konami code again -__-;

  44. CaitSith2 says:

    Reading some of the previous comments, plus playing around with the visualizer, gave me an idea, as to how to make a combination, that can’t be found with full up/down/left/right entry. At the end, push the dial only half way. This creates an angle on the disks, that cannot be recreated with any combination of full steps.

    Anybody attempting to bruteforce using only full steps will never align the gates that way, if a half-step was used.

    Another thing with half-steps, is that the lock will open, if there is only one half-step, and you are pulling on the shackle while entering that half-step. If two half-steps in different directions are entered, then it won’t unlock on that pull, unless you are on the final half-step.

  45. jamenkop (post#5) says:

    I did the half-step combo-set with varying amounts of a 4-digit factory set. (L-R-L-U). Last digit alone went great. L+R was also no problem. All 4 as half-moves WORKED– BUT it was very tricky to get it just right to open. It required much precise limited motion of varying distances and, even then, took up to 3 or 4 miniutes to open. by the way, it seems to me, from a non-analytical intuitive perspective, that any combination with any number of half-moves has a CORRESPONDING COMBINATION WITH ALL REGULAR MOVES. James Koppel, Brooklyn NY USA.

  46. mh says:

    Hi James,
    I don’t think that’s the case:
    Try . This gives [0;-1] on the left and right disk and [0;0] on the top and bottom disk. That state cannot be reached with regular moves.

  47. mh says:

    … Try (reset, half-up) …

    Don’t use angle brackets here…

  48. James Koppel says:

    Thanks ,Michael, for the analysis!
    Looking at the various starting points for the pins in the PDF, we see that all part-moves involve only the outer surface of the long outer barrier. One outer barrier is shown to give an option possibility of (0 to -26 degrees) of motion in one partial move, depending upon what percentage of a half-press you choose to do.
    Another starting point shows an unimpeded space giving ONLY (0 degrees). Another sketch (row 3, sketch A) shows an option of (0 degrees to “less than” -26deg.)
    So there is a lot to play aaround with here…. jamenkop

  49. Duggie says:

    I did the same thing as so many others here. Reset the combo, now it won’t open. I know I have the correct combo as I wrote it down before resetting it. This is my 2nd lock where this happened to me. I figured it was a fluke the first time, but it happened again! So frustrated with this thing! Tried all the suggestions above to no avail. Damn.

  50. Nigel Tolley says:

    Any chance of re-uploading the PDF? I was sure I’d got a copy somewhere, but can I find it again?

  51. Walter says:

    It’s at the Toool site under Publications, see https://toool.nl/Publications