Combination Lock USB Memory Stick





Introduction: Combination Lock USB Memory Stick

The Problem:
I have a USB memory stick with built in security software, GREAT! However it tends to be a little unreliable when it comes to using the memory stick on computers other than my own either taking ages to get logged into it or even not getting access to it at all.

The Solution:
So i decided that after receiving a free 3D print from the last competition i decided i would design a combination locked USB memory stick using Solidworks 3D!! Which should be here any day?

Using 4 wheels numbered 0 - 9 gives me 10,000 Combinations!!!!!!

Here are the results and i hope you enjoy the step by step guide

****now available to buy at shapeways link below****

Step 1: USB Memory

The first step was to draw up the USB memory i had purchased for the project, it was relatively small 1Gb but it was all i could find at the time and it is specifically sold without a case for the purpose of making a case/container yourself, alternatively if your needing a larger memory capacity jusy remove the business end from one you previously purchased.

I started off by measuring the usb with a set of calipers and making a sketch of the PCB on the top plane and extruding it to the appropriate depth.

Next on the right plane i sketched the metal part of the USB (male End) extruding it also.

With the USB completed in one part i could now use it to design my casing around!!

Step 2: USB Circuit Board (PCB) Casing.

After examining a few USB cables lying aroung i settled on a measurement for the amount i want the metal end protruding from the casing and using this measurement along with the overall length of the PCB and a couple of millimetres for the casing thickness i was able to sketch and extrude a suitable casing length.

The catches/location points for the combination wheels were refined in the assembly at a later point!!

Step 3: Recieving End of the Casing Combination Wheels

The Recieving casing was a little more difficult and thought provoking to sketch and extrude never the less a suitable result was achieved.

With this completed i could draw the edn cap for it which would keep the combination wheels on and in place.

The next part to draw was the combination wheel.

Step 4: The Finished Product!!!

And so the completed USB casing should look a little something like this !!!

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    37 Discussions

    i love this idea and I've started making my own in auto-desk inventor BUT it would be helpful if you had included the dimensions for the pieces and maybe a little bit more detail on how to make each individual piece because i'm having a bit of trouble with the combination rings...other than that this instructable is definitely in the top ten for me

    I only use a manual lathes too but they are too bog to machine out the parts for this, a modelling lathe and a milling machine would be proper job.... Have you any photos of it van.

    i made one out of aluminum in my machining class, had extra time and i used a standard usb 3.0 flash dive. to be clear i did not use a CNC, im just that good on a manual lathe and knee mill =P

    1 reply

    The main problem I see with this is that it's made of plastic. It doesn't take a lot to break plastic. Perhaps some sort of strong metal (Steel, Titanium, etc.) and/or spikes attached to the case that the flash drive rests on in order to smash the chip if it's broken into might be a useful addition.

    Also, the issue of cracking it with tension is important as well. Some way to lock the discs when tension is applied would do quite well.

    However, this is certainly a novel concept. If it were a bit more secure (and reasonably-priced), I know of people who would buy it.

    Nice. As others have mentioned the removable part could potentially be too 'deep' to sit well when inserted into a laptop, but in fact this part doesn't need to be a complete cylinder anyway.

    If you flattened the underside leaving just the top two thirds or so of the cylinder it would still lock into the combination part, but would no longer have this issue.

    1 reply

    Who need security software when you have this? :) Very nicely done.

    2 replies

    Not really. With 10k combinations, and assuming each try takes 10 seconds (fast fingers) you could have it open in less than 27 hours using brute force. It just keeps the honest people honest ;)

    But I agree, well done, but let's see it when it's printed. ;)

    also when its printed, the finished product will be plastic. so if they wanted it that badly they could just break it


    5 years ago

    Yeah just reduce the male part jim.

    I'd made onde nor in 3D printer ,but is a lot of piece of PVC tube, in another Intructables (I can't remenber).But It's work well


    5 years ago

    Nice idea Robbie... Yeah Jakob in waiting on the 3d printer to churn it out... hope its here soon.

    So did you actually make this or just draw it? :)

    A very creative way to make something like that secure. Also in that casing, it's more difficult to lose :)

    1 reply

    and for those that like the brute force tension method, you could add slight notches, or 'false gates' to keep them guessing

    I can actually see one big problem right away. How in the world are you actually going to put the ring on the shaft. If the combination ring are actually a complete different piece and the shaft have border on each end that are actually bigger thant the inner diameter of the ring, you will never be able to put them in place.

    Ussually in a combination lock, the border facing the other part is put in place with fastener (bold, solder, or the ring is actually a nut with a looking bar).

    1 reply

    What he's done to work around this problem is to have a smooth cylinder for the rings, then have a cap that holds them in place. If you look carefully at the first picture in Step 3 you can see it.