Magnetic Random Number Generator for Your Fridge!! (Die)




Yep thats right throw it at the fridge and you receive random-ish numbers, Roll a Six and get to eat the Cake!

This instructable is my contribution to the fridge magnet group.

Essentially this project is just a few rare earth magnets stuck to a cube of wood

Step 1: Materials and Tools

21 Neodymium Magnets (5*5*3mm) (Disc magnets would have been better seeing you could inlay the magnets into the wood)
1 3.5cm cube of Wood
1 Tube of epoxy glue/resin
1 Varnish
Various grades of sandpaper
For this project you will need access to:

Some clamps
A Bandsaw
And a dust mask

You will also need periodically about 3 Hours as you can only glue about two magnets on the cube at any one time(due to the fact that these magnets like to jump free from the glue and stick to each other.).

Step 2: Making the Cube

OK your now ready to go.

Making the cube:

1. Get a block of wood.
2. Cut it into a rough cube using a band saw
3. Clamp a piece of wood parallel with the Band saw blade at a distance of just less than the smallest face on your cube.
4. Using this straight edge cut all the sides off your cube until you have a better cube..

Step 3: Sanding

Well this ones not a very complicated step, However it is slightly labor intensive unless you see fit to use the belt sander.

Just sand the corners and faces smooth using ever increasing grades of sandpaper.

Seeing i was only using soft wood Grades 80 and 600 were all i used.

Step 4: Glueing Your Fingers Together.

Ok we are now up the hardest most time consuming step Gluing.
You'll pretty much get glue EVERYWHERE unless well your a good glue'er
But don't worry your going to coat this in varnish so youl hardly notice

If you were to inlay Disc magnets at this step this project would be greatly improved. However, i have none of these "disc magnets" I speak of.

What makes this hard is the magnets tenancy to stick together or pull apart.
Hence you will need quick drying Epoxy / super glue.
Here i used 5 minute Epoxy.
You will need to hold (or clamp) each magnet in place until the initial drying time is up.

Oh and remember on a Die opposite faces add up to seven.

Step 5: Varnishing.

Once your sure all the glue on your RANDOM NUMBER GENERATOR is dry

Your ready to start varnishing.

Just paint on the polyurethane and wait for the RANDOM NUMBER GENERATOR to dry once again.

you'll probably need to have some turpentine to clean up any mess and also clean the excess of your brush if you don't the brush will become unusable.

Step 6: YOU'RE DONE !!

Well there you have it your very own RANDOM NUMBER GENERATOR.

surprisingly This die gives almost random results even with some sides having 6 times more magnets than others.

And it will stick when thrown from anywhere in the room.

And like always i would value any input on how to improve this Instructable , And would be interested in seeing anyone else's version of this project.

OH and VOTE for me so i can win a PRIZE : )



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    42 Discussions


    11 years ago on Introduction

    Save the fridge and improve randomness at the same time. --> use a foam block and put only one magnet on a side, using visual markers for the numbers. No weight distribution problem then. If you found a foam block you could "open" (like the puzzle shapes sometimes used as giveaways) you could put the magnets on the INSIDE.

    7 replies

    Reply 10 years ago on Introduction

    also it would make it more random because 6 magnets on one side and 1 on another... which one would get the hit. not very random :( but if you use 1 on each side inside the foam it wouldn't damage the magnets or fridge and would be completely random! we are all so smart :D


    9 years ago on Introduction

     yea im not throwing a wood cube at my fridge...
    ill use foam
    6 is the likeliest thing to (roll) cause it has the most pulling strength
    good idea tho

    2 replies

    Reply 9 years ago on Introduction

    wouldnt that be 1?
    6 has the most strength, so will attach to the fridge, then 1 will show...

    anyway, i dont like the idea of throwing stuff at my fridge either :D


    10 years ago on Introduction

    Ok, the question about the magnets loosing the magnetization is a simple answer. Magnets loose magnetization when you bang/tap them to another ferrous object. Reason for this is that your transitioning the +/- ions between the two, and actually you are not loosing the magnetization your simply lowering its magnetized value, example: you have a 5lb pulling force with one magnet and you tap it to another ferrous object (steel for instance) the 5lb pulling force now drops to 4.5lbs force while the ferrous object now gets .5 lbs while spreading it out. However if you do this enough you will arrange the ions completely and the charge is lowered to nil. Interesting concept though, if you heat up a magnet beyond the standard Curie temperature, 310F (590 C), you will lose it completely to never be remagnetized ever again. You should however take a paper clip and press it to the spot/spots of where the die was thrown to see if your refridgerator has become magnetized. Another fun fact, take a regular steel nail, point the tip not the head "Magnetic North" not "True North". Put it on concrete, take a hammer gently tap it from the head to the point, do this several times, once you have done it a few times or 10 or more to acheive maximum results place a string around it and try to balance the nail perfectly, now gently release the nail and watch it always point to "Magnetic North" as if it were a compass.

    1 reply

    Reply 9 years ago on Introduction

    hmm, 310F and 590C? no way :D
    my 30watt solder station already removes the magnetic force, and theres no way that reaches 590C, its probably more closer to 390C than that 590 :P

    System Folder

    10 years ago on Introduction

    I used two foam cubes that were used to ship a sleeper-sofa. I just drew on the numbers and I had (nearly) instant big foam dice. They were great to teach my 4-year-old addition. I would just drop them on the floor. They would bounce around and land on numbers and he would add them together. He started out by counting the pips, but he got better and after a while he didn't have to count anymore.


    11 years ago on Introduction

    this is a great idea, but needs some work: you should inlay the magnets by drilling a groove a tiny bit deeper than your magnet is tall and setting the magnet in there with some epoxy or whatever durable glue you decide to use - rare earth magnets can easily break and apparently so can some epoxy. you should also remove the differences in amount of magnets on each side by putting the same amount of magnets into each side and painting/drawing the numbers on.


    11 years ago on Introduction

    Great idea, and execution. I'm interested as to how close this gets to random. But I think you'd have to throw this at least 100 times to get some meaningful statistics... The alternative would be to embed magnets (evenly) in the wood, and paint your numbers on I suppose? L

    3 replies

    Reply 11 years ago on Introduction

    Ok here are the results of a 100 throw sample. 23% chance to throw a 1 18% chance to throw a 2 16% chance to throw a 3 19% chance to throw a 4 12% chance to throw a 5 12% chance to throw a 6 So overall not a even distribution however Id call that random enough(i would i expected less consistent results). (With about ten throws to go a magnet broke off the Five face) - could anyone recommend a superior glue? Yeah the alternative would improve this project greatly.


    Reply 11 years ago on Introduction

    Any quick set 2 part epoxy like the one your using is utterly worthless for stress situations. Its brittle and chips and cracks. Not to mention it turns yellow. But it sets quick and is soooo easy to use. try a marine epoxy, maybe a 2 parter in cans?


    Reply 11 years ago on Introduction

    More magnets on a side will lead to a stronger likelyhood of it sticking. If we can assume, as Lemonie said, that you've used the standard numbering system for dice, then your statistics generally fit the norm. Larger numbers being more likely to stick leads to smaller numbers showing more. You could try using only one magnet per side and the rest of the dots being uncharged metal bits with similar colour/texture. Or Lemonie's suggestion. If you really wanted it to be a bit more accurate (ie, random). But it seems great for what it is. Very creative. And a rather nice look, if I may say so, in its simplicity.