Instructables

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
 
Remove these adsRemove these ads by Signing Up

Step 1: Materials And Tools

Materials:
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
Tools:
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

7.jpg
14.jpg
8.jpg
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.
1-40 of 41Next »
sabbott6 years ago
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.
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
yeah... but if six gets the cake, then I'd like higher odds of getting the cake
But the cake is a lie!!
Lol. I <3 that meme. I love this 'ible too!
Win Guy
Cake - Y U NO BE REAL?!
No, seeing that the six would stick to fridge you would want to bid on the number 1.
they sell foam dice that would work very nicely for this
KnexFreek5 years ago
 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
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
oh !!!! wow your right!!! lol good catch!
:D
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.
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
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.
berky936 years ago
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.
lemonie7 years ago
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
steven07 (author)  lemonie7 years ago
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.
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?
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.
Ooh, I'm thinking that your fridge must be quite battered by now... I appreciate that you gathered the data, does seem to fit a weighting pattern. I guess the 1 is opposite the six, 2 is opposite 5, but it falls out of sequence at 4? L
steven07 (author)  lemonie7 years ago
Yes i suspect that the 4 was just randomly higher for no reason due to the not gigantic data sample.
mrmath7 years ago
Pet Peeve Time! Your --> Belonging to you You're --> You are, as in You're Done! Sorry, but it's a pet peeve, and I have to pounce on it. I think it's a great idea, and I love it. You've got my vote. I would only make one small change to it. Perhaps you could use disk magnets, and inlay them into the wood. :)
rockyt mrmath7 years ago
your right! You're pet peeve is shared.
mrmath rockyt7 years ago
Your two funny.
lol math..... I agree....I dont know why thats so irritating 2 me (us) lol
your right. it should be spelled right.
(yes, I did that on purpose)
steven07 (author)  mrmath7 years ago
Thanks ! Correction coming.
steven07 (author)  steven077 years ago
Yes i agree inlaying some disk magnets would improve this project
ll.13 steven077 years ago
You can fill in the holes after embedding the magnets with glue and sawdust, Carpentry tricks.
mrmath steven077 years ago
No, se I was joking. You mentioned it in almost every step. I was playing on that. I actually, truthfully, and seriously, like it with the magnets you've got there. I don't know why, but I do.
I thought magnet + impact = bad? Or is that just with ferrous magnets, I know the ones we used in physics would just go dead if you dropped them too many times.
steven07 (author)  DeusXMachina7 years ago
Yeah i have also heard that. however i am experiencing no problems with my die. it probably is the different composition of elements in a neodymium magnet or the way the magnet is binded to together. i do know that if you hit these magnets hard enough they shatter. so in other words i have no idea does anyone else know whether it is acceptable to throw neodymium magnets around?
probably not a good idea, but with the small amount of force it requires to stick it to the fridge, its gonig to take a couple hundred throws for even one to break.
zachninme7 years ago
To make it correctly weight it, why not drill 7 holes in the H pattern on all sides, and fit the magnets in flush. Then you could paint over the non-used ones or something?
Visitor7 years ago
Unfortunately the distribution of the magnets skews the results. You're more likely to end up with a small number, since sides that have more magnets are most attracted to the fridge door.
Visitor Visitor7 years ago
A better approach would be to embed one equally strong magnet to each face and just paint the faces. That way the pointy magnets wouldn't dent the fridge door so badly when you hurl the dice.
steven07 (author)  Visitor7 years ago
yeah then it would have a more professional look to. once again if you read on i have adresed the benefits of inlaying the magnets into the Die - However convenience led me to his solution. as this is all i had laying round. Actually i think i will remake this with some more appropriate magnets net time i get some free time. You gave me negative rating? :(
I would embed one magnet in each side....drill a hole partially in, put the magnets in, and smooth a thin layer of epoxy on... then just slap it on the belt sander and spray on a coat of paint and you wouldn't even know the magnets were there!!
steven07 (author)  Visitor7 years ago
Of course but like i said if you read on. "surprisingly This die gives ALMOST random results even with some sides having 6 times more magnets than others." However it was still fun to make and dosen't look too bad.
1-40 of 41Next »