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Making an electromagnet sign

  1. Dec 4, 2015 #1
    I am making a sign out at my farm. I am making everything myself and have come up with an idea on getting the letters to stick to the front of the sign with magnets. I just have plastic letters with magnets glued to the back and they just stick on the front of the sign that has a galvanized metal sheet. (18 gauge). So they stick on the front of the sign no problem. Now what I am trying to do is get the letters to stick to the front of the sign with an electromagnet so the letters stick on and can not be stolen or re-arranged. The sign itself is oval and about 6 by 8 feet.

    So I need to some how make the face of the sign a large electromagnet. I am hoping to make one that will have a lifting force of say 50-100 lbs. Now with the face only being 18 gauge it is very thin and kinda impossible to wrap copper wire around it. So here is what I am thinking might work and will diffidently need some input before I start investing money into it.

    Here goes....what if I bend a 1 inch lip all around the face of the sign it self. So the sign will now have a face with a top,bottom and 2 sides all around it at 1 inch. Then I would use that lip and start to run copper around and around the sign. Hook both ends up to my power supply and I have a large electromagnet sign!!!!! I hope!!

    So if anyone is an expert in this field please I would love to hear from you. Let me know if I am on the right track or if I am out to lunch!
     
  2. jcsd
  3. Dec 4, 2015 #2

    DaveC426913

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    I'm afraid that your design will result in the following:
    1] you will have a truly monstrous electrical bill
    2] it will shortly be covered in all sorts of ferrous flotsam and jetsam, including - once your tormentors discover it - some new and truly creative ways to deface your sign
    3] your letters will still be stolen/rearranged.

    There is nothing you can do that will stop a determined vandal. Might as well spend little and simply discourage them.

    Put a sheet of plexi over the front of the sign, with a frame that has a lock.
     
  4. Dec 4, 2015 #3

    davenn

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    its easier to get more powerful permanent magnets than electromagnets
    and as Dave said ... its gonna give you an additional power bill
    There's no point or advantage going to electromagnets


    Dave
     
  5. Dec 4, 2015 #4

    DaveC426913

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    That's an understatement. It's going to have an enormous draw. And it must run 24/7/365, with zero downtime. One brownout and he'll just have a puddle of letters at the base of his sign.

    Not to mention the danger from fire or electrocution.
     
  6. Dec 4, 2015 #5

    davenn

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    no it wont work like that

    as said, use permanent magnets google rare earth magnets
     
  7. Dec 4, 2015 #6
    Hey Daves, Thanks for the input. Not to worried about people stealing the letters as much as kids coming around and re arranging them. Its out in the country so major vandalism isn't really a problem. I know I could just easily use a vandal guard on it but I kind of like to play and build stuff. I'm a farmer we build everything. LOL.

    So I guess my question is would my set up work or not? Sounds like it would but the cost to run it would be high so maybe need to find a work around. Dave you said something about using permanent magnets but how would that work? I need to somehow turn the magnets on and off in order to change the letters.

    Can you guys think of any other way to create a magnetic field on the front of the sign. What if I used a smaller electromagnet and connected it to the front of the sign face and once turned on would it not magnify the sign face??
     
  8. Dec 4, 2015 #7

    DaveC426913

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    To make an electromagnet, you would need to give the sign some thickness, like a foot or three. Then coil the wires around the thickness. The part that is magnetic is the core's ends.

    See here:
    xl_electromagnet.gif
    It is the head and tip of the nail that are magnetized. Your letters would have to be stuck on the flat of the head.
     
  9. Dec 4, 2015 #8

    DaveC426913

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    You could use high-strength neodymium magnets. Make your sign out of half inch thick steel, then use neodymium magnets to stick em on. They'll stay stuck real good. You can then fashion a wedge to work under them to lift them off.

    Here they are at work.



    It may be expensive.
     
  10. Dec 4, 2015 #9
    Hey Dave, That was kinda my idea with the 1 inch lip all around the sign face so I have something for the wire to coil around the sign.
     
  11. Dec 4, 2015 #10
    The plastic letters now have strong neo magnets on the back of them so they already stick to the sign no problem. But I guess what I am trying to do is lock the letters on the face with a strong magnetic field.
     
  12. Dec 4, 2015 #11

    DaveC426913

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    That won't work. The magnetic field is perpendicular to the plane of the coils.
     
  13. Dec 4, 2015 #12
    OK that was my main concern was if the lip would work or not but your saying no. I was 50 50 on that part!
     
  14. Dec 4, 2015 #13
    What If I hook up a say a 1200 LBS electromagnet to the face of the sign. Once I turn it on should the magnetic field transfer thru the face of the sign and thus making the face a big electromagnet. Now I know I would not have 1200 LBS force running thru the whole face of the sign as I am sure I would lose force thru-out the face but would I not have some or say at least 50 -100 lbs? Just another idea I came up with.
     
  15. Dec 5, 2015 #14

    DaveC426913

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    That would work, yes.

    Don't die.
     
  16. Dec 5, 2015 #15

    billy_joule

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  17. Dec 5, 2015 #16
    LOL thanks Dave I will try not!!! I may start with lets say a 500 LBS to start. 1200 may be a bit much. See I have been kicking this idea around for a while and that was my original ideal to connect an electromagnet to the face of the sign but I was told that would not work out. But I kinda always thought it would so now I have to try it out.

    And Billy that is exactly what I am trying to build, I have looked at the door lock ones for some time and thought that it would work. That is where I found the 1200 LBS magnet lock.
     
  18. Dec 5, 2015 #17

    berkeman

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    Well, I'm an engineer, not a farmer. We don't keep trying to design something that doesn't make sense. In this case, I would just put a locking piece of Plexiglas in front of the sign and call it done. :smile:
     
  19. Dec 5, 2015 #18
    Well you find something that makes sense to you as an engineer and I will keep doing what makes sense to me as a farmer. Want to thank everyone who helped me out with this and I will let you guys know next week how I made out. Thanks everyone!!!
     
  20. Dec 5, 2015 #19

    Averagesupernova

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    Not doing anything for the image of farmers. LOL. No one who has the responsibility of most modern day farmers will come up with a silly scheme like the one described above.
     
  21. Dec 5, 2015 #20

    meBigGuy

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    Buy an LED billboard.
    Huge electro Magnets are a bad idea, and will just attract different sorts of vandalism. Not to mention the ease of the vandals just disconnecting power and re-arranging the sign. (are your messages unpopular?)
     
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