Neodymium Frag Racks

Discussion in 'DIY' started by denzil, Oct 24, 2012.

  1. denzil

    denzil Webmaster

    Yeah, I've kind of done away with the idea of using those magnets due to the cost/demand of them. I pretty much settled to using zip ties and base mounts to hold up the racks. They're definitely not pretty but certainly functional.

    I'm working on getting the frag tank set up as soon as possible so I'll probably just leave this be until I decide to come back around to it.
     
  2. zeroinverse

    zeroinverse Guest

    I always attend the WCR meetings, so happy to bring back some frag-a-racks back to bay area for people interested.
     
  3. denzil

    denzil Webmaster

    Yeah, I'd prefer something that's already made, haha. How much do those run, Ron?
     
  4. neuro

    neuro Webmaster

    I've made the first part of the frag rack: the neo magnets covered in hardened resin.

    Even that took forever, and countless messes and things I wished someone told me before I did it.
    I didn't even get to the point of attaching the frag tray to them.

    I still have two sets of magnets I can use to glue frags onto, but I have yet to find something I want to put on my back wall.

    If I could do it again, I would buy a professional made rack as long as it didn't cost a fortune.
     
  5. aqua-nut

    aqua-nut Supporting Member

    Not quoting exact price here but IIRC, frag-a-rack is about $25. I have one. It's great and looks great too. If you have a tank with sides thicker than 1/2 inch, I recommend getting an extra magnet.
     
  6. neuro

    neuro Webmaster

    woo nice ok that's good to know!
     
  7. Vincerama2

    Vincerama2 Evil Overlord

    Check these magnets http://www.magnet4sale.com/Neodymium-Magnets-N42-OD0.75-XID0.1875-X0.375-Epoxy-Coated.html

    I bought those and also smaller ones.

    I used the smaller 1/2" ones on my little frag rack, but I had to use 3 pairs per rack otherwise they were too weak through the glass of my 58g tank.

    I bought these 3/4" ones to make new stronger racks, but haven't yet.

    I used epoxy to attach them to the rack, but also found some sort of "plastic crazy glue" that uses a primer and glue. I was sort of afraid to rely on only the crazy glue (the racks I used are polypropelene -ish) to I used both.

    The magnets are only like $2.50 each. So each pair is $5. At worst you need 3 pairs, that's $15, some epoxy and a rack of whatever size you are making.


    Here is some extra advice which may or may not be useful. I used bullet trays for my racks and the sides are smooth ... I had a large snail climb on one rack and overwhelm the two small magnet pairs I was using, thus collapsing the rack (which is why I added the third pair of magnets). I'm wondering ... if you use egg crate to make the rack, if you leave the edges of the rack with the egg crate edges sticking out (versus the smooth sides) will that prevent snails from climbing on it? I mean, if you left the edges ragged versus cutting them down to the smoother face, would that help as an anti-snail device? Hard to explain ... imagine a picket fence with the sharp ends sticking up, versus a fence with a railing on top.
     
  8. denzil

    denzil Webmaster

    Hrm, I'm going to do research again to see if I can create comparable racks. The only upside that I've seen, based on current pricing for epoxy coated neodymium magnets, is that you can set up the rack in any dimension desired.
     
  9. neuro

    neuro Webmaster

    denzil,

    there is a thread on reef central that has a sort of half-assessed instructions; i can find it later, but If you want, I can tell you how i made mines.

    i can show pics later
     
  10. zeroinverse

    zeroinverse Guest


    Vince,
    What thickness of glass does this work across?
    My 150 gal tank is pretty thick, like 5/8" or thicker.
     
  11. Vincerama2

    Vincerama2 Evil Overlord

    My 58's glass appears to be 5/8" thick. I'm just measuring what I can see at the corner of the tank through the front glass.

    Using the smaller 1/2" thick magnets, and a bullet tray, three pairs is barely enough. I mean it works, but if you try and move the rack by sliding it, the magnets will follow but if you go to slow, a magnet will fall off and your rack might fall.

    I bought more of the 3/4" magnets and I'm going to make a larger rack from some egg crate I have.

    Using two larger magnets beats using multiple smaller magnets as it's too hard to move multiple small magnets when repositioning the rack.
     
  12. neuro

    neuro Webmaster

    Here are the resin covered magnets that I made. The next step would be putting in a cut-up egg crate into the resin as it hardened, held up with at least two magnets. A magnet the shape of a bar would work well too.

    [​IMG]

    [​IMG]

    I think I used some pretty thick magnets for this application. For single frags, I don't think I needed such a big magnet.
     
  13. zeroinverse

    zeroinverse Guest

    Northbayreefer on WCR uses magfloats cleaner magnets to create floating live rock shelves on his back glass. Creates a cool floating ledge effect.
     
  14. Vincerama2

    Vincerama2 Evil Overlord

    Ah, so you're not making a frag rack, you are making individual magnetic frag plugs?

    Also ... how are you embedding them? What kind of resin?

    i think the epoxy covered neodynium are holding up well under water EXCEPT for the parts where I accidentally let the magnets slam together and chip the epoxy. I should have re-coated them.
     
  15. neuro

    neuro Webmaster

    I'm coating them in casting resin. you can get it at TAP plasics. i had to buy the mold online. The next step was to make another set with the eggcrate embedded in the resin as it dried. You can also get black dye to dye th casting resin black.

    I also had the problem of them slamming into each other. I had to be extra careful. The magnets and the resin all chip really easily when they get anywhere near each other.

    How are you coating them in epoxy?
     
  16. denzil

    denzil Webmaster

    Cool, that would be greatly appreciated!
     
  17. Vincerama2

    Vincerama2 Evil Overlord

    I didn't coat them in epoxy, I bought them like that. It's a thin black coating, that chips easily when they slam into each other. I'm guessing I should have used some nail polish or something to touch up the chips, but I didn't and I can see rust starting on the magnets that got chipped.

    Instead of embedding the egg crate in the resin, you could probably more easily embed the head of a nylon bolt? Then you can just drill a hole in the egg crate and use a nylon nut to secure it?

    Cool, I've seen that resin at TAP. They also have some molding rubber stuff. I guess you pour the rubber stuff over whatever you want to make out of resin, then cut it open and use it as a resin mold.

    Sounds kind of fun and your results look pretty good.
     
  18. neuro

    neuro Webmaster

    Denzil - I'll type up a full explanation when I get a chance at home.

    Vincerama2 - That's a great idea with the nylon nut. However I'm not sure how I can far I can embed the nut since the casting mold isn't very deep. I would probably have to find a deeper mold. But that's a great idea which prevents me from having to hold an eggcrate in the resin while it's curing. I could have done a better job with the resin, but I was half-assed with time and space. If I had more time, I wouldn't have gotten so many bubbles and lint/leaves/crap in the cast.

    TAP does have other clay/rubber molds you can modify to the shape you want, but with those I *think* you'll need a separate releasing agent (a spray) to coat the impression before you pour your resin--just to get it out when it's done curing. There are polyethurene (sp? or some other plastic) molds that will release without a spray, and that's what I bought online.
     
  19. neuro

    neuro Webmaster

    Denzil -

    You'll need the following:

    - Casting resin:
    http://www.tapplastics.com/product/...ting_products/tap_clear_lite_casting_resin/75

    - Liquid Catalyst:
    http://www.tapplastics.com/product/fiberglass/polyester_resins/tap_mekp_liquid_catalyst/40

    - Neodymium Magnets. I got the 1" x 3/8" ones. Not cheap. I paid about $22 for six.

    - Resin mold. I used these, but depending on your magnets, you can use any mold that fits. TAP plastics also carries this "Castin' Craft' brand also, but they don't carry this particular mold:
    http://store.creative-wholesale.com...ortField/3/Level/2/ProductID/568/Default.aspx

    You'll need to basically follow the directions on pouring the casting resin. Some tips:
    1. Cut the mold up so that you can separate each mold at least 1-2 feet away from each other.
    2. Mix a tiny bit of resin & catalyst and pour one thin layer first into each mold. Let it dry to the consistency of jello. Literally, this is what the directions say and although the directions say X number of minutes/hours, it's really 2-3 times longer than what they suggest.
    3. Remember, each mold is 1/2 ounce, so for the first layer you only need to mix about 1/2 ounce total for the first layer, enough for all six molds.
    4. Do any pouring in an open space. Even a little bit of resin will really stink the place up.
    5. After you pour the 2nd and last layer, you need to let it dry for maybe more than a day or two to really dry and cure.
    6. Don't forget: these magnets can slam into each other even when they're six inches apart. I chipped/broke a few magnets, and got resin all over the place; more than once.
    7. Do all of the pours on an even-level surface.
    8. The magnets will come with separators in between them, so you can pull them apart later. It's best to leave the magnets this way until you really need them.

    Here is the reefcentral post:

    http://www.reefcentral.com/forums/showthread.php?t=1588014

    I hope this helped!
     
    denzil likes this.

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