Uses and Abuses of Neodymium Magnets

Got a question about techniques, materials or other aspects of physically building a model? This is the place to ask.

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DeltaVee
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Uses and Abuses of Neodymium Magnets

Post by DeltaVee » Mon Mar 27, 2017 8:37 pm

What experience do you have using neodymium (rare earth) magnets? There must be hundreds of uses: attaching battery doors, hatches, weapons, docked shuttles, and so on. I shamefully confess a certain affection for the "toylike features" of yesteryear's models. I've bought neodymium magnets and magnetic paint from a local craft store but never used them till the Zvezda Star Destroyer. Now I plan to use them for attaching a scale Millennium Falcon, Imperial Shuttle, Slave One and a Blockade Runner.

I ordered some 1x1 mm magnets that easily fit into even those tiny models. I started with the Falcon and the back of the Star Destroyer bridge. But I needed a larger magnet inside the bridge. When I pulled out a pack of magnets I'd been storing for years, they were covered in presumably metal "fuzz" and I'm not sure where it came from, perhaps the nickel coating? I searched here but didn't find anything, so I started surfing for info and came across this:
http://www.kjmagnetics.com/FAQ.asp

It seems like about everything I could ask but wondered if you all have any personal experience with uses, adhesives, etc. you'd care to share? A couple of experience sofar:
1. rare earth magnets are so strong they can pull the iron out of magnetic paint, so you need to overcoat a magnetic layer with something. I'm not sure even that would work in the longterm, but it seems like the only option for a model covered with detail.
2. I assume you have to line up the poles on 2 pieces you plan to attached or you'll wind up repelling them.
3. I secured a 1x1 mm magnet by sinking it into the underside of my M. Falcon and supergluing it but I wonder if it will pull right through the superglue?
Mods, if I somehow missed a magnet thread around here, please move. Thanks.

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SpaceRanger1
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Post by SpaceRanger1 » Tue Mar 28, 2017 10:23 am

I've considered using them but have no practical experience as yet. One thing I've thought about is to make an entire hull section removable by cutting along an existing panel/contour line so as to expose the interior. I was thinking more of airplanes in this context but it should also work for starships.

One thing you can do is to use magnetic sheet material as half of your magnetic pair. This can be cut to custom shapes with scissors or made into discs with hole punches. The material is vinyl, however, and may react with kit styrene, so if you use it, its location should be primed/painted to prevent any chemical reaction. Magnetic sheet can be purchased at craft and office supply stores, but it's the same stuff used for refrigerator magnet business cards and calendars, which are free and probably provide more than enough material. Using this material with a magnet also creates a "gentler" bond than the use of two magnets in combination, making it easier to remove your removable item without damaging it.

(Trivia: refrigerator magnets are technically "one-sided flux magnets," which are known as "Halbach arrays." Use the term in conversation with your modeling buddies and impress them with your erudition!)
Michael McMurtrey
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Kylwell
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Post by Kylwell » Tue Mar 28, 2017 11:14 am

1. Why are you using magnetic paint and where do I buy it?

2. Yes. I usually epoxy one in place then add the other other where it will need to be and let it autocorrect. Then glue it in.

3. I usually try to go inside to inside, letting the plastic support the pull but if this isn't possible your way should work fine provided there's no gap between the magnet and supporting surface (i.e. the Star Destroyer neck). These magnets are powerful enough to crush a 1/350 TOS Ent shuttle.
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naoto
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Post by naoto » Tue Mar 28, 2017 11:54 am

IIRC the Ultra Hawk kit (vehicle from Ultraman series) used magnets to hold together the different component vehicles together (it was essentially three vehicles that "docked" into a single vehicle). IIRC there have been a number of people who used similar techniques with magnets for Star Trek vehicles such as the NCC-1701 D kit to allow the saucer section to be undocked w/o worrying about the mounting pins breaking or loosening.
You'll often see these magnets being used to hold down access hatches on R/C model planes.
Naoto Kimura
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fritzthefox
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Post by fritzthefox » Thu Mar 30, 2017 2:49 pm

Magnets can also make useful clamps, where ordinary clamps cannot reach. I used them a lot building a suit of stormtrooper armor.

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jgoldader
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Post by jgoldader » Sun Apr 16, 2017 6:19 am

I used them on a SpaceShip2/White Knight combo I did a few years back, so the little rocket plane could be separated from the carrier. Drilled holes, dropped magnets in, used Aves to seal in place. By having the magnets separated a mm or two, you greatly reduce the force. Am using them on a lighted build currently, to hold a major subassembly to the rest of the model so I can get into where the Arduino will live to reprogram/etc. if needed. The ones I'm using now had 3M stickum on them, and they stick really well.
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b5ranger99
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Post by b5ranger99 » Sun Apr 16, 2017 2:34 pm

If you want an inexpensive source for large versions of the magnets look for "dead" hard drives. You need to tear them apart CAREFULLY however there are usually 2 large magnets in each drive. I have had people "donate" their dead drives to me, since I assured them the data would not be reasonably available to anyone.

FYI The disk platters make nice wind chimes.
"When others do a foolish thing, you should tell them it is a foolish thing. They can still continue to do it, but at least the truth is where it needs to be."

Dukhat, Babylon 5

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