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Hi there, Dakkanauts. I come to the experts on painting and modeling with a problem that's been troubling me for the past few weeks. I recently put together 6 Killa Kan models and opted to magnetize the arms, so I could remove them in-game for weapons being destroyed (as well as for some on-the-fly posing). My problem is, the magnets don't stick very well. Every week, I have to re-glue at least one magnet onto an arm so it will continue to stick. While I like having the dynamic poses and being able to show weapon destroyed results, it's getting to be a serious pain. Is there anything I can do to make them stick easier?

I'm using Zap-a-Gap glue (Medium CA+, the green colored container) and I believe 1/4" rare earth magnets. I'm not 100% sure on the magnets - I do know they were the smallest ones offered by my FLGS, and while they work like a charm, they have an irritating tendency to come unattached on a nearly weakly basis. I'm not sure how glue reacts with weather, but is it possible that the glue could have a weaker bond in cold weather? I do tend to leave my models in the trunk of my car, and it's now approaching winter here in Minnesota.

Any advice would be great. I'm in a rut here.

Hi,
I'm using UHU Strong & Safe for my magnets and i never had any trouble with it.
I even magnetised my Harlequin jetbike (heavy metal) and I never had to re-glue the magnet.
Try it and let me know if it's fine for you too.

I have a similar problem as the op when using magnets on magnets. Most magnets are too strong for modeling uses. I have switched to using magnets on rubersteel and since the pull is less my problems are also smaller.

I use 3x1mm magnets for my conversions.

Drill out the hole using a 3mm drill bit (normal size for a regular power tool).

Put a small ball of greenstuff into the hole and slightly pack it in. NOW put a drop of superglue into the hole and then insert magnet.

Started doing stuff this way early last year and they've stayed where they were put since.

Anything larger than 3mm and superglue just isn't strong enough to hold the magnet from another magnet's grip.

i use 3x1 magnets, they work a treat, i use loctite, the runny stuff, it has never failed me.
which caused some issues when i glued one in the wrong way...

Another tip I can give you is that when you detach a magnetized item from the model (say e.g. arm from a killa kan) dont PULL the magnetized part away, SLIDE the part off the other magnet (hopefully my poor ASCII art diagram will explain:
Dont to this:
PULL <--------- ----------> PULL
----ARM---:MAG:~:MAG:---BODY---
PULL <--------- ----------> PULL

Do this:
^^^SLIDE^^^ vvvSLIDEvvv
----ARM---:MAG:~:MAG:---BODY---
^^^SLIDE^^^ vvvSLIDEvvv

This is because magnets have a lower shear strength than a 'pull' strength, so pulling on strong magnets may be enough to rip the other magnets out of it's fixings without breaking the magnetic attraction, but by sliding in off it's much easier to break the magnetic attraction in the perpendicular direction (shearing), hopefully allowing everything to stay glued

I also drill a small hole of the same size as the magnet and then glue the magnet in with superglue (as long as the hole is the correct size, I don't use Green Stuff). After the magnet is in, I put a thin layer of superglue on top of it in order to protect the magnet and to keep it in place.
I did this with magnets up to 4x1 and 3x2 mm (300g pull), and no problems so far.

I use ZAP-A-GAP and its damn good. One way of checking is to attach the magnet (correct orientation) then put a piece of paper there and place other magnet arm on with the paper between them. Let it dry for 48hours. Then tug at Paper and the arm will come away more easily without you having to put directly on the seated magnet.. I have done this alot and the magnets always stay seated. Consider using bigger, flatter magnets too (if possible).

If you are constantly attaching and removing arms then the contact shock betwen the magnets can cause the glue bond to fail. I woudl also say that the weather could be a problem if it is getting really cold. One of the main methods to dissassemble models taht are glued together with superglue is to stick them in the freezer and allot thermal contraction of the model to break the glue bond.

OP, Can you post a pic or two of how you mounted your magnets. That will help us give you the right answers. I drill a slightly larger hole than what I need, pack it with GreenStuff and then seat the magnet. If the magnet comes out after the GS cures I then use a thin superglue to glue it. Using GS helps make sure you have a real good socket for the magnet. DO NOT put superglue directly on new/uncured GS it can slow down or even completely inhibit the GS cure.

The best place I have found for magnets is here http://www.kjmagnetics.com/products.asp?cat=10 I buy all of my magnets from them, and I have magnetized most of the armies in my sig.

I actually drill a hole just slightly SMALLER than what I need. Then drop some Zap into the hole and use some smooth needle nose pliers to press the magnet into the hole, that way the plastic is smashing the magnet in the hole and it won't come out.
It can get tricky if you have details on the outside that you don't want crushed but some rubber, like from a sliced up inner tube can help cushion that.

Another trick is to only use a magnet on one surface and steel on the other. Like for my dreads I attached a plain steel washer to the dread itself and put the magnets in the arms so the magnets just stick to the steel instead of having two magnets pulling at each other. You can get some pretty small washers so you might try that.

Actually I have started to use steel as Rare Earth magnets are expensive so to be cheaper I am starting to use steel washers or cut out the centre of pieces of thin steel using a press.

Leigen and Flinty both point out potential reasons why the magnets might be jumping ship - extreme cold weakens superglue bonds by causing them to become (even more) brittle, so repeated stressing due to pull perpendicular to the plane of the join could reasonably break the already strained bond.

I've never had a problem with magnets popping out, but I must admit that my models are rarely exposed to extreme cold (or any extreme differences in temperature within a short span of time). Ensuring the magnets are seated snugly would be my first line of defense. A GS "cradle" would, I imagine, be perfectly effective, but I opt for the "snug fit" method - if the magnet doesn't seem likely to go anywhere once you jam it in the hole, any adhesive is just additional insurance (I haven't had any issue with Krazy Glue from the dollar store).

Granted, I also tend to use smaller magnets, relying on mechanical means for the bulk of the support and using magnets simply to keep parts in place. Using Kans as an example, I would likely use a central pin from the shoulder into the body socket, with an offset pair of magnets to hold the arm at the proper orientation. If I wanted options for the pose, a suitably sized washer would be inset into the body socket, instead of a corresponding magnet, allowing the shoulder's magnet to grip something, no matter the angle. This would be impossible with 1/4" magnets, but using something half that size makes it not only possible, but rather convenient (easier to install, and one can simply use more of them when necessary - the only time I've needed to increase size, thus far, is to attach titan-scale weapons on a scratchbuild).

^This.

I keep the arm mounts on my dreadnoughts.
I put a washer over it and magnets go into the arms.

This way, the arms can still pivot around the central pin, but the two magnets hold it in place and stop gravity dragging it down (metal dread, metal arms).

Wow, just a day and already plenty of helpful advice. I did notice that it's far more likely to break the bond if I pull them straight off, rather than sliding them off. Even with that, though, one of them tends to just snap off as soon as I try to put it on.

Images of the magnets on green kan:




Like I said, I would have used smaller magnets, but those sized ones were the smallest offered at my FLGS. I also don't have a drill, and am already shaky enough to be nervous about using one, hence why I don't tend to drill holes for magnets.

I'll say this, looking at the detached parts, it does look like the glue has expanded quite a bit from the dab I actually put on - does that normally happen with superglue? (I use plastic cement for most modeling work)

Another problem is that the contact area is very low. Because it's rounded, every time you try to pull the piece off, you stress the glue, and the actual contact point is small. You should get better results just filing the arm down and gluing to a flat surface. One other reason why drilling and then gluing is effective is because you also get a much larger contact area.

for my own, have a big mechanized sw army all magnetized, my brother DE army magnetized too, just use correct size hole for magnet so they tight, put some gw superglue and Voila! job done never got a magnet come out..

If a drill is out of the question the try grey hamsters tip and file down the arm pit for more surface area.

Ah, pics say it all - small, rounded contact point for the arm-side magnet. File the ball down a bit so you're gluing the magnet to a larger, flat surface and you should have far fewer breakdowns. The angle at which it's mounted is applying torque to the join simply from the weight of the arm, so you'll want as strong a bond as you can manage. Sliding/twisting the arm off instead of pulling will still help, but a stronger bond should keep that from being an absolute requirement.

Locclo wrote:Like I said, I would have used smaller magnets, but those sized ones were the smallest offered at my FLGS. I also don't have a drill, and am already shaky enough to be nervous about using one, hence why I don't tend to drill holes for magnets.

I assume you're nervous about using some kind of electric drill. Get a hobby drill, it's a hand drill which is easily controlled and should chew through plastic like no-one's business.



Just make a small indentation in the centre of the area you want to drill so the tip can sit in the hollow and then spin away.

I agree with all above. Your magnets are way too big and they're attached at way too small a point. Shave the ball down so it has a nice broad surface to put the magnet on.

Though with magnets that big, you should just switch the arms to regular metal. You've got PLENTY of pull with one that big.