Helmet hinges and magnets

[Gaz]

I'm currently in the process of finishing off a pair of Iron Man helmets. Previously I've worked with foam but now I've moved on to fibreglass, resin and bondo building.
My intention is to install a set of hinges so the faceplate swings back, and then have magnets to keep the faceplate in the open and closed position. Previously I've been successful with this thanks to the wonder of hot glue, but from reading around I understand that hot glue is pretty lethal to rare earth magnets, in terms of heat causing loss of magnetism?

My plan at this stage is to build a hinge out of plastic, with the strut and the "anchor plates" in the helmet and on the faceplate also plastic. Before I muck up all of my efforts so far, I'm looking for some advice as to the best way to attach this plastic to the resin interior of both pieces. Similarly, what adhesive should I use to attach the magnets? I was considering resin, but would the heat from the curing process once again cause the magnets some issues?

Thanks in advance!

 

[LarryD]

Back when I was playing warhammer I would just use a nice super glue to mount the rare earth magnets into resin and plastic. Since I was typically trying to stick them into small holes in models I would use a small drill bit to control the magnet and keep its orientation then after the glue set up a bit you can just spin it off.

 

[Jon Kelley]

While epoxy curing is exothermic, I don't see as it should have a significant effect on magnets (I helped my granddad build an aerobatic ultralight - 1" thick styrene foam, 1/8" ACX plywood, tuxedo taffeta to coat it - all bound together with epoxy. Didn't melt or dissolve the foam at all - while I don't recall what sort of epoxy was used, it should be readily available from some outfit like Aircraft Spruce & Supply or Wicks Aircraft Supply.) You can also do a "proof of concept" by mounting a magnet, using epoxy, into a scrap of wood - then testing the pull. CA glue may also be used, but it may not give as much retention as you would need (the magnets aren't porous.) And, "hot glue" can now be had in "low-temp" and "high-temp," but I don't see as either should be hot enough, long enough to screw with Nd or Sm-Co magnets (I think I've used hot glue to fix these magnets in place before with no ill effects, but it's been some time. And the magnets cost a good deal more, then... ) CA glue, I believe, won't be very effective with resinoid plastics - rough up the surface and use epoxy? Been a bit, but that's what I'd do (use a 240-gr or 320-gr square to rough up the surface, this can help the adhesive stick better than on the smooth surface.)

 

[laellee]

High-temp glue can demagnetize, but it is pretty challenging to do. My hot glue gun is 80 watts (most are 10-40), and I've gotten away with gluing Nd magnets without a problem.

Now having said that, I don't hot-glue them anymore because I don't trust the bond. I've also had problems with CA glues holding securely, so now I just use two-part epoxy adhesives and they work great.