Windscreen secured by magnets

[David Moreno]

I was wondering if anyone has tried using magnets to secure a winscreen for a pot?

I thought of the idea after loosing one of my paperclips twice.

They would have to be high heat epoxied or JB Welded in place, but I thought that once done, there would be one less thing to loose.

I understand that it would make my windscreen weigh a little more, maybe 0.1 oz more at a maximum.

Just curious.

Edit: I should note that my windscreen is 0.03mm titanium material like the one that used to be sold here at BPL.

[Glenn S]

Well, heat causes loss of magnetism, so not sure where the boundaries would lie with a windscreen, but it's rather moot since neither aluminum nor titanium are magnetic. That only leaves steel, which is a little heavy for around here…

[Ben Smith]

From the fact that the OP used plurals quite a few times I had presumed he meant to attach opposing magnets to both parts of the windscreen.

[Marko Botsaris]

Two words – extra paperclips.

[Colin Krusor]

I agree with Glenn; the only potential problem I can imagine is that the windscreen might not stay in place if the placement of the magnets exposes them to heat. The strongest magnets per unit weight are neodymium iron boron (NIB), but these start to loose their magnetic properties even at boiling water temperatures. Samarium cobalt (SmCo) magnets work better at somewhat higher temperatures, but they are inherently weaker than NIB magnets. Both kinds are available in a variety of sizes on ebay.

[Kevin Beeden]

slot and tab

[Kevin Beeden]

Are magnets less likely to be lost than paper clips? Maybe putting them on a steel gas canister?

IIRC, Trail Designs had magnets as a means of closure in their original patent application. Can't remember if it carried over to the granted patent, or whether, like a lot of other stuff, it got cut out.

[Colin Krusor]

I agree with Kevin that slots and tabs are good alternatives to magnets, but they are more fiddly. I made a little woodstove with 0.005" Ti foil (a very brittle 15-3-3-3 alloy that was prone to cracking), and the slot and tab method worked great:

I still think that your magnet idea is a good one, though. Also, an idea occurred to me. I recently placed a NIB magnet in a flask of boiling water in my lab, and held another NIB magnet to the outside (where it was cooled by the air). The force of attraction was weak because one of them was hot. If there had been a hotter liquid in the flask, there would have been no force between the magnets at all. Then I removed the magnet from inside the flask and put a steel pellet into the flask. The attraction of the steel pellet to the cool magnet on the outside was not affected by the heat of the boiling water; the force seemed (subjectively) to be about the same as the coercive force between the two outside the flask.

You could put a piece of steel on the inside of the windscreen, where it is hotter, and the magnet on the outside, where it is cooled by the air. They could both be epoxied in place. An interesting property of magnets: the coercive force between a magnet and a piece of steel is exactly the same as between a magnet and another magnet when the two are pressed together (the distance between them is zero), but the pair of magnets retains more of this attractive force as the distance between them increases than the magnet and the steel. So, when the two are very close (separated only by a thin metal foil), the force between a magnet and a piece of steel will be about as strong as that between two magnets. I assume the composition of the steel might affect this, but probably not enough to make much difference for this application.

[David Drake]

This worked for me, and should be lighter than magnets:

http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=22027

[Jon Fong / Flat Cat Gear]

Snaps work great if you know where to place them as they can anneal and loos force.
They also can be used on aluminum but work best if you use heat treated aluminum (I use 6061-T6)
BTW, I use stainless steel and and at the right thickness, it can be LESS weight than aluminum. Also, a lot of SS is non magnetic so you would need to use 2 magnets (and the field strength does drop with temperature)

Best regards,

Jon

[David Moreno]

I have a few little round magnets that used to hold small bag clips onto the refrigerator. The plastic spring part gets brittle over time and they break. I've saved the magnets from these.

I was worried about the heat making them loose their magnetism too, so I put 4 of them onto a cookie sheet and put them into the oven for 15 minutes @ 450 degrees F. When I took them out, I immediately tried to stick them together, and they stuck… even with a double layer of titanium between them. This wasn't an ultra strong bond, but good enough (I assume) to hold the windscreen in shape around the pot.

Yes, I was referring to epoxying them on opposite sides of opposite ends of the titanium windscreen material, so that the windscreen overlap section would have no air gap.

Edit: As some of you know, I was supposed to be thru-hiking the AT as of 2 days ago but was involved in an auto accident (head on collision with drunk driver) and now have a broken leg. I'm just trying to keep busy tinkering with outdoor gear until I can get out and hike again.

If my magnet idea doesn't work, I'll consider the tab idea.

Thanks for all the input guys.

[Kevin Beeden]

Colin, that's a very nice-looking windshield, but a bit more complicated than I had in mind… I guess it's a variable diameter?

My slot and tab suggestion was for a simple, fixed diameter closure that I've used for my design scripts that zenseeker now hosts at ZenStoves. A simple slot (gap) cut in overlapping ends of a windshield, at the top edge of one end, and bottom edge of the other end, with mating folded tabs at the other edges. these simply slide into each other and make a stable connection.

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