Magnets strong enough for caching

[lemmykc]

Hi there,

I have been Geocaching for about 16 months now and in my timeI have seen many magnetic caches. I have been looking in many different hardware stores for magnets that you can just buy and stick in an eclipse container or sistema container, but I cannot find one . Can I please have an idea of what magnets people use, the price and where they get them from? I would really like to hide a magnetic eclipse or a sistema container.

Thanks
lemmykc

[caughtatwork]

Magnets from inside old, dead HDD (hard drives) are the best thing ever. They stick like nobody's business. You could try your local computer shop and see if they have any dead drives they want to dispose of.

Rare earth magnets are better than ferrite magnets. The rare earth magnets are generally coated in nickel and look silvery and shiny. Ferrite magnets are generally a dark grey color.

If you can stack enough ferrite magnets together you can get them to hold, but their pull is still not terribly strong. The only success I have had with sticking ferrite magnets to anything is to glue them down, then cover them with gaffer tape. The glue is not strong enough to hold he magnet in place and the flexing of the plastic on a sistema container means that quite quickly the glue breaks away. Covering them with gaffer tape ensures that they cannot pull away from the plastic box.

On the bottom of a 200ml sistema container I use 6 ferrite magnets like you can get from hobby shops or places like Bunnings in the craft aisle (sometimes).

Rare earth are the best. This is a good site to check out their pull value. http://aussiemagnets.com.au/magnets/Rar ... dymium%29/

e.g. This type has a pull value of 1kg http://aussiemagnets.com.au/product/--6 ... th%29.html i.e. In a direct pull it would hold 1kg. Rare earth magnets are pretty pricey though and you need to consider that they will need to exert their magnetic attraction through your eclipse tin or container. The thicker the container, the more pull you need to get.

I have had success with 6 of these http://aussiemagnets.com.au/product/-10 ... th%29.html attached (glue and gaffer tape) to a 200ml sistema container. You can get them in bulk lots from ebay sellers and http://s.dealextreme.com/search/magnets for around $0.20 each. So you'd be up for about a dollar for enough magnets to attach to a 200ml sistema.

Obviously the larger the magnet, the better the pull, but the higher the cost.

[budgietas]

Rare earth magnets are certainly the best. I have found the best place to buy them is

http://www.dealextreme.com/c/rare-earth-re-magnets-1105

This place is fairly cheap and although they are not very large, a couple together next to each other are more than sufficent to hold a cache. I have used these on the outside of the eclipse tin, held on with tape and then spray painted. I know people hate eclipse tins, but they have there place!!!

[lemmykc]

So if I attached around 10 of these to a 200ml sistema, it would stick? http://www.dealextreme.com/p/super-stro ... pack-13516

Another question: Does the other end of the magnet (where you actually stick the container to) make a difference?

[covert]

Try these
http://www.dealextreme.com/p/super-stro ... pack-10305

10mm x1mm = volume of 78
20mm x 2mm = volume of 628.

In a perfect world expect 1 of the larger ones to be close to 9 times stronger

[caughtatwork]

Try these
http://www.dealextreme.com/p/super-stro ... pack-10305

10mm x1mm = volume of 78
20mm x 2mm = volume of 628.

In a perfect world expect 1 of the larger ones to be close to 9 times stronger

I wouldn't.
10x1.5 = 960gm pull
10x3 = 1.9kg pull
10x5 = 2.8kg pull
20x3 = 4.3kg pull

I have used the 10x1 for the outside of a cache. 6 were adequate, but 10 would be better. Remember anything between the magnet and the steel you're attaching it to will decrease the pull of your magnet. Gaffer tape seems to reduce the pull quite a bit (unquantified), so the more the merrier.

If you're sticking these on the outside, then watch out for the lip on the bottom of the container. It's higher than the thickness of the magnet. You will need to put something under them against the container to raise them up so they sit above the lip (or shave the lip off).

HDD magnets are the best if you happen to be able to find one or have a caching friend who will give you one.

[covert]

Try these
http://www.dealextreme.com/p/super-stro ... pack-10305

10mm x1mm = volume of 78
20mm x 2mm = volume of 628.

In a perfect world expect 1 of the larger ones to be close to 9 times stronger

I wouldn't.
10x1.5 = 960gm pull
10x3 = 1.9kg pull
10x5 = 2.8kg pull
20x3 = 4.3kg pull

There is an error in my math. 628/78 = 8. So it should be 8 times since the strength of a magnet (in a perfect world) is directly proportional to the size of the magnet. However your figures taken from our imperfect world do not match the science.

[gmj3191]

A lucky cacher in Brisbane who is prepared to pick up a box of 13 hard drives from Chelmer may
be interested in this item on eBay
http://cgi.ebay.com.au/ws/eBayISAPI.dll ... 500wt_1156

[chillibutts]

Hi there,

I have been Geocaching for about 16 months now and in my timeI have seen many magnetic caches. I have been looking in many different hardware stores for magnets that you can just buy and stick in an eclipse container or sistema container, but I cannot find one . Can I please have an idea of what magnets people use, the price and where they get them from? I would really like to hide a magnetic eclipse or a sistema container.

Thanks
lemmykc

Yup - I got mine online from Aussie Magnets - I went for the discs, 4.5kg pull - been VERY happy with them

[lemmykc]

OK, so lets say I got this product, how many would I need to buy to to hold up a 1 litre sistema? Remember, I am 13 and have absolutely no knowledge on this, so be easy on me

[gmj3191]

OK, so lets say I got this product, how many would I need to buy to to hold up a 1 litre sistema? Remember, I am 13 and have absolutely no knowledge on this, so be easy on me

Liam, I have a HDD magnet you can have for that job.

[garnercx]

I have been Geocaching for about 16 months now and in my timeI have seen many magnetic caches. I have been looking in many different hardware stores for magnets that you can just buy and stick in an eclipse container or sistema container, but I cannot find one . Can I please have an idea of what magnets people use, the price and where they get them from? I would really like to hide a magnetic eclipse or a sistema container.

I have a box of hard drives here I use for caching. If you want a couple, you can swing past South Melbourne and pick them up. I also have the torx screwdriver you'll need to open them if you don't have one.

[chillibutts]

OK, so lets say I got this product, how many would I need to buy to to hold up a 1 litre sistema? Remember, I am 13 and have absolutely no knowledge on this, so be easy on me

I reckon 2 of those would do it if on the outside of the container... if on the inside then personally I would use 4. But perhaps that is overkill - but you want it to stay therer ... right.

[caughtatwork]

Very heartening to see the community come to the assistance of a young geocacher. HDD magnets are the best and your cache will be the better for it if you can grab one that has been offered.

[PesceVerde]

A lucky cacher in Brisbane who is prepared to pick up a box of 13 hard drives from Chelmer may
be interested in this item on eBay
http://cgi.ebay.com.au/ws/eBayISAPI.dll ... 500wt_1156

Thanks for the heads up on fleabay item; I'd been looking for some HDD magnets. Made a modest bid but if someone (cacher?) else is more interested, ...