Friday, September 10, 2010

Scary magnets


My magnets to secure the solar panel came today, accompanied by one of the scariest health warnings I've ever seen!! The four page leaflet includes all sorts of danger warnings, including detailed description of what can happen to your fingers if trapped between two big neodymium magnets. Only hydraulic cramps can pull them apart.

My magnets however are relatively safe, being ferrite and having a pull of 18kg each. That should be enough for four of them to secure a solar panel on a steel roof. Neodymium magnets of the same size would have a pull of 6okg each. Try pulling them off the roof. As for the next size up, they pull 155 kgs! These are seriously dangerous objects and have to be kept at least 500mm apart. They will sever your fingers, stop your watch and your pacemaker, wipe your credit cards etc from some distance.

I will have to use stainless steel screws(relatively non magnetic) to attach them to the panel and I suppose I may need non magnetic screwdriver/ spanners too in order to fit locking nuts. Hmmm.

I can see that I will need to be very careful in putting them in position on the boat roof. Apparently the idea is to put a plastic or nylon spacer in between the magnet and the steel surface and then slide it out when in position. I think I'll make a wooden handle to lower the magnet down on its screw.

Meanwhile I await the man delivering the solar panel.

7 comments:

Anonymous said...

Wow, they do sound scary - I'm sure Richard will put some on order straight away!

Sue, Indigo Dream

VallyP said...
This comment has been removed by the author.
Anonymous said...

Impressive, Neil, but even 18 kgs would be seriously uncomfortable landing on your pinkies!

Anonymous said...

Impressive, Neil, but even 18 kgs would be seriously uncomfortable landing on your pinkies! VallyP
Sorry, there's something weird going wrong with blogger.

rainman said...

Have you considered how you will move or remove these super-magnets once attached Neil? David.

Neil Corbett said...

Yes. As they will have a stainless steel bolt projecting up from them, I can attach a tommy bar and lift two handed. Even at my advanced age I reckon I can lift 18kg. Also I intend to try a small disc of silicon oven tin liner beneath each one to allow a bit of slide. The warnings in the leaflet refer mainly to much stronger magnets than the ones I bought. I hope.

Halfie said...

I expect you'll find that the magnets aren't quite as difficult to pull off as the warnings indicate. There are some extra factors weakening the attraction: the thickness of the paint on the roof; the curvature of the roof; any slight unevenness in the roof. Putting a piece of plastic under the magnets sounds like a good idea to prevent scratching (and hence rusting), as long as it's not too thick so as to diminish its effectiveness too much.

To pull it off the roof I would think that all you'd have to do is use the protruding bolt (and an extension, probably) to tilt the magnet on its edge. Then it'll come up easily. Possibly.