Magnetizing a section of 3/16" chain

You could pass it through a very strong magnetic field. How long it lasts depends on the chain material and how you magnetize it. It also depens on how you connect the chain. If you want to magnetize a SECTION of a longer chain, it will not last at all because it would dissipate into the rest of the chain if there was no isolation. If you are going to attach the chain to some non-magnetic material, it will hold it for a while, but as I said, how long will depend on the chain material. You can make it last longer by super heating it while magnetizing it, but that may affect the tensile strength of the chain.

Why don't you state your purpose a little more clearly.

The device is to drag through water to collect old nails and other small metal objects that can be picked up.

I want the chain to conform to the bottom and make a wider sweep than a metal rigid magnet that just buries in the mud and twists and turns........

What is the easiest way to magnetize this chain so it will be the strongest and last the longest?

* i don't have access to a big magnet or a furnace to heat it in, but i could touch it with a torch for awhile...any and ALL ideas welcomed!

If we wrap copper wire around an iron rod and pass current through the copper, the iron will become magnetized, right?

If we substitute the steel chain in place of the iron rod, will the chain become magnetized?

Perhaps using a 3/8" steel cable instead of the chain.

If the entire assembly was then inserted into a 3/4" section of nylon air brake line to protect the copper windings from damage, it might be workable.

Use a separate 100 amp alternator to run the current to the copper.

Does anyone know a formula for determining how may turns, how much amperage and any other details?

(Any hydrogen generated by this should be ignored. It is not worth opening that can of worms again.)

I'd like to stck with chain if possible.

I need the chain to be bare when it touched the mud.

Any idea if this could be done with a regular car battery?

What size wire and how close do the wraps need to be to the chain?

I think it was 100 turns of wire and a D cell battery with a nail inside the wire.

Try going to Radio Shack and get a roll of bell wire. Take a short length of the chain and wrap 100 turns around it. Connect it to a D cell and see what your chain does. At this rate of turns, a 12 volt car battery will just heat the wire till something burns.

If it does work, how will you protect the wire from damage?

Thank you Bob,

Do i need the wire to remain on the cable to keep it magnetized?

creole

For all practical purposes. Yes.

I doubt you can magnetize chain like that enough to pick up nails etc. without a large power source. You would be better off attaching a bunch of pre-made magnets to the chain and let them drag behind. An alternative would be to have chain made from magnetic material. Probably hellashishly expensive though.

And then you will also have the problem of getting the nails off of the chain (or magnets) once you pull it from the water.

A suggestion would be to use a semi-taut cable, then string cylindrical magnets along it, essentially like roller cable. Then when the cable is dragged along the bottom, the magnets can roll around the cable to help prevent them from catching on things, but the cable makes it flexible enough to conform to uneven surfaces.

Roller magnets...... an idea NOT foreign to nets and such......(ie: roller rigs for trawls, mud rollers,.........)

Any idea where I can find a cylindrical magnet with a hole in it?

Thank you for idea. the magnetized chain idea was one venue, but I wanted to bounce it off you guys as I am quite ignorant in that area.

Smitty

The problem you'll find is that the magnetic poles point the wrong way. Try this with any cylindrical magnet. Try to pick up nails, for example, with the side. The strength is always at the ends.

The orientation of the poles is at the flat ends....NOT along the curvature..........

Any other ideas on magnets and shapes?

Are the rectangular and rod type magnets the same way?

Most chain is not hard enough to store any significant magnetism. If you found a chain that could be magnetized, where would the poles be? The nails will only be attracted to Exposed Poles.

The one solution that occurs to me is this:

You cut every other link of the chain on one side. Obviously this weakens the chain significantly, but I gather you are not trying to recover ship anchors...

The cut provides exposed poles, and also provides a gap through which you can feed the copper for winding a coil of wire on the other side of the link. I've shown the coils connected in series, but depending on the size wire and number of turns used to make the coil, it would be possible to wire them in series-parallel sets to obtain optimum operation from whatever voltage source is available. Be sure to allow enough extra wire between coils to allow for flexing of the chain.

The entire chain would be enclosed in a piece of rubber or plastic hose split lengthwise (Blue in drawing). Use a plastic cable tie (not shown) around each of the complete chain links to hold the hose in place and hepl keep the magnetic poles exposed.

A fair amount of hand work to produce, but I think it should work. of course you would disconnect the power to release the recovered objects.

DK,

OK........

How many wraps of wire?

What size of wire?

What type electrical power (amps ?)

This is do-able too.

Thank you for the drawing and the time.

Smitty

If I may ... the concept here isn't bad, but if you're going to that much trouble, look at all the ways to MAXIMIZE your return (flux leaving/entering poles), rather than giving any of it up.

[ Reddish "retention-bars", to prevent horseshoe-mags from slipping-out...non-magnetic.]

...epoxy-encapsulated coils, and braided-sheath with slippery chafing gear over top of wiring.

You have a good point. I was trying to keep it so the chain links couldn't come apart, although if tied right, the split tube should prevent that. Here's a compromise:

Grind each magnet link until it is thin enough to bend out a bit, cut it (easier now that it is thin), bend it out a bit, then grind flat. The links still can't come apart, but the narrow gap ensures a maximum flux, while the thin tips ensure that most of the field does not go straight tip-to-tip, but rather out where it can attract the debris, and the large flat surface should help hold better.

Smitty, as to the windings, you need to use magnet wire (solid copper with a layer of varnish insulation (thin insulation to get maximum of turns in minimum of space - wire made recently probably uses a thin plastic coating rather than the varnish that used to be employed)). Somebody in an earlier post suggested a hundred turns - that's probably a good starting point. I'm picturing a chain where each link is an inch or so long, as larger links would leave too large a gap between magnetic pole pairs. In that case, wire in the #18-#22 range would be a good size. I suspect each coil would take something around 1-2 volts; larger coil wire = lower voltage, higher current. If this is the case something around 6-12 links connected in series should work on 12 Volts. Note that higher current will mean stronger magnetic field, but more heat and shorter battery life (assuming you are dragging this from a boat). Since you are going to be using this under water, the heat is probably not much of a concern. Use much larger wire leading from the battery to the coils. For longer chain, make several sets of 6-12 links connected in series, and connect the sets in parallel with each other. This means you will need larger stranded wire running along to the parallel sets.

Hopefully you have a variable DC voltage source available, so you can make a single link and test it for appropriate voltage and current to get the attractive strength needed. Otherwise, you are going to have to make something like a dozen links, and experiment with the battery. Start with many links all connected in series, and if you don't get enough current, then reduce the number of links until you do. Then make multiple sets of that many links and connect the sets in parallel. Of course you must scrape the varnish/plastic off the ends of the ends of each coil so that they can be soldered to their neighbors and the supply wires. Don't use crimp connections under water.

Tom's suggestion to encapsulate the coils in epoxy is a good one, once you have determined the size and number of turns that works best.

Good Luck!

Dick

Dick,

I understand the voltage vs wire.....

Thank you for th break down of 'how to'

Thank you very much

Smitty

Good picture and understood.

Smitty

Definitely a "can of worms", here ... numerous good responses so far.

FWIW (in response to OP questions) trying to create Longitudinal Magnetization into individual chain links (circular, more-or-less, in geometry) is not going to be efficient at all. Your magnetic strength and it's longevity would depend on a number of factors including the applied magnetization current and the retentivity of the particular grade of steel, not to mention it's exact dimensions and weight...

The post suggesting tying other magnets to "drag lines" behind your chain is probably your best idea for conforming to bottom contour. The biggest challenge will be insuring that each individual magnet will have the strength to lift the articles-of-concern (nails/screws shouldn't be too much problem), WHILE insuring that the trailing-lines cannot permit the entire complement of magnets to grab-on to each other, bunching-up so as to eliminate effectiveness of the array.

How deep is the water you want to do this in? Any thought to using an U/W metal-detector as an initial option...?

Best Regards ~

NDT,

OK. the trailing lines are a consideration. They will tangle up with one another if too clsoe but too far apart and I miss too much area.

Water depth is 5 feet max but covers 1/2 acre.

We want to eliminate metal before a geotextile liner is put down.....I know they are tough but who wants to take a chance with THAT much water in place....

Thank you for the time and feedback.

Smitty

thinking like , trailing-arrays-akin-to-flocks-of-geese... < < < <

flocks of geese.....

ha ha ha .....but it make sense.......

thank you too.

With these ideas we will find what we are looking for.

Thank you all.

Smitty

Really wasn't meant to provoke a laugh ...... I am certain that I actually SAW something like this once-upon-a-time. Picture THIS , using stiff (but still flexible, and hinged) "straws" for conduit-connections between each V-array. The stiffness factor keeps magnets all aligned properly, preventing that bunching-together effect.

I assume that you have already (or will have) dragged a purely mechanical rake, to eliminate branches and other such stuff that might damage your material. This will preclude damage to the conduits/wiring of the nail-eradicator.

Having multiple V-shaped plows dragging your energized magnets thru the mud will assure attracting and holding even those nails that might be in the worst possible orientation: head-down, point "Up", and just beneath the surface.

Wish you the best with this ~

Tom,

I find humor in everything. It keeps me from having a too serious attitude about life and that is always fatal.

this array is similar (I think) to some form of plowing mechanisms i saw for field work.

The magnetized chain and wire wrapped coils are one way this can work and the magnet array is certainly another. I think the two togther wil cover all the area we need to cover.

Thank you for the idea and thank you for getting my 'ducks' in a row.

Smitty

Always enjoy the simpler things ...! 'Specially them what gots options...

If you get tired of winding magnet-wire, you can always resort to epoxying a bunch of THESE to some flexible hinged arrays... Have fun with it...(!)

You wouldn't by chance be tweaking some crawfish ponds here in "south Louisy", would you?

~

The trouble with those is you can't turn them off to release the collected material.

I like your Geese idea. It is probably possible to find a bunch of electromagnets already wound, that could be attached to some triangular plates in that fashion, although finding ones suitable for underwater use might be more difficult..

Dick

Crawfish ponds are all dried up and getting ready for another year of rice production.

Folks still plant rice to feed the crawfish on the stubble.

When those big @$$ Allis Chalmers get finished laser leveling ......any nails or junk would be long buried.......

I'll let you all know what happens. It looks like a combination of both of these devices.

radio speakers would be an excellent source for magnets and wire.....I know just where a stock of old broken ones are.............

Thank everyone.

Smitty

I am impressed with how well these two people have worked out a solution for you.At this point The only suggestion I can offer is used speakers. They have copper wire wound in a small spool with both ends exposed. Try to examine a few speakers of varying wattage. When the wire looks like what you want, contact a few radio installation shops for their junk speakers. Check them with an ohm meter to test I would bet that these two posters already know what wattage speakers you will need to get the wire you need. Good luck, and let us know how it works.

Hi Bob!

Unfortunately, the voice coils of speakers are only intended to move in the field of their permanent magnet (unless it is a REALLY old speaker with an electromagnet), and they are rarely waterproof.

I was thinking more on the line of

70155K57
(Same as 70155K2)
Linear Solenoid Continuous, Pull, 12 VDC, 0.5" Stroke, 12 oz Force

In stock at $8.82 Each

from McMaster-Carr.

These are already made for 12V, so all of them would be wired in parallel. They would require some modification for this purpose, but it would be much faster than winding coils from scratch. Once again, they could be potted in epoxy to make them waterproof.

I remember pulling speakers apart and there was coiled thin copper wire in them. I also remember being a little boy. Neither were not recent.

There are air and hydraulic valves that use a solenoid to activate them. These valves use a removable coil to adjust the valve operation to match the power supply. The ones i see commonly are 12 and 24 volt dc, 120 and 240 volt ac and some others that i never paid much attention to. I have seen them from ARO, Red Hat, And a few others. the coils are 1-1.25" tall 1" wide with a 1/2" hole in the middle. Already sealed in epoxy. I will try to get a part # and picture.

"Neither were not recent." ???

I believe I took my first speaker apart in '44 or '45, when my dad worked at Magnavox. I still have a few alnico magnets around. The wire from those speakers was way too small, like #50 or #60, and not enough of it. For this job we need something in the range of 100-1000 turns of wire for each coil, and for 12 V operation, I think closer to the bottom end of that range, with at least #25, and probably bigger size.

"Neither were not recent." ???

Sorry.

Would higher wattage speakers use heavier wire.

Of course, but still a single layer. Some of the larger speakers use flat wire wound on edge, to get more turns in the smallest possible gap.

Some of the really old speakers used electromagnets instead of permanent magnets. Now those coils had LOTS of wire, but it was pretty small. Commonly that electromagnet also acted as a filter inductor for the plate power supply of around 300 Volts.

The above coil is 12 volt dc, and has a list price of 18.60 from Grainger. Part # is-

4kp76

Once again, thank you all for the input. there is a Graingers within driving distance.

smitty