# non-ferrous magnetism



## EVO-AU (Jan 21, 2009)

Any takers on this one ? ( And don't tell me it doesn't work, because I've seen it in action. )

Anybody have any experience on this juicy bone ?

Phill


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## Anonymous (Jan 21, 2009)

Is this what you had in mind.


rexresearch.com

MASTER MAGNET

This electromagnet attracts non-ferrous metal objects by AC induction!

The Magnet’s Secret:

Since the electromagnet’s windings are powered by AC, an alternately increasing and decreasing magnetic field is set up in its center core. When this varying field passes through a set of copper washers fastened to the end of the core, a large current is induced in them. The washers, then, act essentially as a transformer secondary.

The induced current sets up a strong, varying magnetic field in the washers. And the direction of this field is such that the washers and the core repel each other. If the washers were not anchored in place, they would spring out of their mounting as soon as the current was turned on.

The point is, though, that the varying field in the washers will induce, in turn, a large current in any metal object (ferrous or not) brought near them. This current, of course, sets up a magnetic field in the object. And the direction of the field will always be such that the part of the object in contact with the outside face of the set of washers will move the opposite magnetic polarity fro that face. Therefore, the object will be attracted.

Building Magnet Cores:

To start, first cut a 3-1/2" section from a 2" diameter mailing tube. Make a frame for the inner core of the magnet as described in Detail "A". In forming the frame the three wooden discs should fit snug inside the tube. The four ¼" diameter wooden dowels will pass through the discs by holes drilled then glued in to place to hold the assembly together. The core material will later fill the ¾" diameter hole drilled into the centers of the discs.

Now slide the frame into the mailing tube spaced ½" from one end and flush on the other end and glue in this position. Three copper washers will fill the ½" space later on (See Detail B Side View).

Set the closed end of the tube down on a table top and proceed to pack the core with lamination approximately ¼" wide and 3-1/2" long. Laminations may be removed from an old transformer or made from 18 to 22 gauge soft iron wire cut squarely on one end 3-1/2" long. The pieces should make a smooth surface when packed together.

Next, slide a 3-1/2" long, 3" diameter mailing tube over the completed assembly centered as near as possible. Fill the space radially around the inner core assembly with laminations like previously used wide enough to fit snug and 3-1/2" long (See Detail B End View)

Winding the Coil:

For this step you need a jig similar to the one in Detail C. This wooden cylinder with two fitted end-pieces is 3-1/2" long and 1/16" larger in diameter than the mailing tube’s diameter. The end pieces are sawed so that slots are formed to allow temporary tie wires (see next paragraph), and a metal crank handle runs through the center of the cylinder.

The jig is now ready. Center 12" pieces of hookup wire in each slot, pressing them flat. The coil will be wound over this and the wires will serve to temporarily hold the coil together when removed from the jig. Next, frill a hole in a block of wood clamped in a vice. This will hold the jig as you crank the other end.

The coil is made up of 600 turns of #14 cotton or enamel-covered magnet wire tapped at the 350th turn. Around 9 pounds will be needed. Insert the rod end of your jig into the block of wood, stick the first 6" if the end of your supply wire through a saw-slot, then start winding the wire in layers onto the cylinder.

When the 350th turn is reached, tap on a 6" length of wire and brig it out through a saw-slot. The point of tapping can be varied as much as 10 turns in either direction so that the tap out is at the end of a layer on the same end a s when we started the coil. Now continue until the 600th turn is completed and bring the end of the wire out the same end through a saw-slot and cut leaving a 6" piece as before.

Final Assembly:

Using the wires previously inserted, tie the windings together. Disassemble the jig and remove the coil. Using ½" wide cotton or linen tape, wrap the coil from the inside to the outside in overlapping layers. Once completed, coat the inside of the coils and the outside of the 3" mailing tube assembly with glue. Make sure the leads and the space for the copper washers are on opposite ends, insert the cores into the coil, and allow the glue to dry.

During the drying time make a ½" thick wooden ring with the inside diameter [?] wide and the outside diameter flush with the outside of the coil. This is a spacer between the coil and the top (See Detail B Side View). Cut grooves in the spacer to allow the leads to pass through the center and glue onto the coil.

Now with the same outside diameter as the spacer, cut a ½" wooden top. Mount a lifting ring in the center, made from brass or copper. Drill another hole for a 6’ length of #14 stranded, 3-wire conductor for the power cable. Push one end through the hole and connect the coil leads to the cable leads.

At the free end of the power cord mark each of the leads as connected with "start of winding", "tap", "end of winding". This is important for later hook up. Next glue the cable in its hole so connections cannot be pulled apart by flexing. The wooden top can be secured to the spacer ring by brass wood screws. Next coat the whole magnet with black insulating varnish or enamel to help secure the cotton or linen coil wrappings and protect it from moisture.

The last part of construction is the forming and installation of copper washers in the space between the ends of the inner and outer magnet cores. Specifications of the washers are in Detail D.

These copper washers are secured with flathead brass wood screws driven into the inner core. Counter sink the screws into the outside washer, and fill any excess space between the washers and the inner coil with slices of wood or cardboard so the last washer is flush with the inner and outer cores.

Do not substitute any other metal in place of the copper washers. Heavy current induced by the washers require that they be made of extremely low resistance metal.

Electrical Hookup:

If the AC line is connected between terminals 1 and 2 of the magnet coil (See Schematic A), the current consumed will be around 20 amperes --- quite excessive for use around the house. Connecting terminals 1 and 3 (See Schematic B) results in a current flowing around 4.25 amperes, and the strength of the magnet is reduced proportionately. In both cases the current performs little useful work; this inductive circuit lags about 90* behind the voltage.

This lag can be partially offset by adding an 80-uf, phase-shifting capacitance as shown in the modified parallel-resonant circuit of Schematic C. The current drawn from the line is about 4 amperes, while the currents flowing between terminals 1 and 2 and terminals 3 and 4, respectively, are 18.5 amperes and 9 amperes. This hookup results in a more powerful magnet than the hookups in Schematics A or B.

The maximum magnetic pull is obtained with the series-resonant circuit illustrated in Schematic D. In this hookup, 17 amperes flow through the whole coil, allowing the coil to pick up and hold 6 or more half-dollar coins or an equal weight f other non-ferrous metal.

The 80-uf capacitance specified in Schematics C and D is built up by paralleling several smaller capacitors. These must be of the non-electrolytic type with ratings of at least 250 volts if connected as in Schematic C, or 600 volts if connected as in Schematic D. Units totaling less than 80-uf could be used, providing they have the proper voltage ratings, but the current flowing through the magnet winding would be reduced.

High voltage appears across the capacitors, and since they are apt to retain their charge after being disconnected from the line, this should be enclosed in a metal box. As another precaution, the capacitors should always be discharged with a tool having an insulated handle before any work is done on the circuit.

Because of the peculiarities of the magnetic field around the copper washers, the magnet will not attract pieces of non-ferrous metal wider than their outside diameter or nattower than their inside diameter.

A final word of caution: the washers carry considerable current through them and get quite hot. Connect the magnets only when necessary.

Materials:

1 Cardboard mailing tube, 3-1/2" long, approx. 2" diameter
1 Cardboard mailing tube, 3-1/2" long, approx. 3" diam.
4 Wooden dowels, 3-1/2" long, ¼" diam.
1 Roll ½" wide cotton or linen tape
1 Heavy brass or copper hook (for lifting ring)
1 Line plug
1 80 uf, 250 or 600 volt capacitor bank
1 Wood or metal enclosure for above
1 6’ length of #14 stranded 3-wire cable (for power cord)
1 6’ length of #14 stranded 2-wire cable (for line cord)
9 pounds of #14 cotton or enamel covered magnet wire
Miscellaneous:
½" wood stock for center core frame, magnet top and spacer ring
1/16" sheet copper for washers
Old transformer lamination or 18 to 22 gauge soft iron wire for cores
Parts for winding jig
Flat head brass wood screws
Cement
Insulating varnish or enamel

Schematics A, B, C, D:
Terminal 1 = Start of Winding
Terminal 2 = Tap
Terminal 3 = End of winding

Detail A:

Detail B:

Detail C:

Detail D:


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## EVO-AU (Jan 22, 2009)

Gustavus: All of your material is right on the head, except that I got mine from an article in a 1960's Popular Mecahnics. I just finished building mine and 30 amps is where I am at. Interesting little project.

By the way, you state in your research that 20 amp circuitry is hot for a residence. Actually, except for some lighting runs, clothes dryer, range and hot water 20-amp circuitry is the norm. Unless, like some backyard contractors Al wire is used, than the wire must be one size larger to accommadate the same amperage.

Have you built one yet ? ( By the way, is Birnie in Scotland ? )

Evo

Almost forgot - this little beauty was built almost 100 years ago in a physics lab.


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## EVO-AU (Jan 27, 2009)

Gustavus: Are you going to build one of these and experiment ?

Anybody else got anything to add ? Sure would like some other thoughts on this metter .

EVO


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## Platdigger (Jan 27, 2009)

Hi Phill, ever see were this shaker tables uses magnets in a different way?

The RP-4 uses a unique reverse polarity of rare earth magnets which will cause the magnetite to rise and be washed off into the tails leaving just the gold traveling to the catch.

Like to know how this works........

Have you tried out the magnet you built?
Randy


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## Anonymous (Jan 28, 2009)

EVO-AU said:


> Gustavus: Are you going to build one of these and experiment ?
> 
> Anybody else got anything to add ? Sure would like some other thoughts on this metter .
> 
> EVO


No I'm not building one, just thought it an interesting question and googled it. The credits belong to someone else - not I.

In answer to your question I would have answered platinum as being slightly magnetic as are certain types of stainless steel.


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## EVO-AU (Jan 29, 2009)

Randy: Well, so far I have burned out two rheostats andf almost my fingers. Afterall these years around electricity, I still manage to get careless. Or is that word spelled cocky ? I'm thinking of bulding a water rheostat, but I haven't the foggiest where to start. Boy, this net is great - I just found s bunch of articles on how to build one ...

Gustavus : I was prowling around a scrap metal place awhile back, ( looking for stainless pieces for my cell ) and found some pieces of stainless non-magnetic. I was surprised. 

I know nothing about Pl - except that is is richer than gold. You will have to ask Platdigger about that, as he is the expert on Pl.

Phill


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## Harold_V (Jan 29, 2009)

EVO-AU said:


> and found some pieces of stainless non-magnetic. I was surprised.


You shouldn't be. All of the 300 series of stainless is non-magnetic, and that's the stuff you see commonly. Steam table pots are an example, as would be stainless hoods and counters found in industry. 

The exception to 300 being non-magnetic is if it is work hardened, at which time it is mildly magnetic. 

Harold


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## Anonymous (Jan 29, 2009)

EVO-AU said:


> Randy:
> 
> Gustavus : I was prowling around a scrap metal place awhile back, ( looking for stainless pieces for my cell ) and found some pieces of stainless non-magnetic. I was surprised.
> 
> Phill


I hope you purchased the non magnetic stainless for your cell, would have been my choice.


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## EVO-AU (Jan 30, 2009)

Harold/Gustavus:

That was going to be my next question. Non or mag ? I haven't purchased yet; I have this bad habit of looking at everything and wondering - now - what can I use this for ? Or hey, I think this is something that I need for a project that is half there, but ran short of available whatever it was that I needed at the time. Boy, do I like to prowl junkyards. No telling what is under the next piece of whatever ?

Thanks, guys. Phill

Gus - I read about that somewhere and it does make sense. Thanks


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## Harold_V (Jan 31, 2009)

Make your choice non-magnetic, and if you get lucky and can identify the material, your best choice is 316 L. It's unlikely you'll know what it is, however. 304 or 316 are commonly used for making containers for transporting nitric acid. 

Harold


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## Platdigger (Jan 31, 2009)

All the 316 I ran into......at least that I believed to be 316, was slightly magnetic. 
It is one way I seperated stainless scrap. Of course there is the grinder test, and to be real sure the chemical test for molly.
Randy


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## Harold_V (Jan 31, 2009)

I trust you find it only very slightly magnetic? If so, and it becomes non-magnetic upon being heated to redness. it's a sign of being rolled, but not annealed (work hardened). Otherwise it's a good sign it's not stainless. That's true of all of the 300 series materials. 

The 300 series of stainless does not have the ability to be heat treated for hardness----it hardens by work hardening alone. 

Harold


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## Oz (Jan 31, 2009)

Off topic a bit but how does carbon content enter into this with 300 series stainless or is there some other reason it will not heat treat. I have done little work in stainless at the forge but having said that I think you see why I’m asking.


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## Platdigger (Jan 31, 2009)

I have sold quite a lot of stainless Harold. And as I recall all of what tested out at the scrapyard or was marked 316, was slightly magnetic. 304 generally is not. 

If you have something that is stronly magnetic but looks like stainless it probably is one of the 400 series of stainless. Some of this has chrome but no nickel.

Or if you are fortunate, it could be monel, Inconel or one of the other high nickel, high temp varieties.
I have encountered these too, the payout can be nice on these if nickel happens to be high at the time.
Randy


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## Oz (Jan 31, 2009)

Plat,

I had a conversation with a gentleman a few weeks ago that used to work in a steel mill and he mentioned that monel or inconel contained platinum group metals (i don't remember which) to give it the high temp resistance. I am not presenting this as fact but only something that makes limited sense in that some platinum group metals would increase temperature resistance like in jet engine parts. But I don’t know the guy and for all I know he is a crazy as a loon.


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## Platdigger (Jan 31, 2009)

I know there are some inconels that contain either niobium or tantalum,
but I don't know of any that contain any of the pgms Oz
Not saying there are not any, I just don't know of them if there are.

Yea, jet engine parts.......but I am not sure what those alloys are called.
Chris should know.
Randy


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## Oz (Jan 31, 2009)

Sure enough, Chris would as he has refined a good deal of jet engine parts. Maybe we will get a verdict.


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## qst42know (Jan 31, 2009)

You can wiki the Monel and Inconel. 

There are no PMs in the alloys themselves but fabrication of components may include brazing alloys that do.

Here is a chart of the alloys.

http://www.painc.com/chemical_composition.htm


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## Harold_V (Jan 31, 2009)

Oz said:


> Off topic a bit but how does carbon content enter into this with 300 series stainless or is there some other reason it will not heat treat. I have done little work in stainless at the forge but having said that I think you see why I’m asking.


The carbon content in all 300 series stainless is well below limits that would permit heat treat by the carbon cycle. In a worst case scenario, as an example, 316 would contains less than half the amount of carbon that is found in 1018 steel, which is a low carbon steel and can not be heat treated by common heat treat methods due to the minimal carbon content. 

316L has an even lower carbon content, which is intended to reduce harmful precipitations when the material is taken through 800°-1,500°, such as when it is welded. The precipitation in the heat effected zone is the source of intergranular corrosion. 

Harold


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## Harold_V (Jan 31, 2009)

Platdigger said:


> I have sold quite a lot of stainless Harold. And as I recall all of what tested out at the scrapyard or was marked 316, was slightly magnetic. 304 generally is not.


That is not a method of determining grade, for both of those materials are slightly magnetic in the work hardened condition, and both are not when annealed. The same thing applies to all of the 300 series, so they can not be sorted by their magnetic properties. However, you can sort the 300 series in the annealed condition from all other grades, for they are magnetic in all states. 

This information is provided in (material) stock books and is readily available for those that deal with such materials. It is common knowledge amongst machinists. 

I'm not suggesting that you didn't sort by the method, but I am saying that it is not reliable, so you well could have been passing 304 for 316. They are identical in appearance and other properties. They are difficult, if not impossible, to sort by machining, while some grades are not. For example, one can discern 303 S from 303 Se, and all 303 types are readily sorted from all other 300 series by a simple cut with a lathe. That's assuming you are familiar with the properties of the materials, which I am. 



> If you have something that is strongly magnetic but looks like stainless it probably is one of the 400 series of stainless. Some of this has chrome but no nickel.


That isn't reliable, either. 17-4 PH and 17-7 PH are both magnetic, and are not in the 400 series. You may be able to include 13-8 and 15-5 with those two, but I hesitate to say with certainty because I am not familiar with the properties of those two. I do know that they all contain both nickel and chromium, but in varying amounts. 

These materials are all precipitation hardening, and do not rely on carbon content to achieve their hardness. 

Harold


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## goldsilverpro (Jan 31, 2009)

I found quite a few lists of the chemical composition of superalloys on the internet and could find none containing PGMs. Here is a fairly complete list.

http://www.dynamicmet.com/sp4.htm


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## jimdoc (Jan 31, 2009)

There was talk of using ruthenium and rhenium in super alloys.

http://www.lipmann.co.uk/articles/will_aero_engine_makers.html


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## goldsilverpro (Jan 31, 2009)

I stand corrected. I just found this quote:

"The superalloys of the first generation were intended for operation up to 700 °C (973 K). The up-to-date superalloys of the fourth generation are used as single crystals and are extra alloyed, especially with ruthenium. They can operate up to 1100 °C (1373 K)."

And:

http://www.google.com/search?q=ruthenium+superalloys&sourceid=navclient-ff&ie=UTF-8&rlz=1B3GGGL_enUS259US259

http://www.google.com/search?q=rhenium+superalloys&sourceid=navclient-ff&ie=UTF-8&rlz=1B3GGGL_enUS259US259


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## qst42know (Jan 31, 2009)

Assuming one could find this exotic alloy containing approximately 5% to 10% Ruthenium, by what method would the recovery of this metal from a nickel chromium base be possible for a small scale refiner?


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## Platdigger (Jan 31, 2009)

If you go back to my post Harold, I didn't say it was 400 only.

I think you took ....I mean, in a way, you pulled a quote out of context.

As far as I know, all the 304 I ran into was non magnetic.

I am sure there could be exceptions to that also.

If it was slightly magnetic.....or even somewhat strong and not marked, then I had it tested.

It could also be our use of the word "slightly" could be different.

Are you saying there is 316 that is non magnetic?
Randy


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## Harold_V (Feb 1, 2009)

Platdigger said:


> If you go back to my post Harold, I didn't say it was 400 only.


I just wanted to assure readers that being magnetic is not a sign of stainless being a 400 series. You said: 


> If you have something that is strongly magnetic but looks like stainless it probably is one of the 400 series of stainless.


That stainless is magnetic is no more an assurance of it being a 400 series than one being slightly magnetic being 316. That is not the case in either example. The point is that stainless alloys are incredibly complex and tend to not fall in categories. Not all of them that are not magnetic can't be heat treated, so even that feature isn't acceptable for grading. An example of a non-magnetic stainless that can be heat treated is A-286. To the uneducated, it could easily be confused with a 300 series stainless. 



> I think you took ....I mean, in a way, you pulled a quote out of context.


I don't think so. I simply read what you said and knew that it was not true _in all cases_. I think readers should understand that there are differences, that you can't generalize. As I said, unless you know and understand the stainless family exceedingly well, there are exceptions to almost all of the rules, so you can inadvertently provide misleading information. 



> As far as I know, all the 304 I ran into was non magnetic.


Any of the 300 series materials will acquire minimal magnetic properties as they are cold worked. I mentioned that previously----it's called work hardening. Not only does the item become mildly magnetic, it also becomes harder. It's to do with alignment of the atoms of the material. It's not speculation-----as I said, this is published information. A ready reference is the Jorgensen Stock Book, which details the magnetic properties of these alloys. 



> Are you saying there is 316 that is non magnetic?


No, I'm not saying it----the stock book is. It is published information, coming from a source that is an accepted authority in the machining world. _*All*_ 316 is non magnetic. Only when it has been cold worked does it assume magnetic properties, with the degree of magnetic attraction related to the degree of cold working. It becomes mildly magnetic, never achieving the same degree of magnetic attraction as do other materials we accept as being magnetic. 

As I said, you can not determine if a material is any given grade judging by magnetic properties. You can't even assume a stainless alloy is a 300 series if it is NOT magnetic-----there are exceptions to that, too. Again, I offer you as an example, A286. It is not magnetic under any condition, yet it can be heat treated. That tends to go against everything you know and understand about heat treatment of stainless, but, remember, I already mentioned the fact that carbon is generally not the reason these alloys heat treat. 

A286, like 17-4 PH, 17-7 PH, 13-8 and 15-5 are all precipitation hardening materials. Some are magnetic, some are not. 

Harold


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## EVO-AU (Feb 2, 2009)

To one and all:

Boy, did I ever open up a pandoras' box. Ask a man if a traffic light is red or green and he will, most assuredly, state the orange is what counts. Oh well, I doubt if I will ever come across any of the sophisticated alloys of which you gentlemen speak, but thanks for all your work. 

Phill


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## Anonymous (Aug 4, 2010)

Try taking some "slighty magnetic" SS to the scrap yard and selling it as stainless. Talk about a pandora's box... And I am not talking about something that is chromed either...


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