# Since when is brass magnetic?



## Inferno (Dec 20, 2020)

I bought a few slugs of 2"X5" brass round for a small, fun, project. I was creating a "magic trick" for my grandson where you drop a ball bearing through a cylinder and it passes right through but a magnet will have a wake that slows it down. 
I made one from aluminum a while ago but thought brass would be prettier. 

It took me 4 hours to finally get a 1-3/8" hole through the brass round. I was using a 1-1/4" sphere N52 NdFeB magnet. 

I was pretty excited to try it out. I dropped the magnet into the bore and it never came out. It was, notably, stuck to the wall of the bore. 
I checked it out more after retrieving the magnet and, sure enough, the brass was magnetic. 

I checked 3 other pieces I picked up from the same salvage yard and two of them were magnetic. One wasn't. 

What's the deal here?


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## benmychree (Dec 20, 2020)

I wonder if the "brass" was aluminum bronze, makes sense that it would take that long to drill it out, it is tough stuff!  I think I remember that it is slightly magnetic.


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## Inferno (Dec 20, 2020)

benmychree said:


> I wonder if the "brass" was aluminum bronze, makes sense that it would take that long to drill it out, it is tough stuff!  I think I remember that it is slightly magnetic.


I wouldn't say it was tough. It just expanded a lot. My bigger bits would only drill about a half inch or so deep before they started to bind. I had to keep step drilling every half to 3/4 inch


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## benmychree (Dec 20, 2020)

Aluminum bronze does that; back in my apprenticeship I saw a Croatian journeyman using a carbide bit with ground in chip breaker cutting what looked like brass, and I askes him about it; his answer was "thees ees nota brass, it ees yellow steel"


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## JimDawson (Dec 20, 2020)

Copper pipe works really well for that.


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## brino (Dec 20, 2020)

Yes, a Lenz's law demonstration!

I have done that myself.
I had brass, aluminum, copper, and stainless steel tubes for comparison........and some clear plastic tube to show "no affect".
The (100 or so!) kids had fun dropping magnets thru the tubes and seeing the difference.
They'd hold two tubes and "walk" the magnet thru them alternately.
Great fun learning!

I had to go thru a couple stainless tubes to find one that was not magnetic....some alloys are, some are not.

I suspect your "brass" was some steel-bearing alloy.

-brino


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## Inferno (Dec 20, 2020)

Never heard of aluminum bronze. Based on the shapes of the other crap pieces I ended up with, it makes sense.
I never imagined that adding aluminum to copper would make it magnetic.

Of course it could still be something else entirely I guess.

For the Lenz Law devices. Yes, I know about the copper tube and other ones you can buy. I was hoping to make them for my grandson as something he could go through life with, saying "My grandpa made this".
I will still make the aluminum one. I KNOW that's not magnetic.

From now forward I guess I'll take a magnet with me when shopping the scrap bins.

It sounds like this should be strong enough to make a signal cannon from. Not the first piece, of course. I have a couple more that are, for me, otherwise useless.

*Side note: N52 NdFeB, 1.25" spherical magnets are NOT a toy. I did my best to not let them snap together but they did. If they had been any other shape, it would have taken away skin. Now I can't get them apart with my bare hands. *


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## reds (Dec 20, 2020)

I have run across quite a few brass wood screws  lately, that were magnetic ...Have to wonder if China manufactures a mystery metal and passes it off as brass.


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## eugene13 (Dec 20, 2020)

Lenz's law,  a practical use of which is variable speed or soft start couplings, I watched  demonstration where I used to work. Amazing


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## Inferno (Dec 20, 2020)

eugene13 said:


> Lenz's law,  a practical use of which is variable speed or soft start couplings, I watched  demonstration where I used to work. Amazing


I have a machine at work that has a spool of, basically, flat steel on it. The machine pulls the steel each cycle. 
Sometimes the spool would jerk hard enough to spin the spool and the steel ribbon would droop too much and then jam the machine. 
The mechanics solution was to wedge a piece of rubber foam between the spool wheel and the frame. My solution will be to add a metal plate to the spool and a very strong magnet to the frame. Essentially a magnetic, free wheel, speed controller.


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## mksj (Dec 20, 2020)

I had a similar issue with a mill tachometer where the sender was embedded in an aluminum outer ring and the magnet on an inner ring with a 0.1" gap, worked fine on the bench but gave weak readings when installed on the mill. Only thing I could figure is that the magnet spinning around the ring holding the sender would induce a magnetic field that would effect the senders ability to pick up the magnetic pulses. Was news to me when I looked into it,  Lenz  effect. Must be funny brass...


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## RJSakowski (Dec 20, 2020)

reds said:


> I have run across quite a few brass wood screws  lately, that were magnetic ...Have to wonder if China manufactures a mystery metal and passes it off as brass.


Brass plated hardware is common and has been for 100+ years.  In this case,it was a piece of 2" round that was bored with a 1-3/8" hole.


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## Lo-Fi (Dec 20, 2020)

Nickel is magnetic and it's compounds often have a yellow tinge. It's also quite cheap...


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## Inferno (Dec 20, 2020)

Pretty sure it's not Nickel


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## homebrewed (Dec 20, 2020)

mksj said:


> I had a similar issue with a mill tachometer where the sender was embedded in an aluminum outer ring and the magnet on an inner ring with a 0.1" gap, worked fine on the bench but gave weak readings when installed on the mill. Only thing I could figure is that the magnet spinning around the ring holding the sender would induce a magnetic field that would effect the senders ability to pick up the magnetic pulses. Was news to me when I looked into it,  Lenz  effect. Must be funny brass...



The eddy current induced by a moving magnet produces its own magnetic field that opposes the external magnetic field.  It's nature's way of saying "get outa here!".  So it's not surprising that the embedded sensor is not seeing the full strength of the magnet.  If you still have the setup around, an easy demonstration of this effect would be to very slowly move the magnet over the sensor, because the effect depends on the speed of the magnet -- faster = stronger eddy currents, therefore greater reduction of the field detected by the sensor.


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## jcmullis2 (Dec 21, 2020)

I read something recently about some of the “brass” having a slightly different makeup and of course it’s lower grade stuff for a lack of proper terms. It’s technically brass but not the stuff we’re familiar with. I bet you paid full brass price for your yellow metal. At least the brass grinder wheels like that are inexpensive


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## Peyton Price 17 (Dec 21, 2020)

Inferno said:


> Pretty sure it's not Nickel
> 
> View attachment 348076


i made a bushing from brass that looked like that and was magnetic and clogged up a drill bit too.


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## Lo-Fi (Dec 21, 2020)

Won't be pure nickel, but wouldn't put it past some being thrown in because it's cheap...


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## addertooth (Dec 21, 2020)

If you really want to demonstrate Lenz's law, use a formed and rolled sheet of "pyrolytic Graphite" glued to the inside of a plexiglass tube.  It is a more dramatic effect than even the best grade copper.


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## RJSakowski (Dec 21, 2020)

jcmullis2 said:


> I read something recently about some of the “brass” having a slightly different makeup and of course it’s lower grade stuff for a lack of proper terms. It’s technically brass but not the stuff we’re familiar with. I bet you paid full brass price for your yellow metal. At least the brass grinder wheels like that are inexpensive


Brass is generically an alloy of copper and zinc but there are dozens, if not hundreds, of  different compositions with different minor alloying metals.  Some of the "cheaper" brass was the result of outlawing the use of lead in articles use for potable water .  The resulting alloy is highly susceptible to erosion from acid water resulting in a porous structure. A plumbing fitting that I installed 7 years ago has been leaking for the lat four years.  I have the replacement fitting but it is a major task to replace it and the leak goes into a basement drain.  Besides, I have no reason to suspect that the new fitting will last any longer so I put up with the annoyance.  

I deid some searching to se if iron was an alloying metal for any brass but failed to find one where there was a significant percentage.


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## rwm (Dec 21, 2020)

Just for kicks I went thru my brass scrap bin. I cannot find any that is even slightly magnetic. You must have an alloy with a magnetic contaminant in there. Aluminum bronze can have up to 6% iron so that is a good guess.
Robert


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## homebrewed (Dec 21, 2020)

rwm said:


> Just for kicks I went thru my brass scrap bin. I cannot find any that is even slightly magnetic. You must have an alloy with a magnetic contaminant in there. Aluminum bronze can have up to 6% iron so that is a good guess.
> Robert


Agree.


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## John_Dennis (Dec 21, 2020)

reds said:


> I have run across quite a few brass wood screws  lately, that were magnetic ...Have to wonder if China manufactures a mystery metal and passes it off as brass.


Magnetic "brass" screws are just plated steel.


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## jcmullis2 (Dec 21, 2020)

RJSakowski said:


> Brass is generically an alloy of copper and zinc but there are dozens, if not hundreds, of  different compositions with different minor alloying metals.  Some of the "cheaper" brass was the result of outlawing the use of lead in articles use for potable water .  The resulting alloy is highly susceptible to erosion from acid water resulting in a porous structure. A plumbing fitting that I installed 7 years ago has been leaking for the lat four years.  I have the replacement fitting but it is a major task to replace it and the leak goes into a basement drain.  Besides, I have no reason to suspect that the new fitting will last any longer so I put up with the annoyance.
> 
> I deid some searching to se if iron was an alloying metal for any brass but failed to find one where there was a significant percentage.


I’m no metallurgist but the metals produced today must be made to different standards than the metals we’re accustomed to. The answer to how they are able to call this mystery metal brass is probably in a government manual. I’m sure some agency decides exactly what composition of alloys or whatever are allowed to be called brass.


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## rwm (Dec 22, 2020)

Bronze and brass are somewhat loosely defined...In most parlance brass is a copper alloy that has Zn as the principle alloy ingredient. Really cheap yellow brass gets up to 35% Zn. Bronze is a copper alloy that has...anything else...most commonly tin. Aluminum bronze is copper and aluminum and is used primarily for marine applications. There are exhaustive tables laying out the compositions of multiple alloys. ASTM decides on the specifications for alloys in the US. Iron is allowed in some concentration in many alloys, hence magnetic. I have made a bunch of 85 triple 5 brass which I love the color of. This is 85% copper, 5% each of Zn, Sn, Pb. Funny thing about making brass is the Zn is always boiling off so you have to guess at the final composition! Just throw a few pennies (Zn) in at the end maybe. The addition of Zn or Sn to Cu significantly lowers the melting point and makes the material much more accommodating to casting.
Robert


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## Inferno (Dec 22, 2020)

I'd kind of like to know what the stuff really is but not to the point of wasting any money to find out. 
It sounds like, no matter what it is, it's not some exotic metal left by aliens.


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## brino (Dec 23, 2020)

Inferno said:


> It sounds like, no matter what it is, it's not some exotic metal left by aliens.



Nope.......but if you find any transparent aluminum, please let us know! 
-brino


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## Steve Shannon (Dec 23, 2020)

Is Brass Magnetic? What Is Magnetic Brass?
					

The short and skinny answer? No, brass is non-magnetic. But, there are some very real circumstances that cause genuine brass to be noticeably magnetic. It is not actually the brass that is magnetic…



					www.scrapmetaljunkie.com
				




Merry Christmas everybody!


Sent from my iPad using Tapatalk


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## Weldingrod1 (Dec 23, 2020)

That stuff is Nickle Aluminum bronze. Serious good-stuffium! Really strong, doesnt gall with most metals, but a tad magnetic from the nickle content. Aluminum forms aluminides with iron and nickle; crazy hard and brittle. Not sure what othe metals... I once screwed up a casting by thinking "oh, yeah, Aluminum bronze is great stuff!" And dumping some ally into the mix. End result was very hard and brittle as glass. Broke one just getting it out of the sand!

Regular brass can have a tiny bit of Iron contamination, but I think the limits are low enough that even neo magnets wont stick.

Sent from my SM-G892A using Tapatalk


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## jcmullis2 (Dec 24, 2020)

That sounds like it might cost more than brass.


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## Inferno (Dec 24, 2020)

What is "gall"
I haven't heard that term.

I thought my drill bits were dull so I purchased a new final cut 1-3/8" bit. It finally came today. 
Knowing that this brass wasn't the right stuff, I'm sure my other bit was probably OK. It did seem to chatter a lot so maybe it wasn't ground even. 
I'll use the new bit when I make the new cylinder(s) from aluminum. 
I figure as long as the brass is already hollowed out I can use it to create decorative rings for the final aluminum ones.


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## jcmullis2 (Dec 24, 2020)

Inferno said:


> What is "gall"
> I haven't heard that term.
> 
> I thought my drill bits were dull so I purchased a new final cut 1-3/8" bit. It finally came today.
> ...


It probably ruined your drill bits but hopefully you only used a few on that stuff


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## Jim F (Dec 24, 2020)

Inferno said:


> What is "gall"
> I haven't heard that term.
> 
> I thought my drill bits were dull so I purchased a new final cut 1-3/8" bit. It finally came today.
> ...


"galling" is basically cold welding.


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## Inferno (Dec 24, 2020)

jcmullis2 said:


> It probably ruined your drill bits but hopefully you only used a few on that stuff


I used 7 different bits on the stuff. I won't know til later if I ruined them or not. For anything under 3/4 I have spares. Over that, well, how often do you drill 7/8 and up?


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