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  1. #21
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    Wonder if suspended ferritic material in the coolant is coating the chips?
    Like a floculant in water plants
    Perhaps the coolant needs a magnetic filter like we have on heating boilers over here, amazing how much black goo comes out of the heating from the steel radiators
    Mark

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  3. #22
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    I don't believe in iron from coolant making chips magnetic enough to have any significant effect

    I do believe in magnetic induction of the same al chips when magnet is moved around near them, I think everyone is aware of induction motors with "aluminum" rotors

    you have numerous coils basically in that pile of shavings and moving a strong magnet around them will most definitely have some sort of reaction, nothing like iron of course, but they won't be inert, and that is what those con artists are using to fool people

    and of course they'll act all surprised and dumb when confronted about it, or hostile

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    Well I am grateful for all the responses . I did actually see the magnet stick to the outside of the plastic bag they were in . Back when I was doing a lot of SS , they would be able to judge if it was slightly magnetic and adjust to the next lower price .
    I did get $2 for the bag of cans I had . treated myself to a cup of coffee .
    Really not worth the effort to collect and take in chips nowadays . I guess I will have to compact them and throw in the trash a bit at a time .
    Since I am the flatbelt guy , I do want to share a tip I got from a local Amish guy :
    asked where can I get the old school tube of stickum to dress flat leather belts . Not made anymore , but he says go to the drug store and get a can of CASTOR OIL . Not cheap , $7.00 for a 4oz plastic bottle . Thick as honey , so I drilled a 1/4" hole in the top and pushed a pc of copper tube in as a spout .
    "Holy Cow" ( as we say in the midwest ) this is really amazing stuff and you can hear the belt sticking immediatly . I might have to check ebay for a larger bottle

  6. #24
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    And I paid £8 for an aerosol of belt dressing, who’d think, plus handy for constipation I’m told
    Mark

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    Most scrap yards cheat, guy probably had steel dust in his front pocket, the one he pulled the magnet out of...I do sell brass and a use a big magnet to clean it first so I know its clean...Phil

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    I would post information, but reading through the previous comments about Lenz law and such it seems as if the basis is covered. I know that when I cut cast iron then switch to other materials there is some carry over from cast iron suspension in the coolant, but I cannot see the amount of carry over from coolant making the Al magnetic to that magnitude. I do agree with all the posts here about the scrap yards scumbagging whenever possible, I know I have dealt with it before and know of other shops dealing with the same. If you are reliant on the cost coming back for chips, maybe running the chips past a large strong neodymium magnet before the go into the bin.

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    Quote Originally Posted by SShep71 View Post
    I would post information, but reading through the previous comments about Lenz law and such it seems as if the basis is covered. I know that when I cut cast iron then switch to other materials there is some carry over from cast iron suspension in the coolant, but I cannot see the amount of carry over from coolant making the Al magnetic to that magnitude. I do agree with all the posts here about the scrap yards scumbagging whenever possible, I know I have dealt with it before and know of other shops dealing with the same. If you are reliant on the cost coming back for chips, maybe running the chips past a large strong neodymium magnet before the go into the bin.
    I cannot see the amount of carryover from coolant making the Al magnetic either SINCE THE CAST SHOULD BE CUT DRY.

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    Quote Originally Posted by FlatBeltBob View Post
    I took about 60# of what I thought was clean aluminum chips to the recycler the other day.
    I always take great care to clean out my chip pans when changing from steel to alum. wipe up all fines , magnet sweep , paper towels.
    I even run the lathe chips through a chip compactor .
    The guy runs a strong magnet wand and finds lots of places the wand will stick to . So he offers to pay me $ zero for the lot.
    What the hell ! I hate to just throw chips in the trash .
    Is it possible that metal fines in the coolant are sticking to the chips
    in such an amount to be detectable ?

    Of course he does. Why do you think he uses a "magnet wand"?. An honest dealer uses a magnet on a chain so that the attraction is obvious. A "wand" can be held anywhere he wants it to be. There comes a time when you are at fault for being such a "mark". High scrap prices in recent years have brought opportunistic scum into the business who have little knowledge other than how to fuck people.
    In addition the first thing you should scrap is any kind of compaction device for the chips. The oldest trick in the book is crap inside of a bundle. Any such package is suspect and I would not buy it. I spent 25 years in the scrap business and there are things you just don't touch.

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    never seen magnetic alum but i have seen where they use a an alum dish spinning between magnets to slow down land speed cars. it acts as a brake but it can never lock up the tires and it never gets hot cause there isn’t any friction

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    Quote Originally Posted by climb-101 View Post
    never seen magnetic alum but i have seen where they use a an alum dish spinning between magnets to slow down land speed cars. it acts as a brake but it can never lock up the tires and it never gets hot cause there isn’t any friction
    Oooops, the disc does get hot, indeed. The kinetic energy has to dissipate somehow. And it does through heat from eddy currents in the disc. That is exactly how most of the modern exercise bicycles brake the pedals. I’ve spent hundreds of hours in a gym heating up the disc that way. In a rough way, based on the heat of the disc, I could guess the intensity with the of the workout someone had put in.

    Denis

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    Thing is the effect with Ali and a field only happens when either the field or the Ali copper or whatever is moving, correct me if I’m wrong?
    With iron the dust sticks to everything, free graphite included so carryover is possible when coolant flushes the table, pan etc, however I do agree it’s a remote one
    Mark

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    Quote Originally Posted by dgfoster View Post
    Oooops, the disc does get hot, indeed. The kinetic energy has to dissipate somehow. And it does through heat from eddy currents in the disc. That is exactly how most of the modern exercise bicycles brake the pedals. I’ve spent hundreds of hours in a gym heating up the disc that way. In a rough way, based on the heat of the disc, I could guess the intensity with the of the workout someone had put in.

    Denis
    Thank you I was about to jump all over him for that. :-)
    ...lewie...

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    Quote Originally Posted by tdmidget View Post
    I cannot see the amount of carryover from coolant making the Al magnetic either SINCE THE CAST SHOULD BE CUT DRY.

    ...The cast >IS CUT DRY< but the cast iron particulate in the machine from cutting it dry doesn't just magically disappear because "internet", and I don't have time to wipe down the inside of the machine in between parts. The cast iron particulate lays in machine, coolant runs over particulate during next job, coolant/particulate suspension is now in tank and elsewhere in machine...MAGIC!

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    Quote Originally Posted by dgfoster View Post
    Oooops, the disc does get hot, indeed. The kinetic energy has to dissipate somehow. And it does through heat from eddy currents in the disc. That is exactly how most of the modern exercise bicycles brake the pedals. I’ve spent hundreds of hours in a gym heating up the disc that way. In a rough way, based on the heat of the disc, I could guess the intensity with the of the workout someone had put in.


    Denis
    I didn’t realize that the disk heats up, it makes sense though. I should have done a little more research before posting.

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    Aluminum seems to be attracted by gravity...seems most if not all aluminum goes down when you drop it.

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    Quote Originally Posted by climb-101 View Post
    I didn’t realize that the disk heats up, it makes sense though. I should have done a little more research before posting.
    Two trhoughts:
    1) Few people have the courage to admit it when they err.
    2) Most of us come to this site to learn.

    Denis

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    Quote Originally Posted by FlatBeltBob View Post
    I took about 60# of what I thought was clean aluminum chips to the recycler the other day.
    I always take great care to clean out my chip pans when changing from steel to alum. wipe up all fines , magnet sweep , paper towels.
    I even run the lathe chips through a chip compactor .
    The guy runs a strong magnet wand and finds lots of places the wand will stick to . So he offers to pay me $ zero for the lot.
    What the hell ! I hate to just throw chips in the trash .
    Is it possible that metal fines in the coolant are sticking to the chips
    in such an amount to be detectable ?
    The only metals that are magnet are Iron, Nickel and Cobalt.
    Roger

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    Quote Originally Posted by climb-101 View Post
    I didn’t realize that the disk heats up, it makes sense though. I should have done a little more research before posting.
    As should a lot of the posters around here. Pseudo Electronic experts abound in all Mechanical forums. :-)
    ...lewie...

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    Quote Originally Posted by rogertoolmaker View Post
    The only metals that are magnet are Iron, Nickel and Cobalt.
    Roger
    actually there are two other metals, but i never could remember the names.

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    Dollar bills are magnetic too and so is my wallet, to bad they are opposing poles...


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