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  1. #1
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    Default How do I tell if it's aluminium?

    I've got some old pumps and things here that have been chucked out. The housings are some sort of cast alloy, not ferrous (magnet wont stick), could be aluminium. Does anyone know of a way to tell what they are? I'm planning to build a furnace later this year and do some sand casting.

  2. #2
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    Easy. Just get yourself one of these. I don't think they sell them at Bunnies though.


  3. #3
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    Guffaw guffaw!!


  4. #4
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    For casting you are probably going to mix diffent compositions of aluminum anyway so I wouldn't get too worried about the purity. If you scratch it and it is bright and it is about the right weight for alloy then throw it in a bag, hit it with the sledge hammer and chuck it in the pot with the coke cans and mower parts.
    Cheers,
    Rod

  5. #5
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    Sounds good to me.

    Though it could be a zinc alloy. Some of the stuff I plan to make can be made from pot metal but I think some parts need to be aluminium. I'll have to read up on it a bit more.

  6. #6
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    The specific gravity of aluminium is 7.7. If you know someone in a Uni geology department with access to a Walker's steelyard, it is fairly easy to measure specific gravity. A bit lower tech than a mass spectrometer, but works fine.

    Rocker

  7. #7
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    Hmm, what I was hoping for was something like the spark test you can use on steel.

    I suppose I'll just have to suck it and see. I don't know many geologists, only one retired bloke and he is too far away to be of much assistance in this case

  8. #8
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    The specific gravity of aluminium is actually 2.7 grams per cubic centimetre. You could work out the volume of a piece by throwing it into a measuring cylinder of water and measuring how much the volume in the cylinder increases. Weigh the dry piece of metal before you throw it into the water and you can then work out its density (or specific gravity).
    Regards,
    Ian.

    A larger version of my avatar picture can be found here. It is a scan of the front cover of the May 1960 issue of Woodworker magazine.

  9. #9
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    Aluminium is non-sparking.
    Regards,
    Ian.

    A larger version of my avatar picture can be found here. It is a scan of the front cover of the May 1960 issue of Woodworker magazine.

  10. #10
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    So's wood
    "Clear, Ease Springs"
    www.Stu's Shed.com


  11. #11
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    Yeah I know but I thought there might have been a similar test, you know a rule of thumb type thing. Zinc alloy is non-sparking too (I think) so I can't use that to tell.

    I guess I'd need some pretty accurate scales and a cyclinder with accurate graduations. I wonder how close the specific weight of aluminium is to other light alloys like magnesium etc..

  12. #12
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    Magnesium is 1.738 g/cm3 and zinc is 7.14g/cm3.
    Regards,
    Ian.

    A larger version of my avatar picture can be found here. It is a scan of the front cover of the May 1960 issue of Woodworker magazine.

  13. #13
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    Default

    Quote Originally Posted by Stuart. View Post
    So's wood
    The recycled stuff I was cutting the other day sparked quite nicely.....
    Retired member

  14. #14
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    Flame tests can be used to determine qualitatively what elements may be present but some groups of metals give similar colours when subjected to such tests. For example, aluminium, magnesium and titanium all produce a silvery/white flame when flame tested. You could do a rough flame test with an oxy torch and without the cobalt blue glass. Be careful though, magnesium burns like buggery if you heat it up too much so just use a small sample.
    Regards,
    Ian.

    A larger version of my avatar picture can be found here. It is a scan of the front cover of the May 1960 issue of Woodworker magazine.

  15. #15
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    Quote Originally Posted by Mirboo View Post
    Magnesium is 1.738 g/cm3 and zinc is 7.14g/cm3.
    That would be in pure form though, wouldn't it? An alloy would be less dense perhaps, depending on what other metals are in it?

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