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Mark Gillespie

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Posts posted by Mark Gillespie

  1. On 2/26/2019 at 12:15 PM, Mark Gillespie said:

     

    Specific gravity is 7.878

    Usually, the density of mild steel is 7.85 g / c m 3 . But, depending on the alloying elements added, this can vary between 7.75 and 8.05 g / c m 3 .

    specific gravity of mild steel may vary between 7.75 and 8.05 g / c m 3 , at 4 o C

     

     

  2. 9 hours ago, Noah (FL) said:

    It really comes down to them loosing or maybe just not competing in the changing world of marketing.  The companies selling tone and visual ID detectors have sold the necessity of distinguishing a penny from a dime or a nickel from a pulltab.  “Coin shooting” is great and all and the potential for a windfall coin find is out there but none of the forms of ID are of much help in distinguishing a gold ring from a pulltab or a gold chain or earring from a bit of foil.

    Don’t get me wrong as I do enjoy using these more modern detectors as well but most of my detecting time is spent jewelry hunting and for that a Tesoro is hard to beat. I have confidence in them and that is the most important thing.  

    In a selfish sense I am glad everyone doesn’t have a Compadre.  If they did there would be a lot less gold hiding in the playgrounds for me to find!!!

    You have a very good point.  Back in the day, I had a Vaquero and a Tejon.  Both had fantastic audio capabilities.  In fact, I did find a lot more gold rings than I tend to find now.  But now, with all the high tech visual ID screens I find myself relying more on what it indicates, rather than a pure audio response and for sure I've walked right over rings thinking they might be junk.

    The Compadre is another fine machine for hunting for lost gold items in playgrounds.  Partly contributed by the small coil and the unique audio.

     

     

     

    • Like 2
  3. 57 minutes ago, Swampstomper Al said:

    Hi.. We're going to need a bit more input from your chief machinist: Upon which scale is " 33 " based?, meaning Rockwell A, Rockwell B etc., not bathroom or gram.. The machine and method used too please..

    It should be mentioned the " 33 " could be inexact regardless which scale was used, primarily due to during setup for greatest accuracy a painfully flat standardized material is used.. It takes only a slight variance at the subject test point to throw off the reading 10 points.. Just saying, while assuming accuracy..

    I have no idea what " ID = 12 " is supposed to represent..

    Not wanting to be a bummer here, merely pointing out we're still missing some vital information to name it and claim it..

    Here's a couple charts that hopefully will be helpful up the road: 
     metal-hardness-chart.png?fit=min&q=50&w=780

    Image result for hardness of metals list

    Image result for hardness of metals list

    Swamp
    A nickel on my machine is a 13, the metal piece was a 12.

    Rockwell C 33
    PS: Gilding Metal = 95% Cu, 5% Zn..

    C SCALE

    • Like 1
  4. I've got two updates:

    It is non-ferrous and the chief machinist where I work is going to check the metal with a hardness analyzer, what ever that is.  Once I have a hardness value I'll be able to compare that to known metal hardness values.

    Just another bit of information.

     He has a complete machine shop at his home where he makes knives from steel.  I'll update tomorrow. 

     

    • Like 1
  5. I might add something that I fell for several years ago.  Tom, down in Florida was promoting the Fisher F75 very heavily.  Explaining how deep it could go, how fast it was and how much more could be found and I,  before thinking had fallen for all the hype, well maybe not hype in Florida.  Now I can say the F75 is a good machine, might go deeper, is faster and might find more but to the levels of Florida, NO.

    In the red/orange clay dirt of Virginia, it struggles just like any other of the VLF machines I've had in the past.  I listened to the "you must run this machine hot" to get the depth but not in Virginia or for that matter anywhere the ground is high in minerals.  But in the white sand, no minerals of Florida, YES.

     

     

     

    • Like 2
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