# My first BB



## rewalston (Oct 9, 2015)

Well, it's not too big, but I'm proud of it. It was a lot harder to get melted than I thought it would be. Because I was working with gold from some pins, foils and what was in my stockpot, there wasn't a whole heck of a lot there. I have NO idea the weight as my scale will only go to .1g so it's below that. Sorry for the picture quality...had to use a small magnifying glass to be able to get my camera to focus on it.

Rusty


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## Shark (Oct 9, 2015)

Glad to see you got it done. The first button makes the work seem worth while.


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## rewalston (Oct 9, 2015)

It was a little less than I expected, but hey it's gold . 

Rusty


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## g_axelsson (Oct 10, 2015)

Put a ruler beside the tiny button and measure the diameter, then you can calculate the volume and weight from the density of gold.

I can't see any pipe but it looks pure. 8) 

I made a similar button once... http://goldrefiningforum.com/phpBB3/viewtopic.php?f=61&t=7056

Göran


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## rewalston (Oct 10, 2015)

Goran, good idea..umm want to walk me through how to calculate the density? I'm fuzzy on that.
Rusty


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## g_axelsson (Oct 10, 2015)

Calculate the volume from the diameter... I work in metric as it's simpler (at least for me). cm, cubic cm = ml, density in gram per ml = 19.30 g/cm3.

http://www.mathopenref.com/spherevolume.html

Measure the diameter d in cm.
vol=4/3*pi*r3 = 4/3*pi*(d/2)3 = 3.14 / 6 * d*d*d cubic cm
Multiply the volume with the density
Weight = volume * density = 3.14/6*d*d*d * 19.30 = 10.10 * d * d * d

If you measure the diameter in mm then you get the weight in milligram, mg

For example, a 1 cm sphere of gold weighs 10.10 * 1 * 1 * 1 = 10.10g
a 0.3 cm spherical button is 10.10 * 0.3 * 0.3 * 0.3 = 0.27 g
try that in mm
a 3 mm spherical button is 10.10 * 3 * 3 * 3 = 270 mg

That'll do it!

Göran


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## rewalston (Oct 10, 2015)

that's not too bad, I thought it would be more difficult for that...I have a digital micrometer that I'll use to measure it.

Rusty


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## rewalston (Oct 10, 2015)

ok using the digital micrometer I got 1.26mm, so using the calculations Goran provided (my calculator actually has PI so I used that function) I got 20.214712389689098236038485050849mg...does that look about right?

Rusty


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## jason_recliner (Oct 10, 2015)

Yep, though you might allow for some rounding and knock two or three digits off.
20mg is also consistent with it not tripping the 0.1g resolution, where 50mg could go either way.

Congratulations on your first shiny.


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## rewalston (Oct 11, 2015)

jason_recliner said:


> Yep, though you might allow for some rounding and knock two or three digits off.
> 20mg is also consistent with it not tripping the 0.1g resolution, where 50mg could go either way.
> 
> Congratulations on your first shiny.


Thank you Jason, I was going to round it off to 20.215mg, but well you know how it goes...precision is the key :lol: 

Rusty

PS: added a picture of it sitting next to a dime for reference on the case of my scale.


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## g_axelsson (Oct 11, 2015)

That's not precision, that's ignorance of how precision is calculated. Oh, no, you awoke the engineer in me! :twisted: 

Consider your measurement of 1.26 mm, even without considering other errors as not being perfectly round, it's scale implies that the real diameter is somewhere between 1.255 and 1.265. Just plugging this into the formula gives a total weight of 19,9750147313 to 20,4563199331 mg. We now see that the weight could vary almost half a mg from the initial precision. (Haven't considered changes in gold composition or temperature that would affect the density.)

So the correct way to write the weight would be 20 mg, [20.0,20.5] mg or 20.23 +/- 0.24 mg to convey the correct range of possible weights. To use 32 digits of precision claims a measurement precision of sub electronic size... no, not subatomic, that's too imprecise. :mrgreen: 

Sorry, just having a bit of fun with my engineering and physicist background...

Göran


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## rewalston (Oct 11, 2015)

Hey it's all fun, Goran. That's what is great about this forum...it's fun. Now it's time to start collecting more, stuff to refine...but that's going to take some time. No vehicle nor finances to procure stuff to work on...I'm sure that in my washes I have more gold someplace. I think (not sure) that I may or may not have had a false positive with my stannous test on the solution after the gold dropped. It (the solution) either went in my copper pot or my iron pot, can't remember which. Either way gold will be in the sediment as it drops from solution. I'll get it eventually.

Rusty


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