A specific gravity machine, created by yours truly

So I've always wanted to test my coins non invasively, to see if they are gold or silver or whatever, but preferably without banging them about, exposing them to ice etc.

The specific gravity test is great for this, but a little annoying to setup, and it's quite hard to suspend it in the water securely. So I looked for some specific gravity machines. They are all around $1500.... which is ridiculous. Very few collectors would spend that.

Therefore over the last few weeks I've come up with a workable design that I can build cheaply (for under $200) that will accuracy measure the specific gravity of coins and gemstones etc.

Behold an early design drawing of the "Oggmachine 3000"



This works because we can always measure the volume of the water with the ultrasonic sensors, and we know the volume of the extra parts. Once tilted tiny holes allow the water to flow in for measurement, and then out again maintaining the original environment of the coin or gem.

Currently coding this in spare time, it's actually quite some fun! Once I have a prototype which works, I may put it on kickstarter and allow people to get their hands on one.

In April I made my own and it worked out pretty well. Not as fancy as yours but does what it is supposed to do. See the numbers on scale and compare to chart. My result is 10.34. Pretty cool. (26.68/2.58 = 10.34 - Chart calls for 10.337). Water used is distilled for more accurate results.

Drawings:

Actual:

Step 1:


Step 2:


Chart I use:


I also made a silver slide/racer that was a ton of fun and works like a charm.

Hope it works out for you.

Aaron

Wow, nice work! I like the idea and the engineering behind it!

I tried a magnetic slide once and it worked ok, except that a silver-plated copper coin behaved the same as a solid silver coin. Copper and silver are both diamagnetic... Luckily the weight difference between the two was enough to measure!

Impressive stuff all of you

Quote: "oggy"​So I've always wanted to test my coins non invasively, to see if they are gold or silver or whatever, but preferably without banging them about, exposing them to ice etc.
​
​The specific gravity test is great for this, but a little annoying to setup, and it's quite hard to suspend it in the water securely. So I looked for some specific gravity machines. They are all around $1500.... which is ridiculous. Very few collectors would spend that.
​
​Therefore over the last few weeks I've come up with a workable design that I can build cheaply (for under $200) that will accuracy measure the specific gravity of coins and gemstones etc.
​
​Behold an early design drawing of the "Oggmachine 3000"
​
​
​
​This works because we can always measure the volume of the water with the ultrasonic sensors, and we know the volume of the extra parts. Once tilted tiny holes allow the water to flow in for measurement, and then out again maintaining the original environment of the coin or gem.
​
​Currently coding this in spare time, it's actually quite some fun! Once I have a prototype which works, I may put it on kickstarter and allow people to get their hands on one.

​Nice plan and all the best. Also liked the machine name 'Oggmachine 3000'

Quote: "aaronmgd"​In April I made my own and it worked out pretty well. Not as fancy as yours but does what it is supposed to do. See the numbers on scale and compare to chart. My result is 10.34. Pretty cool. (26.68/2.58 = 10.34 - Chart calls for 10.337). Water used is distilled for more accurate results.
​
​Drawings:
​
​Actual:
​
​Step 1:
​
​
​Step 2:
​
​
​Chart I use:
​
​
​I also made a silver slide/racer that was a ton of fun and works like a charm.
​
​Hope it works out for you.
​
​Aaron

​That's good