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Found a neat way to measure relief with a ping test and spectrograph
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UNCLE BINGO
- Posts: 894
- Joined: Fri Jul 29, 2022 11:41 pm
Re: Found a neat way to measure relief with a ping test and spectrograph
Funny thing as i typed the reply to you and then went back to the 1921 twilight zone thing i was looking at . I saw this and if you get any kind of results from pinging and detecting flaws in planchets , i think i will ping this one.
Proud winner of Worst new Vammer of the year 
Re: Found a neat way to measure relief with a ping test and spectrograph
If there are cracks you will notice the coin does not ring as long, if it rings at all. You'll still see spots on the spectograph if you use one, but not lines. Machinists, carpenters, and lots of other trades that work with fast spinning blades or grind wheels will ping them and make sure they ring before using them to check for cracks so they don't explode.
I've been thinking and experimenting with this audio analysis and have come to the conclusion that it is not a useful tool to measure relief. While it is true that two coins with different relief, all other things being equal, would have a wider gap in the two lowest frequencies, there is something else that causes this gap to a much greater degree: being slightly off center or uneven strike pressure. Basically if there is more metal in the rim of the coin on one side than the other this will break the mass distribution symmetry much more than the depth of the design.
To prove this to yourself take a junk coin and file some of the edge off and re ping it and compare the spectrographs. Depending on where you file you can make it wider or thinner, and if you keep filing it will get wider, I could go into more detail but as this is the coin forum not the physics forum I just thought y'all would like to know its not a good method for quantifying relief.
I've been thinking and experimenting with this audio analysis and have come to the conclusion that it is not a useful tool to measure relief. While it is true that two coins with different relief, all other things being equal, would have a wider gap in the two lowest frequencies, there is something else that causes this gap to a much greater degree: being slightly off center or uneven strike pressure. Basically if there is more metal in the rim of the coin on one side than the other this will break the mass distribution symmetry much more than the depth of the design.
To prove this to yourself take a junk coin and file some of the edge off and re ping it and compare the spectrographs. Depending on where you file you can make it wider or thinner, and if you keep filing it will get wider, I could go into more detail but as this is the coin forum not the physics forum I just thought y'all would like to know its not a good method for quantifying relief.
Re: Found a neat way to measure relief with a ping test and spectrograph
I am pursuing this interesting area with the equipment and knowledge I have available to me here, at this time. Disappointing and woefully inadequate so far...I was unable to get the http://friture.org with my OS; which is understandable. I did download two other software apps. courtesy of Google. (I am assuming they are similar to friture's.) They both have quite a learning curve for me to adjust. They worked surprisingly well with ambient noise and a laptop microphone.
I was able to determine a member of my family may be in need of some hearing assistance.
This did not go over well; and kind of put a stop to research in this area, for the time being...I will get back to it and report here.
My thinking is you will need a fine tuned machine to measure the parameters Messydesk mentioned and my mission with an 1878-S anomaly. Great Fun here.
Being able to differentiate a small amount of material removal with a before and after test is very encouraging to me for the application I am dreaming of.
I was able to determine a member of my family may be in need of some hearing assistance.
This did not go over well; and kind of put a stop to research in this area, for the time being...I will get back to it and report here.
My thinking is you will need a fine tuned machine to measure the parameters Messydesk mentioned and my mission with an 1878-S anomaly. Great Fun here.
Being able to differentiate a small amount of material removal with a before and after test is very encouraging to me for the application I am dreaming of.