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New Testing Equipment: Landtek TM-8812C Ultrasonic Thickness Meter


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I bought a new toy to play with, it's the Landtek TM-8812C ultrasonic thickness meter.   An ultrasonic thickness meter or gauge (UTM or UTG) is just another tool to help you detect fake silver or gold bars.  How does it work?   Basically a UTG tells you the thickness of the material in question.  You first measure the metal's thickness with a digital caliper.   Then you input the sound frequency of the metal in question into the meter and measure the metal with the probe.   The result that you get should be the thickness of the material measured.   If your test results are wildly off, then you know you have a fake.  If your test results are within acceptable variance, it is genuine.

 

The specs of this unit are:                                                             

measuring range: 1.2 ~ 200 mm (0.05 ~ 8 inches)

resolution: 0.01 mm

accuracy: +/- (0.5% + 0.1)

sound velocity: 500 ~ 9,990 m/s

 

UTG Pros:

- it can detect fake bars where other testing equipment says it's genuine (eg. XRF)

- reasonable cost to purchase, when compared to other testing equipment (eg. Sigma Metalytics Pro, XRF)

- works best on 999 purity gold and silver bars

- works best on flat surfaces like bars

 

UTG Cons:

- does not work on metals that are not pure (e.g. American gold eagles are 91.6% pure but contain other metals that can skew the results)

- requires direct contact of probe on the metal (cannot measure with capsule or plastic wrapping on)

- requires the use of a medium between probe and the metal, like glycerin or oil

- bars of different sizes will require probes of different frequencies for optimal testing results (edit: cannot confirm, more testing required)

- cannot use with numismatic coins, as the glycerin medium used for the probe may damage it.  Also the probe may scratch numismatic coin.

- does not work well with coins that have patterns or designs, may give inconsistent results

 

Celerity of common metals, including silver and gold.

Alphabetical   By Velocity of Sound
Metal Velocity of Sound
Aluminum 6,400 M/s
Brass 4,300-4,700 M/s
Copper 4,760 M/s
Gold 3,240 M/s
Iron 5,950 M/s
Cast Iron 4,600 M/s
Lead 2,160 M/s
Nickel 5,600 M/s
Platinum 3,300 M/s
Silver 3,650 M/s
Stainless Steel 5,790 M/s
Tin 3,300 M/s
Tungsten 5,200 M/s
Zinc 4,200 M/s
   
Metal Velocity of Sound
Lead 2,160 M/s
Gold 3,240 M/s
Tin 3,300 M/s
Platinum 3,300 M/s
Silver 3,650 M/s
Zinc 4,200 M/s
Brass 4,300-4,700 M/s
Cast Iron 4,600 M/s
Copper 4,760 M/s
Tungsten 5,200 M/s
Nickel 5,600 M/s
Stainless Steel 5,790 M/s
Iron 5,950 M/s
Aluminum 6,400 M/s

 

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Edited by SilverStorm
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Posted (edited)

Using my 2021 1oz Canadian silver maple leaf as a test coin, I measured my SML with a digital caliper and got an approximate thickness of 3.07 mm.   I inputted the celerity of silver into the TM-8812C, which is 3,650 m/s.  After adding a drop of glycerin onto the SML, I get a measured thickness result of 2.73 mm.   This give a variance of 0.34 mm that is less than actual.   The results can be explained due to 2 possible reasons: first, the SML has patterns and does not have a smooth surface.   Secondly, the standard probe provided with the UTG may not be optimal for measuring precious metals.   As long as the variance is not large, the results is acceptable.   I hope this thread helps you to decide if a UTG is right for you.

Note: the SML test coin was checked twice to confirm authenticity.  Once with the local coin dealer who had the Royal Canadian Mint's Bullion DNA machine (coin was confirmed with RCM's online database); and secondly, with my Sigma Metalytics Pro Mini.   So I am 100% confident that the SML test coin is genuine.   Any testing discrepancies lie with the method of testing or the equipment itself.  And as was mentioned in my first post, the UTG is not recommended for coins (hence the results I obtained).   

 

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Edited by SilverStorm
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Is there no requirement to calibrate your equipment with a calibration block of the same material you are going to test.

Very small changes in velocity will give you false reading. 

There are a lot of variables with Ultrasonic inspection!

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Posted (edited)
10 hours ago, DrunkMonk said:

Is there no requirement to calibrate your equipment with a calibration block of the same material you are going to test.

Very small changes in velocity will give you false reading. 

There are a lot of variables with Ultrasonic inspection!

Yes, you indeed need to calibrate the UTG, the calibration cap is mounted to the side of the device.   I forgot to mention I calibrated the UTG before using.  Thanks for pointing that out though.

You are correct, there are a lot of variables to take into consideration.   I'm still learning, and I hope to have more insights I can share with all as I discover what a UTG can or can't do.   My next step will be testing some silver bars that are thicker.  However I am loathed to take the plastic wrapping off the one I have now (St Helena 250 g bars), as I prefer to keep them as mint as possible.   I'll make a decision one way or another soon enough.

Edited by SilverStorm
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Posted (edited)
4 hours ago, Gordy said:

JUST OUT OF CURIOSITY....  oops caps! how much is it?

I paid USD $212, which includes DHL shipping.  Custom duties and VAT taxes are extra.  

Edited by SilverStorm
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10 hours ago, SilverStorm said:

Yes, you indeed need to calibrate the UTG, the calibration cap is mounted to the side of the device.   I forgot to mention I calibrated the UTG before using.  Thanks for pointing that out though.

You are correct, there are a lot of variables to take into consideration.   I'm still learning, and I hope to have more insights I can share with all as I discover what a UTG can or can't do.   My next step will be testing some silver bars that are thicker.  However I am loathed to take the plastic wrapping off the one I have now (St Helena 250 g bars), as I prefer to keep them as mint as possible.   I'll make a decision one way or another soon enough.

I feel your pain unwrapping a silver bar! Most UT gels are water based so not the best applying it to your silver bar.

Do you know what frequency and crystal size the probe is?   

I do Ultrasonic testing on welds and metals, any questions you have just fire them over.  

TBH if I was testing silver or gold I would probably opt for PMI testing (positive material identification) only due to so many variables with UT. 

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1 hour ago, DrunkMonk said:

I feel your pain unwrapping a silver bar! Most UT gels are water based so not the best applying it to your silver bar.

Do you know what frequency and crystal size the probe is?   

I do Ultrasonic testing on welds and metals, any questions you have just fire them over.  

TBH if I was testing silver or gold I would probably opt for PMI testing (positive material identification) only due to so many variables with UT. 

Wow you have experience with UTG?!?  You are a godsend!   😆

I will post up the specs tomorrow for you to look at.  Thanks DM!

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1 hour ago, SilverStorm said:

Wow you have experience with UTG?!?  You are a godsend!   😆

I will post up the specs tomorrow for you to look at.  Thanks DM

1 hour ago, SilverStorm said:

Wow you have experience with UTG?!?  You are a godsend!   😆

I will post up the specs tomorrow for you to look at.  Thanks DM!

No problem look forward to it.

 DM is fine. 

 

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Hi DrunkMonk, please see attached pdf file for the specifications.   The standard probe has a measuring range of 1.5 ~ 200 mm (for steel), diameter of Ф8 mm, and frequency of 5M Mz.   Other probe attachments that fit are shown on page 2 of the pdf file (probe technical parameters).

Any insights on proper usage, things to look out for, what to do (or not to do), etc is appreciated, and I thank you in advance for your help in this matter.  

 

 UltrasonicThicknessMeter_TM-8812_TM-8811_TM-8810_Catalog.pdf

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Posted (edited)
16 hours ago, DrunkMonk said:

TBH if I was testing silver or gold I would probably opt for PMI testing (positive material identification) only due to so many variables with UT. 

Not familiar with the term "PMI testing" until I looked it up.   But I have heard about XRF though (just didn't know it relates to PMI...I do now!)

Two ways to do PMI testing:

1) XRF (equipment too expensive);

2) optical emission spectroscopy (OES), which I am not familiar with at all, but I'm assuming this equipment is going to very expensive as well.

 

 

Edited by SilverStorm
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7 hours ago, SilverStorm said:

Hi DrunkMonk, please see attached pdf file for the specifications.   The standard probe has a measuring range of 1.5 ~ 200 mm (for steel), diameter of Ф8 mm, and frequency of 5M Mz.   Other probe attachments that fit are shown on page 2 of the pdf file (probe technical parameters).

Any insights on proper usage, things to look out for, what to do (or not to do), etc is appreciated, and I thank you in advance for your help in this matter.  

 

  UltrasonicThicknessMeter_TM-8812_TM-8811_TM-8810_Catalog.pdf 973.29 kB · 1 download

Hi Silver storm,

The biggest worry I would have is UT devices are for measuring thickness and not the actual material, you will get differences in velocity depending on the gold / silver grade.  On a standard UT set we adjust the range & time base to allow for changes in velocity, thickness meters don't have this advantage. 

One way around it would be to measure your 250g bar with the calipers, say it's 8mm, set your velocity to silver 3650 M/s and see what reading you get say its 7.5mm, adjust your velocity until your reading on the UT meter says 8mm, your velocity might then be 3675 M/s, that will be the true velocity of your bar. 

Looking at the probes the probe you have should be ok, the better probe would have been the 5Mhz 6mm thin material probe.

 

 

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8 hours ago, SilverStorm said:

Not familiar with the term "PMI testing" until I looked it up.   But I have heard about XRF though (just didn't know it relates to PMI...I do now!)

Two ways to do PMI testing:

1) XRF (equipment too expensive);

2) optical emission spectroscopy (OES), which I am not familiar with at all, but I'm assuming this equipment is going to very expensive as well.

 

 

These types of testing are both very expensive so probably not worth it, a typical PMI set is around 15-20k. 

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12 hours ago, DrunkMonk said:

Hi Silver storm,

The biggest worry I would have is UT devices are for measuring thickness and not the actual material, you will get differences in velocity depending on the gold / silver grade.  On a standard UT set we adjust the range & time base to allow for changes in velocity, thickness meters don't have this advantage. 

One way around it would be to measure your 250g bar with the calipers, say it's 8mm, set your velocity to silver 3650 M/s and see what reading you get say its 7.5mm, adjust your velocity until your reading on the UT meter says 8mm, your velocity might then be 3675 M/s, that will be the true velocity of your bar. 

Looking at the probes the probe you have should be ok, the better probe would have been the 5Mhz 6mm thin material probe.

 

 

Thanks DrunkMonk for the info.  I have noticed online that the velocity for silver could also be 3600 m/s, so this means there is variability to what the celerity of silver should be.  Most online posts show 3650 m/s.   This is in line with your comment regarding velocity adjustment on the UTG.  Thanks again.

 

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If the range is 8 inches, why not try testing coins sideways, across their longest dimension? Silver one-ouncers are all around 40 mm in diameter, or about 1.57 inches. That way you don't have to worry about their surface features. If it can't test coins, it seems pointless, since all coins have "patterns or designs".

Why can't ultrasonic testers test Crown gold alloy, e.g. the American Gold Eagle? What does ultrasound know about "purity"? It's just a velocity like any other velocity, right? Doesn't the 22 karat alloy used in the Eagle have a characteristic velocity like any other metal? Your table includes brass and stainless steel, which are also alloys, and somewhat less pure than Crown gold (stainless has at least 12% chromium and usually 8-10% nickel, among other things, while Crown gold only has 8.3% non-gold constituents). The Eagles have had the same composition of gold, copper, and silver from their inception, so I don't know why they can't be characterized for testing purposes. (It's a different alloy than other Crown golds, like the Krug, which has no silver, just copper. This is why Eagles are a much prettier color than Krugs. I don't remember if Sovereigns have any silver.)

By the way, what does the Royal Canadian Mint "Bullion DNA" method do exactly? Is it just a high-res photograph/scan of unique imperfections or something, like the PAMP Suisse authentication system?

It's a bummer that we still don't have reliable, simple, and affordable testing tools for bullion at this point in history. I would've thought that a smartphone could be leveraged for such purposes. I don't understand why spectroscopy isn't more affordable at this point.

Edited by Bimetallic
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15 hours ago, Bimetallic said:

If the range is 8 inches, why not try testing coins sideways, across their longest dimension? Silver one-ouncers are all around 40 mm in diameter, or about 1.57 inches. That way you don't have to worry about their surface features. If it can't test coins, it seems pointless, since all coins have "patterns or designs".

Why can't ultrasonic testers test Crown gold alloy, e.g. the American Gold Eagle? What does ultrasound know about "purity"? It's just a velocity like any other velocity, right? Doesn't the 22 karat alloy used in the Eagle have a characteristic velocity like any other metal? Your table includes brass and stainless steel, which are also alloys, and somewhat less pure than Crown gold (stainless has at least 12% chromium and usually 8-10% nickel, among other things, while Crown gold only has 8.3% non-gold constituents). The Eagles have had the same composition of gold, copper, and silver from their inception, so I don't know why they can't be characterized for testing purposes. (It's a different alloy than other Crown golds, like the Krug, which has no silver, just copper. This is why Eagles are a much prettier color than Krugs. I don't remember if Sovereigns have any silver.)

By the way, what does the Royal Canadian Mint "Bullion DNA" method do exactly? Is it just a high-res photograph/scan of unique imperfections or something, like the PAMP Suisse authentication system?

It's a bummer that we still don't have reliable, simple, and affordable testing tools for bullion at this point in history. I would've thought that a smartphone could be leveraged for such purposes. I don't understand why spectroscopy isn't more affordable at this point.

Hi Bimetallic, you bring up good points.   

The coin was tested sideways across the longest dimension.   You can't test the thin reed side of the coin because the sensor probe is way bigger and wider than the reed side of the coin.    

The reason why we only test for pure 999+ metals is because that's what the table provides.  The table wasn't created specifically to test precious metals like gold American Eagles or gold Krugerands, it's bascially a scientific table to provide key velocity rates of known metals.   We are just adapting the use of this table to provide as a guide when we do ultrasonic testing.  Furthermore, someone needs to provide the velocity number for any alloy that is not pure.  Maybe someone with the technical expertise will do so in the future.

For more info on the RCM Bullion DNA, see the below link:

Bullion Coins DNA | The Royal Canadian Mint

As far I as know, the Royal Canadian Mint is the only government mint that has this security feature. 

Agreed it's a bummer you can't get a reliable and affordable testing tool.   Although the UTG has limited application, it doesn't mean its completely useless.  Depending on the situation, it can be a good tool to have.  I'm still tinkering with it, and hopefully I can help members make an informed decision if the UTG is right for them.   Someone has to take one for the team right?   😝

 

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On 14/06/2021 at 18:49, SilverStorm said:

 Someone has to take one for the team right?   

you said to use lubricant, right?

 

all joking aside, its a good idea to look at testing machinery from other industries, to try and find something to re-purpose for gold or silver collectors

It always seemed strange that sigma could make a machine for it, and not have the market instantly flooded by copies from an Eastern source.

surely it could be reversed engineered?

are there no spotty faced tech nerds posting youtube videos on how to make a tester out of a broken microwave? 

or maybe there is some cheap ex-lab equipment we should look out for on auction sites that could be useful?

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Posted (edited)
4 hours ago, greendragon said:

you said to use lubricant, right?

 

all joking aside, its a good idea to look at testing machinery from other industries, to try and find something to re-purpose for gold or silver collectors

It always seemed strange that sigma could make a machine for it, and not have the market instantly flooded by copies from an Eastern source.

surely it could be reversed engineered?

are there no spotty faced tech nerds posting youtube videos on how to make a tester out of a broken microwave? 

or maybe there is some cheap ex-lab equipment we should look out for on auction sites that could be useful?

LOL thanks greendragon!   Maybe I should also load up on some Anusol as well!  😝

Actually I'm glad you mentioned other testing equipment.   There is a "European" version of the Sigma PMV; I am not sure how it compares with the Sigma in terms of functionality and/or accuracy.   See link below to the GoldScreenBox by Goldanalytix:

GoldScreenBox - Electronic Goldtester | Goldanalytix.com - Gold Analyzer (gold-analytix.com)

I'm looking into possibly getting a new magnetic scale tester, but there's not a whole lot of information available.   

I welcome any information or recommendations on PM testing equipment.   

Edited by SilverStorm
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Posted (edited)

Follow Up Testing:

Having just received my 1oz 2021 TSF silver bar this morning, I decided to test the UTG again to see what kind of results I would get.   I got the following results:

1oz 2021 TSF silver bar thickness: 8.32 mm (approx)

UTG measurement (@ 3650 m/s): 8.73 mm for both front and back

Variance: 0.41 mm

A variance of 0.41 mm is really small and in my opinion is satisfactory for calculating (or measuring) margin of error.   If the bar was fake or impure, the variance would be much larger and obvious.   

I took @DrunkMonk advice on changing the celerity.  I went up and down the frequency, and the closest measurement that I got was 8.31 mm @ 3740 m/s.    I'll be honest, I'm not sure if this is the "new" silver celerity for just the sample bar I used, or if it applies to all silver bars.   More testing is required to tabulate data results to confirm.   IMHO, just stick to the known 3650 m/s as the celerity for silver and use common sense/logic to determine if the variance you get on the UTG is within acceptable norm, or so far out that it's guaranteed a fake.  

 

Testing notes: 

- I had to make multiple measurements as the probe is sensitive and gives different readings.   So it's important to write down your findings so you don't get messed up

- I'm not sure if temperature affect the readings (I don't know the answer to this), but the temperature in my office den was climbing slowly as the UTG testing was being carried out.   This may (or may not) be a factor for the fluctuating readings.

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Edited by SilverStorm
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So the ultrasound tester is one-sided? I guess I thought maybe it would bracket the workpiece on both sides, maybe normalizing the opposite surface at least. Does it matter what sort of surface or material you have the workpiece on? (The silver bar in this case.)

I would measure more than once with the calipers given an irregular messy object like that TSF bar. Which reminds me – variance is a property of a distribution. (I'm a social scientist and statistician, maybe too pedantic here.) The mere difference between two measurement methods, just one vs one, I would call a deviation or just a difference. Well, if one measure is viewed as correct, the benchmark, like the calipers here, I'd probably call the difference on the ultrasound its error.

I wonder if there's potential for a simple device with two-sided thickness measurement. That ultrasound is far too sloppy, too far off the true thickness. Almost a half millimeter on an 8 mm object is absurdly inaccurate. It's the 21st century and this is the best they can do? I would accept maybe 0.05 mm error at most, 1/20 mm. I wonder if there's a technology that could do better if it had both sides of the object. Maybe ultrasound, possibly a different kind of inference or algorithm, like bounceback from a tailored opposite surface, or interfering signals coming from opposite sides. Maybe even audible sound waves, an advanced version of the ping test. Or a combination of radio and sonic.

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Posted (edited)
3 hours ago, Bimetallic said:

So the ultrasound tester is one-sided? I guess I thought maybe it would bracket the workpiece on both sides, maybe normalizing the opposite surface at least. Does it matter what sort of surface or material you have the workpiece on? (The silver bar in this case.)

I would measure more than once with the calipers given an irregular messy object like that TSF bar. Which reminds me – variance is a property of a distribution. (I'm a social scientist and statistician, maybe too pedantic here.) The mere difference between two measurement methods, just one vs one, I would call a deviation or just a difference. Well, if one measure is viewed as correct, the benchmark, like the calipers here, I'd probably call the difference on the ultrasound its error.

I wonder if there's potential for a simple device with two-sided thickness measurement. That ultrasound is far too sloppy, too far off the true thickness. Almost a half millimeter on an 8 mm object is absurdly inaccurate. It's the 21st century and this is the best they can do? I would accept maybe 0.05 mm error at most, 1/20 mm. I wonder if there's a technology that could do better if it had both sides of the object. Maybe ultrasound, possibly a different kind of inference or algorithm, like bounceback from a tailored opposite surface, or interfering signals coming from opposite sides. Maybe even audible sound waves, an advanced version of the ping test. Or a combination of radio and sonic.

Yes the ultrasound probe is one-sided.   You need to use the probe on both sides to determine the thickness for the front and back of the bar.   

Good question regarding the surface of my office table (and whether or not it affects the measurement - I have no idea).   It's made of wood with this smooth white layer on top (not sure what it is called...laminate?).   

I should have measured the TSF bar more than once I suppose, but I didn't feel up to it.  Now whether or not the ultrasound is in error needs to be confirmed.   It could be human error (I hope not).  I guess I should find an industrial metal somewhere and test that.  But without knowing the actual thickness of something in advance, it would be a guess.   

I hear you on the sloppiness of the UTG, and you bring up valid points.  You will get no argument from me.  However it's a technology that's intriguing to me, and I wanted to see how this equipment works on precious metals.   My next goal is to see if I can get a hold of a fake bar to test.  Because if the UTG gives you a horrible result from a fake bar, then it really did help you find the fake and it did its job (despite it being off when measuring valid metals).  This would mean it would give you another valid method of testing for authenticity of a PM.  

Now having said all that, it's very possible that the UTG is inaccurate because it's a cheap unit.   Keep in mind that I bought this ultrasound thickness gauge for USD $212 with shipping in.   Before I bought the Landtek, I got 2 quotes from Olympus for their UTG.  Before I could even get a quote, I had to sign off on a US Enhanced Proliferation Control Initiative (EPCI) form.  Basically you are signing off by saying that you won't export the UTG to any countries on the US ban list for nuclear weapons (LOL!)  Their cheapest priced UTG (model 45 MG) goes for Cdn $2,870 + VAT.  The mid line UTG (model EPOCH 650) went for well over Cdn $11K + VAT!    So yeah, it's very probable and possible that the measurement error of the TM-8812C could be due to poor quality.  How do you compare a USD $212 (or Cdn $260) unit vs a Cdn $2,870 or even a $11K+ unit?    You just can't.   It's like comparing a Mini to a Land Rover or a Rolls Royce. 

As a noob on UTG, there is no way for me to ascertain what is "quality" and what I should be looking for in a UTG device.  I'm in uncharted waters looking for answers.  But I guess the proverb "you get what you pay for" may be true in this case.   

 

Edited by SilverStorm
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Update: I was able to get my hands on a fake ASE, and I was able to test it with the UTG.  Using the same 3,740 m/s velocity (as tested on the 1oz TSF bar), the fake ASE clocked in at 2.40 mm.    Actual ASE thickness should be 2.98 mm (calculated difference of 0.58 mm)

I made the following assumption during testing - pure silver is 3,740 m/s (based on multiple testing of the 1oz TSF bar, which the UTG gave as being the closest thickness to actual).   

Fake_ASE_2.thumb.jpg.ae1332b1401e83a0be87138379334a32.jpg

Fake_ASE_UTG_3740.thumb.jpg.7155fadbc1a62f632b6fa0c480523d1f.jpg

 

Next,  I retested my genuine SML at the new 3,740 m/s velocity.   Actual measured thickness is 3.07 mm (from above).   UTG measurement came in at 3.03 mm (calculated difference of 0.04 mm).   

Real_SML_UTG_3740.thumb.jpg.17f3ed62266eb07a5cb0a400249630e7.jpg

 

I have mixed feelings with the results.  On the one hand, the fake ASE came in correctly as being the wrong thickness.  So that worked.   On the other hand, my genuine SML came in 0.04 mm short.   And this measured result took multiple tries, as it gave thickness readings that was way under.  The patterns on the SML gave the UTG a lot of trouble. 

Conclusion:

I would definitely not rely on the UTG to test coins due to the amount of time involved in obtaining multiple sample results, in addition to incorrect readings.  UTG just don't like coins with patterns, so it's usefulness in testing coins is going to be near zero.   However I still think that the UTG can be a useful tool under certain and limited circumstances, like testing silver and gold bars.   As long as the tested material has minimal or no surface patterns, the readings should be good.   I will test a silver bar in the future to confirm this and provide an update on the UTG.   Stay tuned.

Caveat: anyone who is looking to buy a UTG for testing purposes should understand the limitations of what it can (or can't) do.   Do not take the celerity I use at face value.  Review all the comments posted and make an informed decision if this tool is right for you.  

 

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