Signstek Digital Ultrasonic Thickness Gauge Meter Tester, Range 1.2~225mm

Chinese counterfeit gold coins, with tungsten cores, now have the appearance, size, weight & specific gravity of the real thing. This ultrasonic thickness gauge can tell them apart. Tungsten has a significantly higher velocity of sound than gold. When the gauge is set for the sound velocity of gold, a tungsten planchet from Ebay does not match its measured dimensions. The gauge reads a significantly smaller dimension by about one third. Another feature of this gauge is the ability to display the velocity of sound, given the measured dimension. Doing so with the tungsten planchet the gauge displays the published velocity for tungsten almost exactly, (i.e. 5,200 m/s). Getting a good measurement on coins can be a bit fiddly. The ultrasonic beam needs a flat surface to reflect back from. Use a high viscosity couplant gel and aim the beam through the coin at the largest smooth surface you can find. Play with the transducer angle and use the smallest measurement displayed. Bars of metal a much easier to measure. I like to shoot the beam through the long dimension to check as much of the interior metal as possible. Adulteration or foreign inclusions will cause the two measurements to be significantly out of whack. Entering the actual measured dimension into the gauge will give the sound velocity of the material & some idea what you have, (e.g. Lead = 2,200 m/s, Silver = 3,600 m/s, Gold = 3,200 m/s).

I was skeptical, buying this product, because of its price. My company needed to be able to check wall thickness of aluminum castings -- a blind measurement that can't be taken any other way. After using this unit for three weeks now, we have grown to trust its output (particularly because it is so easy to verify its accuracy, by using the 4mm specimen gauge that comes with the unit, as well as the built-in calibration pad mounted (as shown... lowest silver pad in photo). And of course, you can always just pick up a piece of metal of known thickness and check that way, too. Make sure you purchase the blue ultrasonic gel that is needed, for proper measurement contact.I bought the unit without the case. I should have bought it WITH the case. It deserves it.

Excellent product and value for price charged.This item is a good example of previously expensive "Hi-Tech" items, that few non-industrial or institutional buyers could economically justify acquiring; now being made in China and sold at a small fraction of prices that were common for similar instruments a few years ago.It takes some knowledge and skill to use this instrument to its full potential. It will likely help most persons to have a background in subjects like hands on experimental engineering or institutional hard scientific research, when trying to use this instrument.The documentation that comes with the unit is somewhat lacking in clarity; but is sufficient for learning to operate unit effectively within a few hours of experimentation. The manual states that unit comes with liquid coupling agent and a warranty card; but neither was included; and seller's listing does not mention either as being included. Many common materials, including olive oil, make good coupling agents for many applications.A previously written, excellent review mentions purchasing and using this unit to detect fake gold and silver coins and bars. Unit can be a most useful tool for doing so, at a cost that is significantly less than some other testing devices; BUT how to do so reliably (in most of the different cases that one is likely encounter) is beyond the scope of this short review. However, the necessary information is easily found on the Internet by typing in the phrase 'an introduction to ultrasonic thickness gaging' from most search engines.

good product

Great value works good