How Well Do You Know Your Metal Detector?

If you are new to the hobby of metal detecting, you have probably heard the term “air test” or “nail test” thrown around once or twice.  If you were to ask many experienced metal detectorists what they think about air or bench tests, the response is often loud and clear... 

Air tests are worthless.   Nail tests?  What a joke!  A test garden in the backyard?  A waste of time!  

Twist it and spin it any way you like.  Certain metal detectorists just do not like to bench test their metal detectors.  They very well may even scoff at the suggestion of it in forum or blog posts.  In their eyes, you should take your relic machine and go hunt a nail infested relic site to learn.  You should take you gold detector and go find gold.  Testing is rubbish.   

While I will never say somebody is wrong because they do something different, I just cannot subscribe to that logic.  I think many veterans of this hobby forget what it was like to be a rookie.  There is a learning curve to almost everything in life and metal detecting is no different.  There is tremendous value in testing your metal detector in multiple ways - no matter how long you have been in the hobby. 

Now let me be clear in saying I am not throwing a blanket statement onto all experienced metal detectorists.  There are many who do like to use bench tests to draw conclusions.  Doing a quick Google image search for “nail board test” will bring up a popular test created by a seasoned metal detectorist named Monte. (see image below)  Proving that not all veterans of the hobby are so dismissive of bench testing.



What about the people who are not veterans?  What is a person to do when they have just bought their first detector and have not spent a single second in the field?   I certainly cannot recommend sending them to a nail infested relic site and say “learn your machine”.  So how is a newb supposed to learn anything past the instruction manual? 

With testing of course!

If you know for a fact that relic hunting will be your specialty - test how your detector responds around nails BEFORE the trip.  If you are planning on gold detecting - know how small nuggets respond BEFORE you venture out.  

Well, what are these tests then?  Well, there are many.   So we will take a look at a few that are the most popular.   But do NOT be afraid to make up your own tests and patterns and see how your detector does!

Coin and Jewelry Tests:

This is probably the first test you should do after you read the manual and learn the settings.  It is also the easiest of the tests to perform.  Unless you are strictly into gold prospecting - you will want to know what coins and rings sound and ID as.   

It’s simple.  Grab the most common coins that are minted in your country.  Then go grab a silver or gold ring (or whatever jewelry you have).  Maybe some pull tabs and bottle caps to check those as well.  

Wave them over the coil one by one and PAY ATTENTION! 

Is there a tone change if using a multi-tone machine? 

Is there an ID change if using a detector with a display? 

Where do you have to thumb the discrimination knob on your single tone analog detector until it starts to crackle?

Use a ruler to see how far out you can wave an object before it starts to change ID or tone and finally disappear. 

It’s a very easy test to do and it is invaluable when it comes to learning how coins and jewelry sounds and IDs.   The next obvious step would be to bury the coins.  


Test Bed or Test Garden:

This is similar to the coin testing above, but the coins are buried in the dirt at various depths. 

Take coins and bury them at 3 different depths about a foot apart.  One at 4 inches, one at 6 inches, and one at 8 inches.   Do you notice changes in the ID or tone as you pass over each one? 

Now try it with 3 smaller coins.  Notice how the tone and ID changes (or doesn’t).  Take as many mental notes as you can so you know what the deep coins sound like compared to the shallow coins. 

Nail Tests:

For all the relic hunters of the world - there is usually one standard to go by.   Montes nail board test that was pictured above.  It is by far the most popular test used to see how a metal detector performs in nail infested sites.

It works by discriminating out the nails (or making them iron tone) and then placing a coin (usually a zinc penny) on the #1 spot.  Then wave the coil in the 4 directions the arrows are guiding.  If the coin is picked up as a good signal it is considered a pass.   After all 4 directions, you move the coin onto the #2 spot and repeat the test.

Raised Nail Test:

The nail board test is on a level surface.   What happens when the treasure is buried UNDER the trash?  It changes the whole game is what happens.

You can also replicate this above ground by placing a coin on the surface and then placing a couple of thick books or 2x4 boards next to it.   Then place nails on the books/board above the coin. Wave your coil over the nails and see how it responds.   Check the ID and listen to the tones. See the picture below.

The Long Nail:

This is another very easy test that MANY detectors struggle with.   DD coils struggle here as well - while concentric coils usually do very well.

Place a nail (use different sizes) next to a coin - longways.  Does it pick up the coin if the nail is discriminated out?  See picture below.

Recovery Speed:

Yet another simple test to perform.   It tests how fast your detector can pick up a target before resetting itself to be ready for the next target.

Recovery speed is VERY important in trashy sites.

Place 4 similar coins out at an interval as wide as your search coil.  Usually, 8 inches apart will work.   Wave your coil over all the coins back and forth at an increasing speed until the detector starts to miss the middle 2 coins.   Once it starts to miss - you are swinging too fast.  Back off a bit until all 4 coins sound off clearly.  This speed is basically as fast you can swing your coil without missing targets side by side in the field.   It is your “recovery speed”.   

Separation Test:

Easy-peasy yet again.   Just place 2 objects such as coins at 8 inches apart and wave the coil over both.   It picks them both up easily correct?

Now move the 2 objects closer together to 7 inches and try.   Then 6...then 5...etc. 

How close can you get the two coins before they sound like one coin? 

These are just a few of the more popular ways to test your detector.  Make up your own - search the internet forums for more.   They are out there.  

Remember guys and gals, there is absolutely NOTHING wrong with testing and learning your detector with mock up tests.   Be confident you KNOW how your detector works before you ever step out into the wild.  Test it and then test it again.  It’s fun, it brings you knowledge and confidence, and it makes the old timers grumpy.  That’s worth it right there!

Hope you enjoyed this blog!

John Schmidt (TheHunterGT) signing off.  I will see you on the next blog!