Wednesday, October 13, 2010

Technique for finding deep nickels (Minelab Explorer SE)

Some of you may know that I recently purchased a Minelab Explore SE and have been having good luck recovering old nickels. Lots of the 'hunted out' spots are definitely pretty cleaned out, but everyone loves to leave behind the old nickels. I started to change my strategy a bit and focus on these, since I love finding old V-Nickels and Buffalos.

I've been hunting with the new SE for about 2.5 months. The ground finally became semi-thawed in late-February, so I have been doing most of my detecting in March and April. My nickel tally for this year in this short time is as follows:

1 Shield Nickel
11 V-Nickels
13 Buffalo Nickels
4 Jefferson War Nickels

I've found a few old Jeffersons, but don't like to 'count' them unless they're the war nickels.

As I've been posting my finds on various forums including the DetectorBase.com forum, I often get private messaged, emailed and asked about how I'm finding these. "What program are you using?" "What are your settings?" "Are you digging a ton of pull tabs to find these?"

I thought I'd take this time to contribute a non-web site related article and explain my technique on recovering old nickels. My technique will obviously be based on the Minelab Explore SE, but could be applied to other machines easily.

Before the Minelab, I was using the White's XLT and was having good luck recovering nickels as well. With nickels it's important to know the behaviour of the coin when it's in the ground. We have some basic principles that we can usually assume.

1. Nickels are larger than pennies and dimes.
2. Nickels corrode heavily when underground for many years.
3. Nickels can ID as pull tabs.

Items 1 and 3 are obvious, but item 2 might not be so obvious if you've never pulled a deep nickel. Just like with copper, you can get heavy corrosion with nickels. This corrosion can cause a 'halo' around the coin, providing extra mineralization that can confuse machines.

When I was using the XLT, I noticed that nickels deep in the ground ( > 4 inches) could span multiple VDIs, ranging from +20 to +50. Based off information provided by the signagraph and depth of the target, I would investigate further.

The Minelab Explorer IDs much better in my opinion. No matter how deep or how corroded, the target generally IDs in the nickel range. This makes that part much easier with the Minelab.

The interesting part when dealing with the Explorer is the discrimination. I've adopted the 'All Metal' approach, meaning I hear every signal under the coil. I've been recommended to switch to Ferrous tones and 'All Metal', and I will say, switching to this has revolutionized my detecting. Finds are up, and I have a much better understanding of targets. I believe the single greatest benefit for going 'All Metal' is to avoid nulling or blanking when sweeping your coil.

I would see mention of this early in my swinging days, but didn't fully understand what this meant so I'll explain it for the rookies out there. Basically, if your coil goes over a nail, for example, your discrimination will kick in to prevent the beep. Your threshold will break and there will be a small moment of silence while the coil goes over the nail. The issue is that if there is a coin next or near the signal, the machine may not recover in time to let you know about it, or you get a broken good tone (half nulled/half beep which you might think is junk). Going 'All Metal' you will hear both signals clearly.

The cons of 'All Metal', it is not for everyone, and it will take some getting use to.

Using the factory preset for coins, the discrimination pattern looks like the following:

This is a great disc pattern, but you could be missing deep nickels. Even though, the SE reads deep nickels as correctly as 'nickel', it does fluctuate slightly.

Here is a image of SmartFind with IronMask at 32 (All Metal), but the cursor is at the classic nickel location.

Now, this cursor can fluctuate left, right and up down slightly, but generally be in this area. Overlaying the stock discrimination pattern you'll notice that it could possibly be clipped.

Converting to "All Metal" you won't have to worry about missing these, or if you adjust your pattern to include a wider area around the target zone. Now, the above is fairly obvious. Nickel is showing up as Nickel... everyone can handle that. When I go out to "hunted out" parks and recover nickels, I do NOT have a collection bag full of pull tabs or foil. This is where it takes a bit more work and "risk". The risk is you might miss a few recoveries.

The first thing I do when I get a good nickel tone, is check the cursor position. If it's in the 'zone', I check the depth. If the depth is over 5", then we're in a good time period. No pull tabs in 1920, etc. This target is looking like a likely candidate for nickel. The next piece of the puzzle is the pinpoint.

Pinpointing is a valuable tool, and goes further than finding where the target is. I use pinpoint to "feel" the target. I'm feeling for two things. I'm feeling for the size of the object, and I'm feeling for the halo.

The Explorer SE has a very irritating trait. If there is a tiny target on the surface, the depth will be inaccurate and say it's deeper, when in fact it's on the surface or just below it. I can determine surface targets by the shape of the pinpoint. If I pinpoint left to right and front to back, and the signal cuts off sharply past the center, it's most likely a close target. What I want to feel is the nice "round" pinpoint shape. I'm not referring to the object, but the gradual intensity towards the center and gradual release when I go past it. This is a sign of a deep target with corrosion. This usually applies for nickels laying flat or on edge. This fade of signal strength (in my experience) is more pronounced with nickels than pennies and silver, so it's not as gradual with those coins.

This is basically my technique in a nutshell. This is not meant to be applied for every area. This is mainly focused for deep finds in hunted out parks, lots and lawns. If old nickels are near the surface, you'll want to be digging the pull tabs and foil. I think you'll be impressed with how many nickels are left behind.

For this technique to be apply to other machines, lower your discrimination to include a wider range around nickels. Depending on what unit you have, IDs can fluctuate. Learn to combine factors like depth and pinpoint strength to determine the target. Understand your environment, know where pull tabs and older coins are in the ground time line of your hunting area.

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