Avoiding Bottlecaps with MXT Pro

[Bryannagirl]

I just did a hunt with my new to me MXT Pro with SEF 6x8 coil. I was finding a ton of bottle caps - did find an Indian head that read almost the same except was deeper. Question is there a way to minimize bottle cap hits

 

[Larry (IL)]

I'm not familiar with the MXT Pro but the SEF and DD style coils are well known for loving bottle caps. While hunting in bottlecap infected ground, you might want to go to a concentric coil like the 950 or in severe trash the 5.3.

 

[Monte]

I just did a hunt with my new to me MXT Pro with SEF 6x8 coil. I was finding a ton of bottle caps

If bottle caps are in an area we are hunting, we can't 'avoid' them. Bottle Caps, also referred to as "Crown Caps" and not to be confused with aluminum Screw Caps, are quite a pain to deal with because they can be plentiful, especially in older, long-used picnic type areas, etc. They are also a problem because they are a ferrous-based target that is man-shaped into a form that adds to our frustrations.

To add to your frustrations, you were using a Double-D coil. Generally, Double-D coils designs have a bit more problem compared with Concentric search coils. A lot will depend on how a detector is designed to work with different coil types, and some makes do a little better with Bottle Caps using a DD than a Concentric. Most of the time, however, BC's produce more of an up-scale TID read-out with a DD than a Concentric.

That's one reason why I prefer Concentric search coils with the MXT Pro, relying on the 9" 'spider' Concentric for open areas that are more sparse with targets, or the 6½" diameter Concentric for most hunting because I search trashy sites most often. I have used many DD coil sizes and shapes on the MXT series models and none work as well, for me, as a good Concentric coil in trashy sites, especially when it is iron-based junk to deal with.

Bottle Caps might sound good and look good on a visual display, regardless of the search coil or detector used, or they can respond with a more broken or inconsistent audio and/or visual response. Nonetheless, they are still there, we can't 'avoid' them, and have to learn to deal with them as best we can.

- did find an Indian head that read almost the same except was deeper.

Congrats on the Indian Head cent find, and you pointed out a couple of things to remember.

One, if we are patient and work a site as best we can, and probably have to encounter and recover/remove some Bottle Caps or other trash, good targets can be found.

Two, some desired targets just happen to 'read' similar to some unwanted junk, and visa-versa.

Three, we will often find desired targets a little deeper than trash, or restated, a lot of trash, such as discarded Bottle Caps, are often located at a shallower depth.

Question is there a way to minimize bottle cap hits?

You can only "minimize" Bottle Caps at any site by eliminating them. That means to not discard them in the first place, or removed them when encountered when metal detecting. Since we were not there to prevent them being deposited at a site, the best we can do is recover and remove them. Once we accomplish that task, we will have less bad-target annoyance and remove a masking piece of junk. That will then allow us to find any close-by desired targets, if they are there.

Finally, we can take the approach of learning to Deal with Bottle Caps, or learn how to possibly identify them or "classify" then as an unwanted ferrous-based target which they are. Due to the efforts of man to take a crappy hunk of magnetic material and shape it into something useful, the end result is a junk targets with enough conductivity that it can produce a higher-conductive, up-scale reading with most detector on a center-of-coil sweep.

I had moved from using BFO's mainly from '65 through early '71 to basic TR metal/mineral locators in May of '71. When I started using Compass TR's, especially with smaller 6" coils to work trashier areas around picnic tables, I soon learned how to 'classify' probable Bottle Caps. There were quite a few unique search coil designs in use back then, but the Compass TR's [size=small](straight TR's before they had Discrimination)[/size] used round-shaped, Double-D search coils.

Those required a little more off-center sweep to help 'classify' Bottle Caps as well as rusty tin I encountered in ghost towns, etc. In time I went to TR-Disc. models and progressed to newer detector and coil designs, and preferred a good Concentric type search coils since about '78 or so. Because I hunted sites with rusty tin and bottle caps, which seemed to be more in use back then, and since most of the ferrous-based trash was/is located rather shallow most of the time, it was to my benefit to 'classify' a lot of that trash to reduce the number of target recoveries made, increasing my coin-to-trash recovery ratio.

Initially the technique I used, and coined the phrase for, was "EPR" for "Edge=Pass Rejection", and that was easy to accomplish with the basic TR because sweep speed motion wasn't a factor like today. Once I locate and 'isolate' [size=small](pinpoint)[/size] a probable target, I just make a few short side-to-side sweeps as I pull the search coil back toward me. A coin will continue to provide a good response until it isn't having a significant influence on the EMF. But a Bottle Cap or hunk of rusty tine will start to degrade and change from a positive response to a 'proper' nulling response when close to the 'Edge' of the search coil.

With a Concentric coil, the "Edge-Pass" area will be about ½" to 1" or so inform the edge of the coil towards the center. With a Double-D type of a search coil, the "Edge-Pass" are is usually from close to the tip edge of the search coil out away from the coil about ½" to 1" or so. I have taught individuals about this technique, as well as "Quick-Out" which is another method that often works with modern motion-based Discriminators. With out modern TID models, or those with Tone ID, use of "EPR" and/or "Quick-Out" will help provide a 'proper' Iron TID read-out and/or low-tone Iron Audio.

Is it perfect? No, but nothing is 'perfect' when it comes to detecting. You could have a good target too close to the Bottle Cap that could be masked, unless you remove the BC.

Is it useful? It certainly can be and I have used it successfully for over four decades, and have instructed this in my seminars since 1981. I talk about it under Audio Target Classification in the Tips & Techniques section at our AHRPS organization site. I have been with clubs/groups and had a one-time access to hunt old picnic groves with dated use from the twenties through the fifties. I wanted silver, not trash, and Bottle Caps were everywhere. By using these techniques I recovered an absolute minimum number of BC's and had some impressive coin recovery totals as more times was spent getting them out of the ground instead of junk.

So, yes, you can do this with your MXT Pro, and my advise would switch to a 6½" Concentric coil from a Double-D to more easily deal with Bottle Caps.

Monte

 

[Scottowl]

I don't have the Pro, just the Tracker.
When I first started using it a few years back, I started in C&J mode, but went to Relic mode soon thereafter to cut down on the noise.
I was fooling around with the detector tonight, and switched back to C&J. Wow, how noisy. I was directly under transmission lines of a major hydro electric dam, and the interference was present.
I did notice a brief nulling of bottlecaps in this mode, which I had not heard in Relic mode.
I will continue in Relic mode (MUCH! smoother), but the C&J mode may be a tool to use briefly on iffy signals to detect the presence of iron.

 

[Bryannagirl]

Thanks Monte - amazing response thank you so much. I was wondering if you have ever tried using the prospect modes iron probability to help spot the ferrous bottle cap vs the non ferrous coin. Seems like bottlecaps may show some iron percentage you would not see on a coin.

 

[PSS1963]

Thanks Monte - amazing response thank you so much. I was wondering if you have ever tried using the prospect modes iron probability to help spot the ferrous bottle cap vs the non ferrous coin. Seems like bottle caps may show some iron percentage you would not see on a coin.

That's a great question! I was wondering the same thing on Friday but I haven't tried it yet.

You're up Monte!

-pete

 

[Monte]

Thanks Monte - amazing response thank you so much.

I don't know about it being 'amazing,' I just 'Thank You' for letting me know it might have been helpful. That's always my intent with most forum responses, is to try and help others.

I was wondering if you have ever tried using the prospect modes iron probability to help spot the ferrous bottle cap vs the non ferrous coin. Seems like bottlecaps may show some iron percentage you would not see on a coin.

Have I tried it? Yes, a long time ago after I got my first original MXT after their introduction. Can it help separate Bottle Caps from non-ferrous Coins? Yes, kind of, but if a coin is located close to a bottle cap or other ferrous-based piece of junk, the greater-influence ferrous has on the EMF [size=small](which tends to cause good target masking)[/size] will often degrade a favorable target's response. That's why good things by bad things often read 'wrong.'

I've been shopping for a different vehicle and am going to sell or trade them so I have been keeping a limited amount of stuff in them, and lately only my FORS CoRe and Racer. A friend is making use of my MXT All-Pro or I'd double check it now, but there's no real need because if you have an MXT, you can do that check yourself. On the other hand, if I had my MXT All-Pro at my side right now, I still might not be too enthused about doing it for a few 'simple' reasons ... the key word, naturally, being 'simple.'

I like 'simple' when it comes to detector adjustment functions, as long as a unit is still functional and provides desired performance. Because I don't like to tinker with a lot of settings just to have to tinker around when I move a few yards away and encounter different conditions. My favorite metal detectors are those that lack a lot of 'fluff' and/or I can just make the FEW adjustments needed and get busy detecting. Here are a few examples of what have enjoyed using and the easy ready-set-go process I take to enjoy detecting.:

With a Teknetics Omega I set the Sensitivity as high as possible w/o being unstable. I set the Discrimination at the minimum of '1', or if there are a lot of iron nails around I use no more rejection than '16'/'17' to just barely reject nails. Then I select the 2-Tone Audio for most locations and search. If I am after modern coinage in typical urban coin hunting locations, I choose 4-Tone Audio.

With a Tesoro Bandido II µMAX I use the highest Sensitivity most of the time, w/o instability, and set the Discrimination at the minimum setting and never any higher.

Using a White's MX5 I set the Sensitivity at '8' bars, or up to '10' if there's no instability, and I reject no more than just the first three Discrimination segments. That's all it takes to reject the iron nails. If I make any other change it is to accept all Disc. segments. I prefer the 2-Tone Audio 95% of the time or more.

The MXT Pro or All-Pro [size=small](same detector)[/size] I usually use maximum Gain [size=small](+3)[/size] unless it is unstable then I reduce it. I set the Discrimination level no higher than between 2 and 3 to just barely reject iron nails, If not, I reduce it to the minimum '0' Disc. In the Relic mode I might use the 2-Tone audio, or I opt for Iron ID [size=small](which bypasses the Discriminate control and simply separates most ferrous and non-ferrous targets)[/size].

Using the Nokta FORS CoRe or Makro Racer [size=small](similar settings and functions)[/size] I usually run the Gain at '85', the Discrimination at '10' in 2-Tone Audio or '23' [size=small](for iron nail rejection)[/size] in 3-Tone Audio.

Notice the similarities? They are simple to set-up, no more Discrimination than to reject iron nails, if that, and I usually bump the Gain up ... unless there is EMI present OR unless I am in a densely littered area where I opt to reduce the Gain/Sensitivity.

I will hunt in the All Metal mode, if a site is quite target-sparse, and in all cases and in any search mode, I will adjust the Ground Balance and leave it set as desired. I seldom use auto-tracking GB, with the exception of the MX5 which has no 'lock.' capability.

I know this might sound like a lot to people, but it isn't. Some models save the desired settings or you can turn the detector 'On' and have all settings made and be searching in 15 to 20 seconds. Then, when I am hunting a site with those blasted crown-cap type Bottle Caps, instead or trying different search modes or the All Metal iron percentage read-out and a lot of 'tinkering,' it is much quicker to just use the "Quick-Out" and "EPR" techniques that I have grown accustomed to, having used it since '71 or before. I did it then with 'simple' detectors using Double-D coils [size=small](the basic Compass TR's)[/size] as well as other makes and models with many different search coils, for almost four-and-a-half decades. Why change.

Remember, nothing is 'perfect' and we usually deal with Bottle Caps that are in plain sight or that might be down to 1" to 3" and, in those ranges, you can usually use the techniques I mentioned, and never have to change settings or search modes. Just use a moment to isolate/pinpoint a suspected target and make a quick off-center coil sweep as needed based upon the detector and coil you are using. It works on Bottle Caps and all sorts of annoying ferrous-based junk.

Monte

 

[bula]

I hunt in cj mode all the time, I have found that where I hunt the vdi will bounce around when over a cap. Years of hunting and this has always been the same. If the vdi is not solid I don't dig.

 

[Nancy-IL]

Hi Bula, Good seeing you on here again. How ya been?

I'm with you, I hunt the same way. The only thing is that those Indian cents likes to make the VDI dance around also. So in private property, I dig those signals. HH, Nancy

 

[pescadore]

Called a couple yesterday before I dug them and sure enough they were caps. I use the same method by noticing the jumpy signals especially when swinging from different directions.

 

[Bryannagirl]

I think the other thing that helps is knowing the site. Where I hunt now most caps are no more then an inch deep. Good targets (fresh clad not included) is about 2 to 4 inches. The difficult thing is the junk is so prevalent that you know it is masking a lot of good stuff. I have a 5x10 and 6x8 non White's coils and 5.3 inch White's coil to try and see between the junk and bottlecaps. Still not sure which one is the best. Maybe the 5.3 concentric. Have also heard good things about 4x6 shooter from White's.

I am finding good targets in and around bottlecaps just not right over a target. Also, I did try the prospect mode to check iron in bottle caps. The jury is still out but it did seem that I got high iron probability with bottlecaps.

 

[bula]

The voice of experience, forgot about those Indians. Doing good Nancy but running out of spots to hunt. I see you and your better half are still hitting it hard & finding some good stuff. Hoping that I can get out to a few different spots this summer but I still hit the local parks just to stay in practice.

 

[Nancy-IL]

Glad to hear you're doing good. Hopefully you'll find a honey hole and you'll be rewarded for your efforts. I'll be keeping my fingers crossed for you. Take care and HH, Nancy