Wiggle pinpointing and deep holes!

[thedayawaits]

I took my new Quattro out to an 1800s schoolhouse the other week for its first real run since I had it. The site was clean and trash-free. As I approached the building, nothing registered, but once I got near the stone stairs near the entrance, the machine went crazy with deep targets (the ground used to be lower there, and it seems like the lower ground was lined with gravel when the schoolhouse operated because my deeper holes all hit gravel). I dug several holes but seemed to have some trouble pinpointing with deeper objects. I found a single piece of 1979 clad easy at 3-4 inches, but the deeper targets gave me real trouble. With one object, I got a strong, repeating penny signal at 8 inches or so (bottom third of the meter) and used the leche digger to get down there. I dug about as far as I could reach, deeper than the hilt of the digger, and still the coin seemed to be just beyond the bottom. I hit gravel. Finally it got dark and I just filled the plug. Other times, the target would seem deep, I would use the wiggle method to pinpoint, and I would dig the hole, and then re-wiggle and it would seem like the target had moved a few inches.
Any insight into these things?

 

[TomH]

thedayawaits,

The only problem that I have had with pinpointing is with cut nails. It seems that a really rusty nail can result in a "wandering target" like you described. So far, all the good targets that I have found are dead on when pinpointing. I have gotten to the point that if a signal "moves" when I am pinpointing I just fill in the hole because I know I am going to find another nail.

BTW: Rusty nails that have a curve to them can sound off just like a bullet on my Safari. Strong 32/34 with a nice flutey tone.

TomH

 

[ohio fred]

Though i don't have a minelab, but i find with my detectors the same problem in the same situation.What happens i finally find it off to the side even if it is a coin or junk sometimes i believe the signal is bouncing around from deposited in the gravel or the ground on times like those i wish i had a hand held pin pointer.

 

[hershey1]

Sounds like a nail my friend. Have you tried turning 90 degrees and pin pointing again? You can always dig it, but it sure sounds like a nail.HH

 

[thedayawaits]

Tom and Hershey, I think you've nailed it. I dug one old, rusty flat head nail and my buddy said that they had been probably used on the slate roof. The question is, how to tell the difference between a rusty nail eight inches down, and a penny?

 

[bigolhorns]

Always turn 90 when pinpointing. Coins,even deep ones,don't move.... ever. Nails and small diameter wire always move.

 

[ronaldj2]

Worms move, I don't imagine that while you're in the midst of pinpointing that nails and wire are gonna move so much as to throw off the target. Please don't misconstrue this as a criticism, but clarification is needed when making a statement like that. Are you saying that the longer the item is in the ground the more it moves ? If I find a coin at 8", does that mean it started out at 8" deep? I know that when corrosive metals (nails, wire) as they age they oxidize or rust. The rusting can produce what is called a halo effect. Which is basically a rusty leach field around the items. Does this make sense?
Have you ever found a penny or a nickle that is corroded ? When you pick up the coin, the imprint is still there in the ground, and sometimes it looks like another coin is there. This is a halo effect, rust or corrosion is left behind. Now try waving you detector over the halo spot, what happens? Usually nothing, unless there was a very large amount of corrosion, and even then it is still distinguishable between the coin and the halo. My only purpose is good thought provoking posts. Thank you bigolhorns for making me use my noggin. By the way, this is not a scientific answer nor am I a scientist. I am just an average guy who likes to detect, and maybe write down a few thoughts about things. My children and I have purposely dropped coins in our yard and one or two yrs later we detected them 2-6 inches deep. We also have 4 seasons with extreme changes in the ground. The ground can go from dry to wet or frozen to thawed or vice versa. Items can become part of the earth rather quickly. Other regions of the country (USA) may not get these ground changes and items may not end up as deep or as corroded. Or just the opposite. Sorry all, for such a long post. I hope to get many responses to this good or bad it doesn't matter to me. I am definitely not the last word on any subject and can certainly handle correction. Ron

 

[TomH]

Ron,

I don't think that anyone is saying that the target actually moves, just that there is something about the halo of a rusty old nail that causes the signal to vary. I'm not a coin hunter but hunt relics and have had this happen uncountable times. You get a signal, pinpoint and start digging the hole. About six inches down you re-pinpoint and it now says that the target is as much as six inches away from the original spot. At that point, in the vast majority of cases, if you carefully work the edges of the hole you will find a rusty square nail. I don't know why this happens, only that it really does happen. And the phenominon is not restricted to Minelab machines, I have had friends say the same about the Fisher F75 and the Whites MXT. It seems to happen more when the soil is moist and the nail is really corroded.

TomH

 

[bigolhorns]

Your kidding right!!!!! You didn't really think we were saying targets were actually moving in the ground did you????????

Worms move, I don't imagine that while you're in the midst of pinpointing that nails and wire are gonna move so much as to throw off the target. Please don't misconstrue this as a criticism, but clarification is needed when making a statement like that. Are you saying that the longer the item is in the ground the more it moves ? If I find a coin at 8", does that mean it started out at 8" deep? I know that when corrosive metals (nails, wire) as they age they oxidize or rust. The rusting can produce what is called a halo effect. Which is basically a rusty leach field around the items. Does this make sense?
Have you ever found a penny or a nickle that is corroded ? When you pick up the coin, the imprint is still there in the ground, and sometimes it looks like another coin is there. This is a halo effect, rust or corrosion is left behind. Now try waving you detector over the halo spot, what happens? Usually nothing, unless there was a very large amount of corrosion, and even then it is still distinguishable between the coin and the halo. My only purpose is good thought provoking posts. Thank you bigolhorns for making me use my noggin. By the way, this is not a scientific answer nor am I a scientist. I am just an average guy who likes to detect, and maybe write down a few thoughts about things. My children and I have purposely dropped coins in our yard and one or two yrs later we detected them 2-6 inches deep. We also have 4 seasons with extreme changes in the ground. The ground can go from dry to wet or frozen to thawed or vice versa. Items can become part of the earth rather quickly. Other regions of the country (USA) may not get these ground changes and items may not end up as deep or as corroded. Or just the opposite. Sorry all, for such a long post. I hope to get many responses to this good or bad it doesn't matter to me. I am definitely not the last word on any subject and can certainly handle correction. Ron

 

[ronaldj2]

No I didn't really think you were saying targets were moving. Unless we are DWI detecting while intoxicated. What I did do was to provoke a post. Got one from TomH. Again wasn't trying to misconstrue or criticize. I have gotten different depth readings because of corrosion. Keep up the good posts. Ron

 

[hershey1]

That's it. For over 30 years of detecting I've been detecting while intoxicated. Just kidding. Great thread and forum.HH

 

[edjcox]

Remember what your doing

Your detector is emitting an EM field and it is penetrating the soil. As in penetrates it might encounter a metal object. That object absorbs some of the field and re resonates at a given frequency depending on your detector. Your detectors senses that re-resonation and your coil takes that signal into your processor and dtermines what to display. Now that old zinc penney lieing there for years has corroded and some of the metal has leached around the oject into the surrunding soil. Depennding on your detectors frequency and the intensity of your coils field that leached area of the soil may conduct some of the EM field and reresonate a ble signal. Because this leached soil is not actually metal it might create a phantom efect that is highly dependent upon the field strength and orientation ofthe

 

[edjcox]

Remember what your doing

Your detector is emitting an EM field and it is penetrating the soil. As it penetrates it might encounter a metal object. That object absorbs some of the field and re resonates at a given frequency depending on your detector. Your detectors senses that re-resonation and your coil takes that signal into your processor and determines what to display. Now that old zinc penny lieing there for years has corroded and some of the metal has leached around the oject into the surrunding soil. Depending on your detectors frequency and the intensity of your coils field that leached area of the soil may conduct some of the EM field and reresonate a detectable signal. Because this leached soil is not actually metal it might create a phantom effect that is highly dependent upon the field strength and orientation of the coil above it. Step a way swing past and that orientation shifts. The phantom return shifts as well. It's best to reorient and approach such a signal from several directions. If it's not solid and repeatable it may just be deep or may be a halo phantom.

I shy away from iffy signals. Probably miss soe goodies that way but it's my style. You need to do what you think is right.

 

[thedayawaits]

I'm in heaven learning from you all who have done this so much!! So, if I cross-save and use ferrous tones, I can avoid even having this quandary, right? Because I will be able to tell, at the bottom of the eight inch+ hole, whether it is an iron nail or a a non-ferrous coin or ring, etc... Or can the halo from old square nails also mess with ferrous tones?

 

[TomH]

thedayawaits,

I should have mentioned that I was using Ferrous tones when this phenominon happens. I almost never use the conductive tones because I like having the ferrous targets sound off lower tones than the non-ferrous.

TomH

 

[thedayawaits]

Strange. So the iron halo gives a highly conductive number frequency but a very ferrous sound. That should be a dead giveaway!

 

[TomH]

Actually, both the TID and the tone both indicate a lead target (32/34, high flutey tone).

In the few cases where the TID and tone do not agree I go with the tone and that seems to be correct every time.

TomH