Conductive Carbon Fiber Lower Rods

[RONS DETECTORS MINELAB]

The GPX-5000 lower shaft has no carbon and also has a plastic end piece that would be great if someone could make a printed 8” section to fit onto the lower section of any carbon shaft. The 6000 can also hear it’s own carbon shaft when shaft is put directly under the coil.

JP even had non metal upper shaft’s for using larger GPX coils, that why I buy Doc’s upper carbon shafts now.

Doc’s fiberglass long rod for the GPX fits into the upper shaft of the Equinox/Manticore as seen in the picture if anyone has one of these and want to do some testing to see if sensitivity is lost as this shaft also  is non carbon fiber but very heavy.

Notice Coiltek’s end piece on Doc’s fiberglass rods are Gorilla glued in so if Trevor from Coiltek could make these 8” or more we could glue in a carbon shaft as I believe that is all we would need to get far enough away from the coil.

My GB2 screams and even discriminates on all carbon fiber shafts and on wildfire caused burned out roots and stumps. 
 

In the top picture I like how Minelab has a short piece of plastic to separate the shaft from the coil even though the legacy shafts were non conductive.

[steveg]

Hi all,

I wanted to chime in here.  Yes, carbon-fiber is electrically conductive.  A carbon-fiber tube is MUCH less conductive than a metal tube, but -- certainly carbon fiber does conduct electricity.  All carbon-fiber tubes will sound off, with a pinpointer.  I've never seen or known of one that doesn't.  Carbon-fiber tubes are produced by a relatively small number of factories, and the raw materials (carbon-fiber fabric) are produced by an even smaller number of companies -- so, while I have obviously not tested all carbon tubes, from all factories, I am fairly confident in stating that "all" carbon tubes are conductive, and thus all would be detected by a pinpointer.

WITH THAT SAID, the question is whether this is an issue, for detecting.  Is this something that affects the performance of the detector?

I looked into this question years ago, and concluded, based on my sources, that it is NOT an issue, to any appreciable degree.  But, since this has suddenly become an topic of interest, I wanted to address it in as scientific of a way as possible, and since I'm not an electrical engineer or detector designer, I decided to have an detailed conversation with someone who is -- Tom Dankowski (NASA Engineer, and also a integral part of Minelab's engineering team, on the Manticore project).

I called Tom a couple of weeks ago, and we spoke at length on this subject.  The short version of the story is that Minelab IS aware that carbon fiber is detectable, and yet they have concluded through rigorous testing that it is of essentially no issue, with respect to the performance of detectors -- even the highly sensitive Manticore.

To elaborate...

FIRST, as has been discussed here, the shaft is not "in motion" relative to the coil (except during the second or so where you may be setting the machine down and bending the coil flat -- thus momentarily putting the coil and lower rod "in motion" relative to each other).  AND SO, for a VLF-IB machine, the shaft is not "detected" -- it won't "beep" in other words, given the lack of motion relative to the coil.  BUT -- the other issue to consider is that even an object that is not "in motion" relative to the coil, can have an effect on the electromagnetic "footprint," or "envelope," surrounding the coil.  In a worst-case scenario, with a highly conductive metal object (say, a copper disc) sitting on, or very near, the coil, this object, while not "detected," will "alter" the electromagnetic "lines of flux" that surround the coil.  In a worst-case scenario, with a highly conductive object very close to the coil, a "weakness" in detectability in some portion of the coil's footprint can occur.  In other words, there could be a location within the coil's footprint where there is a relative "null," or "weakness" in terms of target detectability.  So -- that's the question at hand...i.e. is a carbon-fiber tube able to "affect" or "distort" or "alter" the electromagnetic field, to a degree and in a way that might reduce "sensitivity" of the coil at some location or sector beneath the coil.

This was what Tom and I discussed at length.  He noted that Minelab was attuned to this possibility, and thus they needed to test/evaluate to be sure it would not be an issue.  Tom assured me that this was tested very throughly (use of carbon shafts on the Manticore, during the design phase of the Manticore platform).  Obviously, carbon tubes are much less conductive, from a "detecting" perspective, than, say, an aluminum tube.  As such, a carbon tube would clearly have MUCH less effect on the electromagnetic field surrounding the coil.  But still, it is something that Minelab needed to be sure was no more than negligible, at worst, if they were to ultimately decide to utilize carbon fiber for the Manticore shaft.  He said that based on their thorough testing -- which included evaulations with an oscilloscope that they performed so as to truly "see" any effect of the carbon tube on the electromagnetic field surrounding the coil -- they found that the effect of the carbon tube on the coil's electromagnetic field was so small/negligible, as to be considered an entire non-issue.  This is why they were comfortable proceeding with the utilization of the carbon-fiber shaft.  He said that for all intents and purposes, the carbon tube can be considered to have "no" effect...

He also let me know that this was important to them to be sure of -- in that clearly some of Minelab's competitors do not use carbon-fiber shafts.  And so, given how competitive things currently are between the top detecting companies, to produce very high-performance machines, Minelab COULD NOT AFFORD to do something that would "cripple" or "handicap" in any way, the performance of the Manticore (or EQX 700/900) RELATIVE TO the performance of their competitors' top-end machines.  And so, this is something they were VERY cognizant of, and thus tested thoroughly.  And again, he assured me that based on their testing, it is for all intents and purposes a complete non-issue.  They were prepared, if testing warranted it, to use a different lower rod material (obviously they did, with the lower rod on the otherwise aluminum Equinox 600/800 shaft, as they knew that an aluminum lower rod WOULD HAVE had a negative effect on the coil), but since testing with carbon fiber, during Manticore design, showed that any effect was negligble at best, they were therefore fully confident in proceeding with carbon fiber.

One other point I will make is, there is also a similar consideration with the fact that we have a copper wire (coil cable) that also, by definition, lies within the electromagnetic footprint of the coil.  And that, too, would have a small, but can-be-considered-negligible effect on the electromagnetic field surrounding the coil.  Obviously, if you touch the coil cable with your pinpointer, you'll detect it, as well.  But, again, the effect is negligible and therefore not an issue that we concern ourselves with.  It's the same way, with a carbon tube.  There is also the "connector" that Chase mentioned, where the coil cable connects to the coil, which would likely have a greater effect -- certainly more than the cable itself, and most certainly more than the carbon tube.  

Hopefully, this helps.  I was assured during my conversation with Tom that it would be wasted effort to search for another type of material, to make a "non-conductive" lower rod, due to how negligible/minimal the effect is of the carbon fiber, on the coil's EM footprint.  Minelab was confident in not using an alternative material, and he suggested that I could likewise be confident.  The essentially "zero" effect that they confirmed, via their scientific/lab testing, on detection capability of the coil, simply does not warrant any reason to switch to another material.

I hope this helps.  

Thanks,

Steve

[Jeff McClendon]

20 minutes ago, steveg said:

Hi all,

I wanted to chime in here.  Yes, carbon-fiber is electrically conductive.  A carbon-fiber tube is MUCH less conductive than a metal tube, but -- certainly carbon fiber does conduct electricity.  All carbon-fiber tubes will sound off, with a pinpointer.  I've never seen or known of one that doesn't.  Carbon-fiber tubes are produced by a relatively small number of factories, and the raw materials (carbon-fiber fabric) are produced by an even smaller number of companies -- so, while I have obviously not tested all carbon tubes, from all factories, I am fairly confident in stating that "all" carbon tubes are conductive, and thus all would be detected by a pinpointer.

WITH THAT SAID, the question is whether this is an issue, for detecting.  Is this something that affects the performance of the detector?

I looked into this question years ago, and concluded, based on my sources, that it is NOT an issue, to any appreciable degree.  But, since this has suddenly become an topic of interest, I wanted to address it in as scientific of a way as possible, and since I'm not an electrical engineer, I decided to have an detailed conversation with Tom Dankowski (NASA Engineer, and also a integral part of Minelab's engineering team, on the Manticore project).

I called Tom a couple of weeks ago, and we spoke at length on this subject.  The short version of the story is that Minelab IS aware that carbon fiber is detectable, and yet they have concluded through rigorous testing that it is of essentially no issue, with respect to the performance of detectors -- even the highly sensitive Manticore.

To elaborate...

FIRST, as has been discussed here, the shaft is not "in motion" relative to the coil, and so, for a VLF-IB machine, the shaft is not "detected" -- it won't "beep" in other words, given the lack of motion relative to the coil.  BUT -- the other issue to consider is that even an object that is not "in motion" relative to the coil, can have an effect on the electromagnetic "footprint," or "envelope," surrounding the coil.  In a worst-case scenario, with a highly conductive metal object (say, a copper disc) sitting on, or very near, the coil, this object --while not "detected" will "alter" the electromagnetic "lines of flux" that surround the coil.  In a worst-case scenario, with a highly conductive object very close to the coil, this can result in a "weakness" in detectability in some portion of the coil's footprint can occur.  In other words, there could be a location within the coil's footprint where there is a relative "null," or "weakness" in terms of target detectability.  So -- that's the question at hand...i.e. is a carbon-fiber tube able to "affect" or "distort" or "alter" the electromagnetic field, to a degree and in a way that might reduce "sensitivity" of the coil at some location or sector beneath the coil.

This was what Tom and I discussed at length.  He noted that Minelab was attuned to this possibility, and thus they needed to test/evaluate to be sure it would not be an issue.  Tom assured me that this was tested very throughly (use of carbon shafts on the Manticore, during the design phase of the Manticore platform).  Obviously, carbon tubes are much less conductive, from a "detecting" perspective, than, say, an aluminum tube.  As such, a carbon tube would clearly have MUCH less effect on the electromagnetic field surrounding the coil.  But still, it is something that Minelab needed to be sure no more than negligible, at worst, if they would ultimately decide to utilize carbon fiber for the Manticore shaft.  He said that based on their thorough testing -- which included evaulations with an oscilloscope that they performed so as to truly "see" any effect of the carbon tube on the electromagnetic field surrounding the coil -- they found that the effect of the carbon tube on the coil's electromagnetic field was so small/negligible, as to be considered an entire non-issue.  This is why they were comfortable proceeding with the utilization of the carbon-fiber shaft.  He said that for all intents and purposes, the carbon tube can be considered to have "no" effect...

He also let me know that this was important to them to be sure of -- in that clearly some of Minelab's competitors do not use carbon-fiber shafts.  And so, given how competitive things currently are between the top detecting companies, to produce very high-performance machines, Minelab COULD NOT AFFORD to do something that would "cripple" or "handicap" in any way, the performance of the Manticore (or EQX 700/900) RELATIVE TO the performance of their competitors' top-end machines.  And so, this is something they were VERY cognizant of, and thus tested thoroughly.  And again, he assured me that based on their testing, it is for all intents and purposes a complete non-issue.  They were prepared, if testing warranted it, to use a different lower rod material (obviously they did, with the lower rod on the otherwise aluminum Equinox 600/800 shaft, as they knew that an aluminum lower rod WOULD HAVE had a negative effect on the coil), but since testing with carbon fiber, during Manticore design, showed that any effect was negligble at best, they were therefore fully confident in proceeding with carbon fiber.

One other point I will make is, there is also a similar consideration with the fact that we have a copper wire (coil cable) that also, by definition, lies within the electromagnetic footprint of the coil.  And that, too, would have a small, but can-be-considered-negligible effect on the electromagnetic field surrounding the coil.  Obviously, if you touch the coil cable with your pinpointer, you'll detect it, as well.  But, again, the effect is negligible and therefore not an issue that we concern ourselves with.  It's the same way, with a carbon tube.

Hopefully, this helps.  I was assured during my conversation with Tom that it would be wasted effort to search for another type of material, to make a "non-conductive" lower rod, due to how negligible/minimal the effect is of the carbon fiber, on the coil's EM footprint.  Minelab was confident in not using an alternative material, and he suggested that I could likewise be confident.  The essentially "zero" effect that they confirmed, via their scientific/lab testing, on detection capability of the coil, simply does not warrant any reason to switch to another material.

I hope this helps.  

Thanks,

Steve

Did you watch Bill Southern's video above? What it shows is definitely an "issue" no matter what Tom D says.

Gold prospecting capable detectors like the Manticore are super sensitive when using their gold prospecting modes. I doubt that Tom D. or Minelab did extensive testing on the situation that Bill accidentally videoed while he was trying out the Manticore in a perfectly normal, real life prospecting scenario. I can hear the coil/shaft sounding off even when Bill lightly sweeps his scoop against the coil with the heel of the coil over an inch away from the shaft.

My Manticore with M8 coil does exactly the same thing that the video demonstrated.

For larger target recovery, I have no concerns with using the Manticore's or any other carbon fiber shaft system as long as I am not detecting with the coil actually touching the shaft or in close proximity to it.

However, any kind of coil bump sensitivity, especially that which is caused by the shaft itself can make gold prospecting for sub gram targets on already hot ground that much more difficult. The type of sub gram target recovery that Bill demonstrated is totally normal for gold prospectors whether they are using a plastic scoop or their hand. Being able to rapidly locate these tiny targets in a cup full of hot dirt after digging them is really important to gold prospectors. Having all of that extra noise demonstrated in the video.......that is super frustrating and just not OK.

[palzynski]

I did not notice any depth change on my bed tests using a carbon vs a plastic lower shafts . Moderately mineralized soil .

This includes the XP goldmaxx ,  deus1 , deus2 , Vanquish 340 , Vanquish 540 , Equinox 800 etc .. A 10g coin is detected at around 11 inches either the lower shaft is made of carbon or plastic , this for a 11" coil size .

However yes a pinpointer will beep if too close from a carbon component , example a carbon lower shaft . This is why my detector is always at least 1m away when I use my pinpointer 

[Steve Herschbach]

28 minutes ago, steveg said:

Hi all,

I wanted to chime in here. 

I hope this helps.  

Thanks,

Steve

I wanted you too also so I posted the link here for you. As a marketing expert I can tell you belief overrides science and facts in this country. Nugget hunters will believe this is an issue because they have been told it is for 20 years. Plus, they actually see interference occur - see video above. Anyone in the know with a GP or GPX and large coils ran a full non-conductive rod, no watch, no metal boots, etc. Bottom line is you can look into making non-conductive shafts for the people that want them, or somebody else will, or people will make them for themselves. I say that as a person being in the camp that says it really is not hurting in most cases. But if it hurts in any case for any person anywhere, that’s enough to fuel this fire. Tom D knows nothing about nugget detecting so is a poor choice to quote here as an expert on the subject. He is the go to guy for white sand Florida beaches but bad ground, nuggets, I’ll listen to JP or Jeff or Gerry or Andy first.

[steveg]

Jeff,

I want to note that I do not want to get into any debates or arguments with anyone, that's not my intent.  I only wanted to share what I was told regarding this topic, by someone I trust, who is a person who would definitely know the answer to this question, from a scientific perspective.

But, I'll address your post, since you specifically asked me.  Yes, I watched the video.  First of all, I would like to note that obviously, he detected the object when it was in the ground, with no problem.  This is important to remember.  Look at all of the finds that all of us make, with this machine...it's obviously doing a great job, carbon-fiber and all.  That's not to say that if we can improve detectability or sensitivity, that we shouldn't seek to do so.  BUT -- it's also important to note that finding tiny gold with the Manticore DOES SHOW that it is performing quite well, right?  So that is one thing to note.

Second, yes -- the coil seems to detect the shaft when it is bent all the way flat (I say "seems to," because it could also be detecting the coil cable).  Anyway, note that it doesn't detect it otherwise.  In other words, the carbon fiber has to be VERY CLOSE to the coil, to be detected, confirming that while the lower rod is conductive, it is only rather weakly so.  I only point that out to confirm that this is a different scenario than using, say, an aluminum lower rod, which would be detectable at a much greater distance.

Thirdly, note also that the machine was only "chirping" when he was in the process of bending the coil, and then when the machine was being "moved" and/or "bumped" (slight motion of the coil relative to the lower rod, as it was lying on the rocks, and he was touching it -- such that the coil was moving slightly, as he moved the machine).  When he "let go" of the machine, and it was sitting still, even with the coil bent flat, the "detection" stopped.  Again -- no motion, no detection.  Finally, I should also note that when bent flat, the coil was also essentially "touching" the COIL CABLE.  And electricity flowing through the cable produces ITS OWN electromagnetic field.  That electromagnetic field is very likely ALSO something that has an effect on the coil -- it would be a tiny source of "EMI" so to speak, unless I am mistaken.  I can confirm this, if I need to do so.  But my point is, "chatter" would also be possible, if you lay the machine onto ANY cable that is conducting electricity.  Set your machine down above any buried electric wire or cable, and see what happens.  It seems just as likely to me that it was at least in part the COIL CABLE that was causing some of that, as it was the carbon tube.

Finally, I am not going to try to defend "what Tom D. says;" you are of course free to accept the information he shared, or reject it.  I'm certainly not here to tell anyone what to do or not do.  And likewise, you are of course free to "doubt" whether Tom/Minelab did in fact perform the necessary testing.  I'm only telling you that he told me specifically that they did, and it logically makes sense that they would have.  But, just note that you are essentially saying that Tom was dishonest with me, in your opinion.  I can only say that I trust Tom 100%.  He has never lied to me, and I'm unaware of him lying to anyone else.  I trust that what he told me is honest, and correct.

Thanks,

Steve

 

[Jeff McClendon]

Steve G, I am definitely not here to argue with anyone.

I just showed in the video and from my own personal experience that the thoroughness of Tom D. and Minelab's testing on the Manticore is at question, not their honesty. The same goes for Nokta since something similar happens with the Legend to a lesser extent.

If we all had similar occurrences of the coil detecting CF shafts during coin/jewelry/relic detecting target recovery similar to the normal type of gold prospecting target recovery procedures shown in the video, there would be an uproar.

Most people simply don't need to use that type of target recovery and they rarely lay their coils down flat like we gold prospectors do especially when trying to recover really small targets. The vast majority of users that detect with these gold prospecting capable Swiss Army knife detectors don't use their gold prospecting mode either.

That shotgun pellet in Bill's video was of the medium to large size and really easy to detect using the Manticore's gold prospecting mode. A #7 or smaller shotgun pellet or a 0.1 gram or smaller nugget is a real challenge to hear especially when the coil is detecting the shaft and making extra, unwanted noise. Getting ones hand or scoop as close as possible to the coil or actually scraping the coil is essential but it causes vibration and in the case of the Manticore and other gold prospecting VLFs with CF shafts, potential unwanted noise that can make the actual target if it is in the scoop or hand harder to hear and can mimic a target if the actual target is not in the scoop or hand.

 

[steveg]

14 minutes ago, Steve Herschbach said:

I wanted you too also so I posted the link here for you. As a marketing expert I can tell you belief overrides science and facts in this country. Nugget hunters will believe this is an issue because they have been told it is for 20 years. Plus, they actually see interference occur - see video above. Anyone in the know with a GP or GPX and large coils ran a full non-conductive rod, no watch, no metal boots, etc. Bottom line is you can look into making non-conductive shafts for the people that want them, or somebody else will, or people will make them for themselves. I say that as a person being in the camp that says it really is not hurting in most cases. But if it hurts in any case for any person anywhere, that’s enough to fuel this fire. Tom D knows nothing about nugget detecting so is a poor choice to quote here as an expert on the subject. He is the go to guy for white sand Florida beaches but bad ground, nuggets, I’ll listen to JP or Jeff or Gerry or Andy first.

Steve -- 

There is no doubt that Tom doesn't have the nugget detecting experience of you, or anyone else that you mentioned.  And experience is certainly an important thing.  BUT, I also don't think that means he is not qualified to comment, as he does have access to an expert level of knowledge of electricity and physics, and to the equipment that should offer scientific confirmation.  In other words, I don't think that subjective thoughts from ANYONE, on any subject, should automatically trump physics/science, and true scientific testing. 

If the electromagnetic field of a coil, in the presence of carbon fiber, is tested, using proper equipment such as an oscilloscope, and the result shows that the electromagnetic field is not altered to any appreciable degree -- and since it is THAT ELECTROMAGNETIC FIELD that directly determines detection capability -- then I think it is valid, from a scientific perspective, to conclude that detecting would not be affected.  I mean zero disrespect to anyone who is of the mindset that it DOES affect detecting.  All I can say is that I, too, am a scientist (though not an electrical engineer), and I have seen over the course of my career people who are ABSOLUTELY CONVINCED of things, that they strongly feel that they have figured out the reason for, such that no amount of proof, or scientific testing, or anything else, will ever convince them otherwise.  And you know what?  To some degree, I can respect the baseline skepticism.  I think skepticism and such are extremely important.  I am a very skeptical person myself, and critical thinking skills are SO important for all of us to develop/utilize/exercise.  But, at the same time, there has to be a baseline, that is based on good/proper testing, right?  In other words, speaking for myself, if someone wanted me to believe that carbon fiber may affect detectability of a small nugget, and given that I have serious doubts in that regard, then I would require (in order for my mind to be changed), that the person trying to convince me would show me their testing, their methodology, and then let me run the same tests myself, where I can control the variables, so as to see for myself if I can replicate their results.  If I can replicate the results, and see/measure the detrimental effects, then I would change my views.  I ALWAYS seek the truth; truth is very important to me.  But, arriving at truth requires care, and good/solid critical thinking and testing, in my opinion.  I would love to see some scientific testing that might show carbon fiber having a detrimental effect on small gold detection.  I have offered some scientific testing that says otherwise.  Is there something that someone can offer that would prove to be a solid counterargument?

Steve

[Steve Herschbach]

5 minutes ago, steveg said:

Steve -- 

There is no doubt that Tom doesn't have the nugget detecting experience of you, or anyone else that you mentioned.  And experience is certainly an important thing.  BUT, I also don't think that means he is not qualified to comment, as he does have access to an expert level of knowledge of electricity and physics, and to the equipment that should offer scientific confirmation.  In other words, I don't think that subjective thoughts from ANYONE, on any subject, should automatically trump physics/science, and true scientific testing. 

If the electromagnetic field of a coil, in the presence of carbon fiber, is tested, using proper equipment such as an oscilloscope, and the result shows that the electromagnetic field is not altered to any appreciable degree -- and since it is THAT ELECTROMAGNETIC FIELD that directly determines detection capability -- then I think it is valid, from a scientific perspective, to conclude that detecting would not be affected.  I mean zero disrespect to anyone who is of the mindset that it DOES affect detecting.  All I can say is that I, too, am a scientist (though not an electrical engineer), and I have seen over the course of my career people who are ABSOLUTELY CONVINCED of things, that they strongly feel that they have figured out the reason for, such that no amount of proof, or scientific testing, or anything else, will ever convince them otherwise.  And you know what?  To some degree, I can respect the baseline skepticism.  I think skepticism and such are extremely important.  I am a very skeptical person myself, and critical thinking skills are SO important for all of us to develop/utilize/exercise.  But, at the same time, there has to be a baseline, that is based on good/proper testing, right?  In other words, speaking for myself, if someone wanted me to believe that carbon fiber may affect detectability of a small nugget, and given that I have serious doubts in that regard, then I would require (in order for my mind to be changed), that the person trying to convince me would show me their testing, their methodology, and then let me run the same tests myself, where I can control the variables, so as to see for myself if I can replicate their results.  If I can replicate the results, and see/measure the detrimental effects, then I would change my views.  I ALWAYS seek the truth; truth is very important to me.  But, arriving at truth requires care, and good/solid critical thinking and testing, in my opinion.  I would love to see some scientific testing that might show carbon fiber having a detrimental effect on small gold detection.  I have offered some scientific testing that says otherwise.  Is there something that someone can offer that would prove to be a solid counterargument?

Steve

I never said Tom could not comment or that you could not quote him. I was just trying to help you as I have done here since day one. Good luck with your approach, I’ll leave you to it.