coil bolt

[richbat]

was out yesterday and the nylon bolt broke on my coil of my bandido 2 u/max.so i replaced it with a stainless steel bolt with rubber washers,will this have any affect on the machine? i'm thinking it shouldn't, being that the bolt is stationary,any opinions?

 

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[steve from ohio]

There was a time when almost all detectors came with metal bolts holding the coil on. It has no effect,

Then why is it that all modern detectors no longer use metal bolts? Could it be that engineers have discovered that steel in a detectors field is not a good thing to have?

The engineers who designed the equipment specify nylon bolts. To me that means no metal in the EM field. The coil is nothing more than a transmitting and receiving antenna. Putting a piece of metal in the electromagnetic field will affect the ability of the machine.

Yes the coil will detect above it almost as good as below it....except to say that the ground is a better conductor of the electromagnetic field so it will operate better in the ground than the air in most instances.

Someone also posted that it did not affect his finds is incidental. I would guess that you did no scientific research into using a steel bolt in order to prove that it did not and would not.

I say go ahead and use the steel bolts if you want. It really does not matter to me one way or the other. If it was me, no way.

 

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[Tin Nugget]

There was a time when almost all detectors came with metal bolts holding the coil on. It has no effect,

Then why is it that all modern detectors no longer use metal bolts? Could it be that engineers have discovered that steel in a detectors field is not a good thing to have?

The engineers who designed the equipment specify nylon bolts. To me that means no metal in the EM field. The coil is nothing more than a transmitting and receiving antenna. Putting a piece of metal in the electromagnetic field will affect the ability of the machine.

Yes the coil will detect above it almost as good as below it....except to say that the ground is a better conductor of the electromagnetic field so it will operate better in the ground than the air in most instances.

Someone also posted that it did not affect his finds is incidental. I would guess that you did no scientific research into using a steel bolt in order to prove that it did not and would not.

I say go ahead and use the steel bolts if you want. It really does not matter to me one way or the other. If it was me, no way.

Because plastic held together with steel, swinging back and forth puts to much pressure on the plastic and can cause it to break. I know, Iv'e done it. I think Tesoro was about the last manufacturer to stop using metal bolts and it wasn't long ago. As far as research, it was already done by the manufacturers. The detecter can't detect it because it's moving with the coil. Try this, bury a coin say 8 inches down and work your detector to where it will barely pick it up, now change out the plastic bolt for metal one or just tape a metal washer to the top of the coil then resweep the coin. No change in the signal will occur. I did this along time ago with my Classic ID but it had nothing to do with the bolt. I used a rusty nail on the coil and a nickle target and the only reason I did it was because someone told me it would not affect it and I found it hard to believe. The nickle target gave the same response, no change at all. Heck if nothing else do some experimenting. Part of what makes this hobby fun.

 

[TORRERO]

Could it be that engineers have discovered that steel in a detectors field is not a good thing to have?

No of course not....
A plastic bolt is cheaper than a brass bolt any day....
That's what those Engineers learned....
How to get more of your money by giving you less.... Yipee !!!!

 

[steve from ohio]

Could it be that engineers have discovered that steel in a detectors field is not a good thing to have?

No of course not....
A plastic bolt is cheaper than a brass bolt any day....
That's what those Engineers learned....
How to get more of your money by giving you less.... Yipee !!!!

"The more metal you keep away from the coil of your detector the more sensitive the detector is. " According to the designers and builders of Coiltech coils directly from their web site.

And I can prove it.

Try metal detecting around the metal playground equipment with a large coil. Smaller coils work better around those things because their electromagnetic fields are smaller.....less concentrated. It has been my experience with my White's machines, my Minelabs and my Fishers, is that it is very difficult or almost impossible to detect around metal objecs because of interference from the metal that is around them. It not only picks up the metal around them, it also weakens the field that the detector generates.

Heck. Do this.....instead of those flimsy plastic coil covers, try using an aluminum frying pan for a coil cover! After all it does not make a difference unless you are moving the coil........and the frying pan would not be moving.......if I use some of the logic some of you folks are using. And yes, the plastic coil cover would be cheaper for sure....that is why the engineers said to use it instead of an aluminum frying pan.

You see, they do not call it a metal detector for nothing!!!!!!

I'm not all that serious about this subject but it is kind of fun to think about it.

By the way....here is a diagram showing the effects of a metallic object to the electromagnetic field of a detector. In order for your detector to not see that bolt, it has to be discriminated out of the detectors field and so by doing that, you will be lessening the ability of the detector.

There is a reason why some folks never use discrimination and that reason is...........

They want to find that stainless steel bolt sitting on top of their coil of course!!!!!!!

 

[Frankn]

Here is something I forgot to mention in my earlier post. Make sure you are buying a NYLON bolt, not just a plastic bolt. The nylon will streatch rather than break. Of course, like all things, it has it limits too.

 

[silverswede]

If you believe metal won't detect on or over your coil then you should be able to detect under your car or truck and I've been missing some good spots.

 

[Tin Nugget]

If you believe metal won't detect on or over your coil then you should be able to detect under your car or truck and I've been missing some good spots.

The question or should I say debate is weather metal attatched to a coil and thus swings with the coil has any effect on the performance of the detector. We all agree the detector will not give a response to the metal. If you could attatch a car to the coil and swing it, again, no response.

 

[greydigger]

I'm thinking of attaching a large magnet to my coil to pick up those pesky nails.
Because the coil will be heavier maybe a rope from the front up to the handle will support it.
What is the VDI for stainless steel?

Grey

 

[Frankn]

This is getting to be fun! Greydigger: That would be iron &/or nickel depending on your detector's personal bias!

​

 

[richbat]

well,just spoke with tesoro on my problem with the coil bolt and was told by them the manufacture that a stainless steel bolt will not have any affect on my bandido 2 u/max. they did however offer to send me a new nylon bolt for it,they are absolutely great people to deal with, answered all my concerns and put my mind at ease.thanks tesoro you definately have my continued business.

 

[mts]

I disagree that it will not effect performance in all cases. There are certain detectors in which is most certainly WILL affect performance. It all depends on the detector and how it is tuned. Things like amplifier bias points can easily be affected by putting something metal (even if it is stationary) into the field of the coil. For example, a pulse induction metal detector will have a different operating point with a large piece of metal sitting directly inside the coil. If this operating point results in amplifier saturation then you will have a very hard time detecting anything at all. As a side note I have designed and built my own PI detector. I can tell you with 100% certainty that putting a metal bolt of any kind next to the coil of this unit will result in it not working unless I change the bias point by opening the unit and adjusting a potentiometer. But my detector is hardly a professionally designed unit.

Again, the world is not black and white. You will have to try it with your own detector to be sure. If the detector is made such that the operating/bias point is variable and can adapt to having a piece of metal next to the coil then you may see very little difference between a nylon and a stainless steel bolt. If your detector is not able to adapt to the difference then it may be rendered completely useless. You can't rely on individual data points from the members here who have tried it and had success. You need to simply try it yourself. If you are satisfied that it works then go for it. If you find that certain metals end up being masked out or you see a drop in depth then it is time to switch back to nylon.

As usual, the answer is: "it depends".

 

[Frankn]

Mts: Looks like you got this one right. I glad you agree with my prior post.

​

 

[lumbercamp]

Tin Nugget mentioned that detectors used to come with metal bolts. I dug out my Garrett Super Mini Hunter that I bought in 1972 and yes it does have an iron bolt and wing nut. I used that detector for almost 25 years and found numerous relics with it.

 

[scaupus]

Tesoro's did ship with stainless bolts. the change to nylon may have been for customer perception - I certainly noticed the stainless bolt and wondered about it when I bought my tesoro 2nd hand; or it may be to protect the plastic parts of the coil or clevis, but after using my tesoro with the SS bolt many times, I don't think it's to improve performance.

 

[Ism]

Concentric and DD coils are nulled at the factory for best performance. While the SS bolt will not affect the performance in a really significant manner, it will detune the precision factory coil null.
But the most important reason is its mechanical weak link. Like a circuit breaker protects your house wiring, its cheaper to replace the bolt than broken coil ears or the shaft end effector.

 

[cudamark]

No of course not....
A plastic bolt is cheaper than a brass bolt any day....
That's what those Engineers learned....
How to get more of your money by giving you less.... Yipee !!!!

Almost all the older detectors used metal lower shafts too, but the newer machines went to carbon fiber lower shafts for a reason, and it wasn't because of cheaper costs.