Odd Screw, Barely registers on my detector…

[Bob Blaylock]

So, a week or so ago, I was out with my metal detector, and I spot a bright, shiny screw on the ground. I run my metal detector over it, and it doesn't register at all. I picked it up, and took it home, and forgot about it until today.

Now, in my home, if I turn on my metal detector, and hold the screw in front of the coil, it just barely registers, very weakly. It's a cheap metal detector, I know, but never before have I encountered anything of this size, obviously made of metal, that doesn't register on it much more strongly than this screw does.

This screw is also very weakly magnetic. With a powerful magnet from a hard drive, I can just barely get enough force to support this screw's weight.



Obviously, this screw is made of some sort of metal, but what kind of metal could it be, and why would it register so weakly on my metal detector?

 

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[Bquamb]

HMMM, HAVE YOU COMPARED IT TO SIMILAR SCREWS, MATERIALS, ITEMS OF SIMILAR SIZE? HAVE YOU TRIED A BOBBY PIN?

(CAPS IS STUCK ON, EVEN ON REBOOT, SORRY!)

 

[Injunbro]

Probably Chinese pot metal.

 

[luvsdux]

Some detectors are designed to discriminate small iron etc. automatically unless the machine is set in all metal. Likewise, smaller targets often hit poorly even though composed of accepted metals. If your machine has an all metal setting, you might give that a try. Not all machines are designed with a totally full range of acceptance, especially in relation to small iron.
luvsdux

 

[Tuberale]

May be your detector, Bob.

 

[Rob.IV]

Probably Chinese pot metal.

Yes yes... I agree. Definitely made in China...!!!


Bloodiest Pirate of the Pull-Tabs...!!!

 

[Tom Slick]

Stainless steel

 

[Bob Blaylock]

Some detectors are designed to discriminate small iron etc. automatically unless the machine is set in all metal. Likewise, smaller targets often hit poorly even though composed of accepted metals. If your machine has an all metal setting, you might give that a try. Not all machines are designed with a totally full range of acceptance, especially in relation to small iron.
luvsdux

As I've said, it's a cheap detector. It does have an “Eliminator” knob, which I usually leave at the far-counterclockwise setting, which seems to be the setting to detect all metals. I've only ever experimented a few times with this knob, more or less confirming that at different settings, it becomes less sensitive to different metals. I've toyed with the idea of attempting to calibrate it, trying different kinds of metals, and marking the knob as to which kinds of metals it's most sensitive to at which settings.



The detector was set, as described, at the full-counterclockwise setting of that knob, when, in the field, it failed to respond to this screw on the ground, and, later, at home, when it only weakly responds to it. I have found that setting this knob at any other setting seems to cause it to not see this screw at all.

There must be some very complex set of stuff to know to understand why some things register more strongly on this detector than others. The size of the object doesn't always seem to have nearly as much to do with it as one would expect. I've had very small objects register very strongly, and larger objects not register all that strongly. This screw is the most extreme example that I've seen yet; barely registering, if it registers at all, even though it's reasonably-sized compared to other things that register quite well.

Here's that screw again, with a penny for scale, and a very small metal ring. I found that small ring buried several inches deep, and it registers very strongly on my detector, even though it's quite small.

 

[DiggerGal]

Is the screw titanium? It will not register if it is.

 

[Bob Blaylock]

Is the screw titanium? It will not register if it is.

I don't know. How can I tell?

Perhaps a titanium/iron alloy? It does register very weakly, and it is very weakly magnetic.

I don't have the means to objectively weigh it, and compare it with other objects of similar volume, but I think it seems just a bit lighter than I instinctively think it should be. I suppose that could also indicate titanium.

 

[dirtdigginfool]

Stainless steel

Yep...stainless...I thInk Tom nailed it...HIGHLY doubt it's titanium, it is a VERY expensive material, and I've never seen a common wood screw made from it... (sorry Diggergal-but good guess!)...I think it's actually a combination of the cheaper machine and the staimless steel. JMHO...ddf

 

[l.cutler]

Yup, stainless steel for sure.

 

[jadocs]

What is your power/sensitivity knob set at. Have you turned it all the way up to see if there is a difference?

 

[jadocs]

I just checked my detector and it is able to detect the titanium rods I have in my back

 

[cudamark]

Is the screw titanium? It will not register if it is.

Titanium registers just fine on any machine I've ever owned. I've found many titanium rings with them.

 

[jadocs]

Makes sense...my Garrett carrot doesn't pick up the hardware in my back though.

 

[Rawhide]

My ld garret picked up the metal in my arm just fine. But I would say you got a space shuttle screw there. Better contact nasa and return it promptly.

 

[Bob Blaylock]

What is your power/sensitivity knob set at. Have you turned it all the way up to see if there is a difference?

Yes, all the way up. That's how I nearly always set it.