Shaft question

[Anonymous]

I just have a question if I may regarding the length of the non-metallic
lower stem on detectors (SDs in particular) Being that the upper stem is
metal does a person that has to run with the plastic shaft adjusted shorter
sacrifice in performance of the detector due to being a couple inches closer
to the metal stem with the coil. These stems are all made adjustable, but to
a layman in electronics it seems shortening the plastic stem at all would
interfere somewhat?? This is probably a dumb question, but how else is one
to learn?
Bill

 

[Anonymous]

Bill, in general that's not something one needs to be concerned about. There could be a problem if you ran it with the plastic shaft so short that the searchcoil was close to the metal part of the metal detector, or if you were swinging so vigorously that the whole assembly were flexing.
--Dave J.

 

[Anonymous]

Bill
I have just finished testing a newly introduced PI detector for a local manufacture. This manufacture uses a metal lower rod on their unit. The question arose as to does the metal lower rod affect the performance of the unit. I outfitted a couple of units with fiber lower rods along with their metal rod. I could find no noticeable change in the performance of the units with the fiber rods installed. Yes the detector knew the metal rod came close to the coil when connecting by a increase of the threshold, but it settled right down, and performed just fine. With either rod the detector had no problem detecting a US nickel at over 15". I also could see no change to it

 

[Anonymous]

HI Bill
I had the same concern as you and spent a fair bit of time in constructing a full plastic and fiberglass intermediate shaft for use with the big Minelab coils but discovered that there was no discernible difference over the metal intermediate shaft provided there was no flexing of the coil in relation to the metal shaft and control box.
However, having said that there is no difference Coiltek have available a full length fiberglass shaft that is supposed to quiten down any noisy coil. I have considered buying one but would like to try one first to see if there is in fact any improvement.
Cheers
Steve D

 

[Anonymous]

Hi Steve,
I was trying to keep it short in my last response. Flexing does play a part in the equation. The units in question have a very flimsy coil to lower rod clevis. Snapping the sweep fast with this flimsy clevis can create some noise. Slow down a bit and it goes away. I wouldn

 

[Anonymous]

Thanks All for your response to my question.
Bill S.