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Question About Ace 350 Shaft Being Too Close To Coil

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I have been playing with my Garrett Euroace (Ace 350) for the past couple of days, working it out and learning the machine to teach my daughter how to use it.  I was air testing some modern coinage to see what notches on the target ID scale they come up as so I could set up her discrimination. I got lazy and started waving them on the detector side of the coil, I noticed I was able to detect the coins all the way up to past where the shaft changes from plastic to metal, this is at 40cm, 15.7 inches in the old digits, this was with the coil straight too so when it's tilted it's even closer to the metal part of the shaft.

This means the coil is obviously seeing the metal shaft, if the coil is moving such as adjusting it's tilt I noticed the detector gets a target in when in all metal, if I use my heavy coin discrimination pattern it doesn't false when the coil moves.  I was wondering why this was falsing when the coil moves was happening yesterday until today when I was able to duplicate it when I discovered by accident I could detect coins past where the shaft changes to metal, it's the coil picking up the metal shaft!!! If I move the coil with it sitting on my table, even the slightest bit it rings off on the shaft! 

I realize I've not got the stock coil on there and the Nel Tornado is known as a deep coil but this is now a problem for me and the only solution I can think of is to notch out the discrimination point where the shaft sits so it can't see it, but then it may miss good targets in that range too.

I don't want to put the stock coil back on it, the stock coil wasn't too great and I really like this Tornado coil.

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Are there aftermarket shafts for Garrett that have a longer lower shaft? or is there some shaft from another detector I could mount it on that is longer in the plastic part?  I'm not a big fan of the shaft anyway, it doesn't even have Cam locks so a replacement shaft wouldn't be such a bad option.

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Here is a quick video showing a coin detecting past the shaft change over point, the amazing thing is the Target ID for the coin is bang on where it should be even at that depth.

 

 

Any help with this one would be appreciated as I've now given the detector to my daughter who decided she likes detecting now (finally) as she has a yellow bumble bee looking detector that can discriminate virtually everything out except our gold coins ?

 

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Yes, if the coil moves against the shaft, it can produce false signals ... if the coil has a sufficiently long range ... "You can use a camlock to remove the free movement of the coil, or you can use a long lower shaft .., I made a few measurements of my Ace 400. Perhaps it will help you...the bottom of the Garrett bar has a diameter of 20.0-20.15mm and a length of 50cm. You can use the bottom rod from the Equinox minelab 60cm... or other 20mm Rod...

november 3 iphone 5S 2018 003_DxO.jpg

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Perfect, so I just need a Ace 400 lower rod which they've made longer than the 350 lower rod probably for my exact problem, i guess when they made the Ace 350 they never expected coils to go so deep. I guess it might be easier to get an Equinox lower Rod, thanks very much! Very helpful.

 

 

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you can only get camlock, and adjust the bar from ACE 350 ..

November 4 iphone 5S 2018 001_DxO.jpg

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Thanks, I'll try find somewhere selling Cam locks then ?

 

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Perhaps you could put a dab of epoxy on the button of the camlock to make it go tighter.

You can see now why I made my shaft out of Kevlar.

I tread lightly because so many use Carbon fiber right to the coil and even using clunky metal cam locks now, to each his own. I feel like I am going to have to preemptively defend myself, but I will remind others that I am entitled to follow the form follows function mantra just as they are entitled to use metal coil bolt like in the old days.

Does it matter? When we are talking about finding treasure, how would you ever know?

Here is what you can do to test it.

1. Test a coin for depth, let's say it goes to 12"

2. Place a beer can beside coil and repeat step 1.

The result is you can't see the coin at all!

At the very least placing more metal near your coil is going to negatively affect your depth and sensitivity to small items.

Interesting conversation, thanks for sharing.

 

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Alluminati ....We also try to eliminate any metal that is within reach of the coil by using the lower carbon rod - the result is also weight loss, improved equilibrium and also the stiffness of the detector. Yes aramid-Kevlar also stands behind the idea...

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EL NINO77, do you have a piece of carbon rod handy that you can put a silver coin inside of the tube and see what happens when you try to detect it?

I don't have anything nearby that I can think of that is carbon fiber.

If you can still detect the coin inside the tube to your satisfaction, then you should be alright. If the coin disappears then you have problem.

Carbon fiber is electrically conductive, you can induce a electrical current through it in a magnetic field. In water, particularly salt water you may experience galvanic corrosion if metal parts are not isolated from it. 

How conductive it is will depend on your particular tube, how much of it is resin, how long are the fibers and how they are oriented.
You may note that on the CTX, ETrac, Anderson shaft etc they have plastic for the last 4"-6" of their carbon shaft. This gets the carbon well up and almost behind the coil. I suspect this is about the practical limit for that particular sized, 11" coil. With a smaller coil you could probably go a little closer with carbon. 

For comparison, I have a detector here from 1985 with a 8" coil and an aluminum lower shaft. It has a 4" plastic yoke attached towards the rear of the coil with a plastic bolt.  It looks like good rule of thumb would be to keep any conductive rod at least half your coil diameter away, keep it out of the radius of your coil.

Conversely, Kevlar is a synthesized polyamide similar to wool and silk. It is organic, transparent to radio waves making it the preferred choice in applications like this.

 

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the truth of the carbon composite can affect the working coils, on my carbon rod equinox  I have a plastic ABS head. My first modified detector had a glass fiber rod.

sony sola 1073 (600 x 337).jpg

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