Question on carbon fibre shafts for gpx 5000

Hello to all.
I've been detecting for a couple of years and as the topic suggests I have a question in relation to carbon fibre shafts for 5000's. I have the standard coils that came with the 5k and a couple of nugget finders ( 12 x 7 ellip. mono & 14 inch round mono ) both of which I am very happy with.
I am contemplating on the purchase of a NF 18'' round mono and after surfing the net some say that you should get either a carbon fibre or fibreglass shaft for your GPX or your large coil will get interference from the standard GPX shaft and reduce it effectiveness as a result.

Has anyone used or have a carbon fibre shaft or for that matter the otto ( now Sandy ) fibreglass version? Is it true that the larger coils do get interference from the standard GPX shaft?

Any thoughts / advice would be greatly appreciated as I do not want to invest in the wrong set up. Thanks.

Hi arr
just seen no one has answered your question.
I have tried both fibreglass and carbon shafts on my GPX's and cant say I have noticed much difference to the standard alloy . I use up to a 24 x 12 NF. The issue with big coils is more with a potential loss of sesitivity because of the metal in the shaft, rather than any " interference"    One problem I had was tight lower stems in the id of the new glass and carbon shafts. Would pay to check your stems will fit before purchase !!
Cheers
DB

Hi DB

Thanks for the heads up, I'll be sure to get onto it.

Cheers
aar

aar wrote:Hello to all.
I've been detecting for a couple of years and as the topic suggests I have a question in relation to carbon fibre shafts for 5000's. I have the standard coils that came with the 5k and a couple of nugget finders ( 12 x 7 ellip. mono & 14 inch round mono ) both of which I am very happy with.
I am contemplating on the purchase of a NF 18'' round mono and after surfing the net some say that you should get either a carbon fibre or fibreglass shaft for your GPX or your large coil will get interference from the standard GPX shaft and reduce it effectiveness as a result.

Has anyone used or have a carbon fibre shaft or for that matter the otto ( now Sandy ) fibreglass version? Is it true that the larger coils do get interference from the standard GPX shaft?

Any thoughts / advice would be greatly appreciated as I do not want to invest in the wrong set up. Thanks.

Hi aar,
Apologies for the late reply.

I remember quite a few years ago now, I asked a good mate of mine who definitely knows his stuff, "What is the best coil for deep gold?"
His reply was a "20" NF mono."
The coil at the time was a fibreglass Nugget Finder unit, and I purchased one as we were getting some good nuggets at reasonable depths.
My first thoughts when fitting it to my GP3000/GP3500?? on swinging over a 1 grammer was ??????????????????
I persevered for a few hours until my prospecting mate called me over to a signal he had under a fallen tree about 100 mm above the ground level.

I could not get a response!!
His 24" x 12" Coiltek mono had a definite signal.
We shifted the tree and then I got a faint signal. His coil had an obvious response.
???????????
We eventually dug the target and retrieved a 1 gram nugget from around 5" more.
Why the hell did his smaller coil get a FAAAARRR better signal???????????
This should have been an easy target I thought.

I questioned my advisor and was asked if I had a composite upper shaft. to which I had to reply "No."
He suggested that it was the cause of my problem, and highly skeptical me purchased an OTTO complete shaft kit, as I needed a spare lower shaft anyhow.
He was correct. The difference was highly noticable. No longer did the 24" x 12" coil beat me on the deeper bits!!

As I understand it, the larger coils sense the aluminium upper shafts and become de-sensitised.
I believe the reason is that the larger coils, because of their mass, do not sit stationary on the shaft, and actually wobble slightly.
This causes them to "see" or "sense" the aluminium upper shaft and tune it out.
The rule of thumb is any mono coil 16" or larger will benefit from a composite upper shaft.

The main reason that I now produce the fibreglass shafts (that Neil Otto originally developed) is that I firmly believe they are a definite aid in the detection of the deeper lurking nuggets. The reason I don't produce them in carbon fibre (the look is nice, the performance is the same) is the price. I could maybe import the blanks from China and probably sell them at the same or similar price, but I believe that I should do my part in helping Australia and not some foreign country. The tubes I buy are proudly "Made in Australia" and shall remain so.

Do I believe in this product?
You tell me!!

Cheers.

QLD Sandy wrote:Do I believe in this product?
You tell me!!

I do too.    

cheers dave

hi qld sandy

Thanks for the reply. I have a further question that has arisen from your post. You say that due to the mass of the larger coils they wobble slightly and thus the coil can " sense " the aluminium upper shaft and tunes it out resulting in a desensitised coil.

My question is if the coil acts this way to the aluminium upper shaft would it not do exactly the same thing with the 5000's metal box that contains the " brains of the out fit " ( and I'm assuming its metal as I have never pulled one apart ) not to mention the circuitry inside the " box "

Look forward to hearing from you soon.

Cheers

aar

Thanks Dave.

Aar,
I believe the thought train is that the control box is far enough away as to not be a problem as far as I know.
Cheers.

Cheers Sandy