Carbon fibre upper shaft on a 5000

View previous topic View next topic Go down

Carbon fibre upper shaft on a 5000

Post  happydiggings on Fri Nov 04, 2011 10:42 pm


I have a GPX5000 would a carbin fibre upper shaft make much differance to the overall performance of the machine, more so with the larger coils?

Thanks Bob

happydiggings
New Poster
New Poster

Number of posts : 4
Age : 59
Registration date : 2011-02-22

Back to top Go down

Re: Carbon fibre upper shaft on a 5000

Post  Inhere on Fri Nov 04, 2011 11:17 pm

Worth having for 16" mono's and over! Wink
avatar
Inhere
Contributor Plus
Contributor Plus

Number of posts : 933
Registration date : 2009-02-06

Back to top Go down

Re: Carbon fibre upper shaft on a 5000

Post  nero_design on Fri Nov 04, 2011 11:28 pm

A larger coil (17"+) often benefits from a longer shaft to help keep it as far away from the metal on the user as possible. Larger coils seem more stable when using longer shafts (in my opinion).

Carbon fiber is very strong but it is also electrically conductive. On a functional detector, it makes a spectacularly powerful lightning rod. I read about plenty of people selling Carbon Fiber shafts but few seem to take into account the conductive properties of this material. Just as you can use a lead pencil (with graphite/carbon cores) to short two electrical terminals, using one on a detector may or may not be a problem for the user.

The Otto Shafts were said to be made from fiberglass (incorrect) and then carbon fiber at one point (also incorrect) though I have been told that they are made of machine-wound Kevlar. If you look at the unglazed sections of the shafts, you can make out the Kevlar. It may be that the machine-wound Kevlar is over a thin fiberglass shell but the fibers are bonded with a special annealing epoxy that makes them very hard to break. There are also no-name fiberglass shafts available in 700mm lengths that are more price competitive than the OTTO shafts but the material used on those is unknown to me.


Extreme Closeup of some of my 800mm Otto Shafts showing the machine-wound Kevlar strands.


Extreme Closeup of one of my Otto Shafts showing the strands with the smooth glazing over the top.


800mm Otto lower shaft with 18" NFA coil on one of our GPX5000s... with ACU Digital Camo tape over the shaft.
avatar
nero_design
Contributor Plus
Contributor Plus

Number of posts : 1907
Registration date : 2008-11-18

Back to top Go down

Re: Carbon fibre upper shaft on a 5000

Post  detectoraid on Sat Nov 05, 2011 7:03 am

While its true that carbon/graphite is somewhat conductive, restive is a more accurate description. Isn't carbon used to make resistor cores? In the application of carbon fiber shafts the fibers are insulated by the resins. So our bodies would make a far better lighting conductors then a carbon fiber shaft.
Regards,
Chris Porter
detectoraid.com


Last edited by detectoraid on Sat Nov 05, 2011 7:07 am; edited 1 time in total (Reason for editing : typo)
avatar
detectoraid
Good Contributor
Good Contributor

Number of posts : 109
Registration date : 2008-12-13

Back to top Go down

Re: Carbon fibre upper shaft on a 5000

Post  nero_design on Sat Nov 05, 2011 9:08 am


It's exactly the same as using a carbon fishing rod. Strong in terms of tough... but still a powerful lightening rod. The carbon mesh percentage will be high enough to cause occasional conductivity probelms with the PI detectors... which is exactly why it's not supplied from the factory this way. It's also why people using carbon fiber rods have occasionally complained in the past on US websites. If you really want to cut down your noise with a large coil, you should cut a length of inflexible hardwood dowel and drill it to accept the upper shaft bolts near the arm rest and the lower bolt hole for the coil. That method, though not as easy to transport, it the most superior that I know of.
avatar
nero_design
Contributor Plus
Contributor Plus

Number of posts : 1907
Registration date : 2008-11-18

Back to top Go down

Re: Carbon fibre upper shaft on a 5000

Post  Inhere on Sat Nov 05, 2011 10:00 am

Chris is quite correct, try and detect the shaft with a small coil.

I have never had a problem with carbon fibre fishing rods either.
Well maybe once, just make sure they are inside the car before you shut the door. Embarassed Very Happy
avatar
Inhere
Contributor Plus
Contributor Plus

Number of posts : 933
Registration date : 2009-02-06

Back to top Go down

Re: Carbon fibre upper shaft on a 5000

Post  Flakmagnet on Sat Nov 05, 2011 12:04 pm

Inhere

sorry about the fishing pole lol!
avatar
Flakmagnet
Contributor Plus
Contributor Plus

Number of posts : 395
Registration date : 2008-12-31

Back to top Go down

Re: Carbon fibre upper shaft on a 5000

Post  detectoraid on Sat Nov 05, 2011 12:23 pm

I will agree on the point of "inflexible" my testing indicates this is where carbon fiber shafts excel, more so at longer that stock lengths. IMHO shaft flex is one of the reasons ML supplies a ridged material as their stock upper (the main reason is cost).

I will theorise that:
Carbon fiber shafts preform the same way that carbon impregnated paper shielding used in coils does. Based on the fact that carbon is a better resistor than conductor.

I happen to have a sample of carbon fiber matting from a mast maker, I tried to pass a current through it, from low voltage to high amperage (an arc welder) I suggest you try it and you'll see why it would make a lousy lighting rod.

Regards
Chris Porter
detectoraid.com
avatar
detectoraid
Good Contributor
Good Contributor

Number of posts : 109
Registration date : 2008-12-13

Back to top Go down

Re: Carbon fibre upper shaft on a 5000

Post  Sponsored content


Sponsored content


Back to top Go down

View previous topic View next topic Back to top

- Similar topics

 
Permissions in this forum:
You cannot reply to topics in this forum