Making A Drag Coil From Scratch

[Northeast]

8 hours ago, GotAU? said:

Jim Straight’s Bismarck coil for a Coiltek Mothership 40x20 coil

Thanks GotAU.  Although that set-up is weighted better I'm trying to find an alternative to the side-to-side swinging motion.  Walking/pulling in a straight line seems like it would be better on the body long term  ?

7 hours ago, Ridge Runner said:

This coil is a blanket that you can drag behind just about anything you want.

Actually seems like a decent option RR, thanks.  Made in Idaho - I wonder if @Gerry in Idaho has seen them out and about?  Looks like you have to use their P.I. module though.  And shipping to Australia - I don't even want to know ?

5 hours ago, jasong said:

Are you aiming to cover ground or aiming for depth on patches?

Definitely ground coverage in the first instance Jasong.  Depth is just an added advantage.  

 

However, I think the option below will give me both.  It could be laid out in a wide oval shape to get ground coverage.  Then, if a patch is found or I wanted to go over the B-I-L's original patch (found 1/2 a kilo and counting) then it could be shaped into a 50" round coil.   

https://detectormods.com/shop/77/flexible-drag-coil

 

 

[GotAU?]

1 hour ago, Northeast said:

Thanks GotAU.  Although that set-up is weighted better I'm trying to find an alternative to the side-to-side swinging motion.  Walking/pulling in a straight line seems like it would be better on the body long term  ?

 

 

How about pulling the 40x20 CT Mothership coil sideways on a little PVC pipe cart or sled?

[blackjack]

I tend to agree with GotAU? I think wheels or at the very least I guess a sled. I'm just asking the question 'why did someone invent the wheel', my answer would be because they were using a sled. Seems like people have come up with some good options for you N/E keep us informed, on your progress.

[Northeast]

5 hours ago, GotAU? said:

pulling the 40x20 CT Mothership coil

Yes, that is an option.  I am looking for something a little wider though (60" - 72") to really cover some ground.  

[Northeast]

4 hours ago, blackjack said:

I think wheels or at the very least I guess a sled.

Wheels and PVC tubing to make a sled are certainly an option too.  I am trying to keep it really simple for a couple of reasons though.  The first is so that there is less to go wrong out in the field.  Second is that the more moving parts means it is more complex to make and everything needs to be metal free.  Not impossible but harder.   The third is that I will certainly use it here in Victoria on farms, etc, but it is really being purchased to take to the wide opens spaces of Western Australia.  Something like Woody's loop could be easily shipped to my brother-in-law in Perth before I fly across there and he can simply have some conveyor belt and ropes organised. 

The ideas around the sled make up are appreciated but it is more the make up of the coil that is the concept that is outside my boundaries.  I have had a generous offer of assistance from a Prospecting Australia member to provide some info around that and will definitely keep you updated re: if I proceed with making the coil myself  ?

[Valens Legacy]

Grandfather has made some coils for relic hunting using the same method as a prefab vehicle detection coil.

They are 72 in. long by 9  in. wide and work with a 2k detector. The coil is enclosed in 1/2 in. plastic conduit sealed at the corner where the wires go into the pipe. They are twisted together and then ran to the detector which can be up to 50 feet away from the coil. The pipe has 4 lawn mower wheels attached to it on each corner with plastic bolts, so that it would roll across the ground with ease.

I hope this helps with your design, and I wish I was at home to take a picture of them for you but I won't be back there for several months.

[blackjack]

Yeah, I understand, it would be the coil arrangement that would trouble me as well. The rest of it can evolve. after all you'll be the one dragging it.

[Reg Wilson]

The coil attributed to Jim Straight was built by Jim Stewart in Victoria Australia.

[Reg Wilson]

If you are going to go sledding then you need to spend money. No cheapskate option will cut it. 

You need a diesel tow vehicle with an alternator cut out switch to keep the coil close behind. ( a 4stroke will send your detector nuts with interference) A diesel causes no EMI. 

A rigid coil frame attached to heavy duty conveyer belt for rugged or abrasive terrain. (Desert country will shred PVC in no time.)

The right detector for the job. (I have found the GPX 4000 the best option)

These are just the basics but set up right you will easily pick up targets as small as .22 slugs at several inches. Tested on a real big slug (over 90ozs) at over a meter the detector just roared.