Making A Drag Coil From Scratch

[Northeast]

15 hours ago, Chet said:

I didn’t notice which model you have.

Hi Chet, it is the AI.

I had it over near Bendigo earlier in the week and right from the start it was playing up.  Diagnosed it as a bad coil plug, pulled it apart and sure enough 1 of the solders had let go and another was hanging by 2 threads.   All fixed now and working well in the shed in DD mode.  Noisy as hell with EMI in mono and cancel.  Might give it a little run tomorrow in the bush to see if it is better than last time.

You might be right re: the shape of the lead.  It must be something about that piece as the GPX6 should really have got it.  

10 hours ago, Drellim said:

you are going for the big  one

Thanks but my goal is more about covering a lot of ground when patch hunting in WA, rather than outright depth 👍

10 hours ago, Drellim said:

How you pay attention  to all the sounds and manage that coil  that’s a lot going on

I’ve removed the GP3500 box and the camera battery it uses and put it in a small movie camera bag with a shoulder strap.  It is all contained in there and is light and I run a LL BT sender/receiver set up with some sport headphones to block out a bit of the ‘dragging’ noise.  It all works well (when leads aren’t broken!!) but I am yet to put in a proper 5 hour shift and see if I’m up to pulling it.  All up the coil and lino would only weigh about 7 kg and glides easily over the ground so I don’t anticipate any issues.  After a decent outing and if it all works fine I will move to polycarbonate instead of lino and that will be lighter again 👍

[phrunt]

Won't polycarbonate be really noisy compared to the lino? What about some flat thin rubber matting? 

Drain Mats - NZ Rubber and Foam

 

[jasong]

Good rubber sheet is what I'd try too, unless more rigidity is desired. Rubber sheet is what we used for abrasion resistance in the oilfield on gravels. Industrial hose places sell rubber sheet here in various thicknesses in most towns, dunno if they do over there or not. 

[Northeast]

Yes, conveyor belt was my original plan but I have leaned towards polycarbonate as it is lighter, I think it will be more hard wearing and it will glide much better over rocks whereas as something rubber might bite in a bit.  As I am dragging it myself I need it to have the least resistance and weight possible. 

It is noisy but I can hear the signals fine with my ear buds in.  I suppose it is worth remembering that drag coils are normally used behind a 4x4 motorbike or side-by-side that also provides extra noise and they can still hear the signals 👍

[Aureous]

9 hours ago, Northeast said:

Yes, conveyor belt was my original plan but I have leaned towards polycarbonate

Polycarb is still a plastic and may elicit a static charge from friction with soil and rocks, especially quartz. But it might not in your case, trial and error I suppose. 🤔

[Northeast]

1 hour ago, Aureous said:

Polycarb is still a plastic and may elicit a static charge from friction with soil and rocks,

Oh...had no idea re: that being a possible issue  😳

Thanks for the heads-up and yes, will just trial it and see.  

If it is an issue will it present as EMI?  

[geof_junk]

I think adding 2 narrow rails to the polycarbonate might allow easier for dragging your skid pan with only a slight lose of height.

[Aureous]

2 hours ago, Northeast said:

Oh...had no idea re: that being a possible issue  😳

Thanks for the heads-up and yes, will just trial it and see.  

If it is an issue will it present as EMI?  

Yes, loud, sharp erratic pings as it discharges. Ya dont wanna touch any statically charged plastic either, electric shock will occur. Maybe a trailing discharge wire will help...

[Chet]

I found some good user information at the website below. The Double D mode is the proper mode.

https://www.fortbedfordmetaldetectors.com/coiltek-drag-coil-goldhunting-anti-interference

 

[Johnno481]

This is the best stuff to use for the skid plate; "high or ultra high molecular weight polyethylene" , google it. You would still be better off though, using a 30 x 7 Patch Finder coil which "will give you a 10' swing coverage and you can walk at full pace.