Broken Minelab CTX 3030 Coil Ear

[phrunt]

Well, my coil ear strengtheners arrived from the UK about a week ago but I didn't bother to deal with them until today as it is raining 🙂

So far I've completed one of them, my 17" coil which had a small hairline crack in the left coil ear, it had not broken through but not all that far off it, not very good for a coil under a year old.  I didn't want to bother with warranty as I intended to strengthen the ear anyway even if they did give me a replacement coil.  I have absolutely no faith in those skinny ears on a 17" coil after mine developed a crack without doing anything even stressful on it like water hunting, this was just normal everyday field hunting.

Yes, there is all this rubbish about not over-tightening the coil bolt, and I'm sure in many cases that may save your ears but I didn't over tighten mine, and even if I did that should not break an ear, on  any other detector with a better quality coil other than my Nox/Vanquish with the same substandard ears I've never had to care if I over tighten my bolts and nobody should have to care if they do or Minelab should put a big warning on the packaging saying it has weak ears do not over-tighten the bolts.  This is a Minelab problem and it's ridiculous the problem exists and has been left like it is for so many years.  How old is the CTX now? With my research people have been breaking ears on it since not long after it came out, and my CTX being relatively new still has the problem all these years later.  Pretty poor Minelab.  Get your act together, yes performance is everything but a bit of quality doesn't hurt either.

So the ear strengtheners from UK were decent, I never did find a 3D print design I could use so buying was my only option.  They seem strong and before even putting one on I tried to break it to see it was strong enough, it handled being over tightened with a bolt in it as tight as I could reasonably get it no problems so that was a good sign.

I didn't want to just sit the coil ear strengthener on there as I see that as completely pointless, they break from bending inwards when you tighten the bolts with Minelabs weak plastic formulation and thin ears so without Epoxy the strengthener is absolutely useless.  I used Norski Epoxy that comes in a white colour but has pigment you can buy to colour it whatever colour you want so I used black of course.   This epoxy is awesome and very tough, once set you can sand or drill it and so on, it goes rock solid. 

This is the 17" coil completed with strengthener fitted, with the black epoxy it doesn't look terrible like the ones I've seen glued with white epoxy, I'm to fussy to do something like that.

I put a lot of epoxy on so the entire strengthener is glued on, no gaps anywhere for sand or dirt to get under the thing.  The great thing about this epoxy is 10 or so minutes after applying it when it starts to firm up a bit you can wipe it away with water, it takes a bit of effort but it wipes off leaving only what you want so I was able to do a pretty neat job.

Every spot the ear strengthener joins to the coil is epoxy filled so I've got no concerns about dirt getting under it, it will also make the strengthener significantly stronger.

I am yet to do my 11" coil, it hasn't got any issues yet but I'll do it anyway as I can't be bothered dealing with broken ears in the future.

Here is the 11" strengthener just sitting on the coil, These ones from the UK are decent as the ear is very thick, so thick to use the standard bolts he's had to indent a bolt hole into them, quite a good design.

You'll see the indent for the nut.  It also has a cable tie holes but I won't be using them, I'm going to epoxy it on like the 17" so that hole will end up filled with black epoxy.

They're quite a nice fit but enough room everywhere for a reasonable amount of epoxy to hold it all together solidly.

I also made my own little shims to put on so it prevents the ears from bending in when over tightened, I've permanently epoxied one of these onto the 17" coil on one side of the ears on the inside with the same black epoxy, I can tighten it up as much as I want now, no bending of the ears and a solid tough ear anyway.  It's like they made the shaft a slight amount too small or the coil ears spaced a tiny amount too big.  My rubbers aren't old but I bought some new ones to see the difference and there was no difference, the little shim fixes that problem up nicely.

Another stupid design flaw with the CTX is how the coil cable goes up into the shaft, the shaft constantly rubbing on the cable is causing damage to the cable, at the moment it'was just a little dent in the cable but I can imagine with a lot of use that could get worse, and I've done my reading and people have had coils fail from damage down near the coil strain relief where the shaft rubs on the cable.  So I took a preventative measure there too and shrunk down some dual wall adhesive lined heat shink over the part of the cable where it rubs,  Now any damage will be to the heat shrink and if it gets bad I'll warm it up and take it off again and replace it.

You can see in this photo where the glue is coming out of the heat shrink that holds it on secure, no way is the cable getting damaged with that in place. 

This is all stuff I shouldn't have to do, but seeing the quality of the coils is substandard it becomes necessary, maybe let Nel make coils for your gear Minelab, they know how to make good quality coils.

I'm not going to bother doing my little 6" CTX coil unless I see a problem, the weak flimsy little ears should handle the load of that little coil OK I would hope.

[mn90403]

Simon,

I agree that Minelab has not listened to those of us who have had failures over the years.  They would have abandoned this coil ear design long ago if they had listened.  I think it is these issues that have piled up and added up to affect the Minelab stock price you were talking about in another thread.  There is just not enough profit to replace coils, shafts, leaky control units and provide the shipping also under warranty.

My CTX 17" and many others like me failed a couple of years after I bought mine new when they came out.  I took pictures and sent them to Minelab showing how my coil ears broke and suggested a fix without any response.  I think the coil ear material is just too brittle to handle the torque pressure near the coil from the big screws.  Over the months and months of it just being tight in and out of use the base just has to give.  It cracks just as you describe.  Shims would help but are a pain to use if you change a coil.  You have to have a neutral position for the ears or even a fraction of inward pressure will crack it.  Minelab should have another system but I bet this is the least expensive way.

Your fixes look good.

Now where are you going to use it?  haha

[phrunt]

Yes, it must be costing them a fortune in warranty repairs and often replacements for all the faulty detectors and coils and the shipping involved with replacements.  How much confidence do people have with the GPX 6000 especially Facebook users after reading the abnormally high number of people with faulty ones but even on here the ratio of people that own one vs people that have had failures is absolutely shocking.  You don't pay that sort of money and have such a high failure rate, if they were cars they would have been recalled by now.   I'm not going to get one until they sort themselves out, maybe in 6 months or a years time a newer batch will be more reliable, I don't really need it anyway as I'm very happy with my current setup.

The Nox and all the leaking on the regular beach hunters and broken coil ears and early on the wobbly shafts.  It's really not a good look and I can imagine as soon as another brand catches up in performance many will jump ship to a better quality product.  They've got the performance going strong, their build quality is subpar.   Perhaps now they're starting to get some competition things might improve on future models, I certainly hope so.   The leaks I'm not so sure about with the Nox, it could be the massive number of people using it in the water and perhaps exceeding the specifications on depth causing that so that's an iffy one but there is absolutely no excuse for the weak coil ears other than a poor quality product, it doesn't even happen on cheap generic entry level detectors.

I'm quite new to all of this but reading back at all the faults people have had with the CTX right from new with lines on the screens, ears breaking, drowning the detector, coil cable damage... I could go on and on.   It's not like it's a cheap and nasty detector.

My little shims I epoxy on so they're not difficult to use, I first tried just putting it in place and that was a pain, epoxied on they're no different than not having one.  I cut them out of a plastic container that nails come in, it's tough plastic as I wasn't able to break the container, even jumping on it I just crushed it down but it didn't break so I cut a few little shims out of it 🙂

I've been using the 17" coil at my Cointopia and finding many silver coins I missed with the Nox.

[phrunt]

This is how you make a coil and it's ears

Do this with your Equinox or CTX and it will explode into little microscopic fragments, and so will every other Nox/CTX coil within a 10 mile radius from the shock-wave of the beating the coil is taking.

[mn90403]

Chopping down a little tree!  haha

Amazing.

[GB_Amateur]

I wonder if differential expansion has an effect.  Basically, most materials shrink or expand with changes in temperature (typcially shrink on cooling and vice versa on heating).  Two neighboring materials in contact may have different coefficients of expansion and thus change sizes differently when cooled (or heated).  This *could* be exacerbated in lake or ocean water if that water is consdirerably colder than the air temperature.

The coil ears are plastic; they mate with some kind of synthetic rubber gasket; those gaskets are in contact with the shaft (usually plastic); all are held together with a bolt and nut (again, usually plastic).  If the coefficients of expansion are matched or at least close then this won't be an issue.  Are they?

[phrunt]

I'm not sure it's that technical, and if so every other manufacturer has worked it out except Minelab.  They put too thin and too weak ears on, it's really that simple.  Even if someone over tightens a bolt that should not break their ears off, if it does it's a bad design.  I was once one of those people that said my ears never break, it'll never happen to me...... then it did.

[midalake]

I just have to repeat this [again] 

Coil Stiffeners are USELESS unless epoxied to all surfaces of the original coil mount. 

[phrunt]

5 minutes ago, midalake said:

I just have to repeat this [again] 

Coil Stiffeners are USELESS unless epoxied to all surfaces of the original coil mount. 

Yes mine is epoxied everywhere.

[bklein]

Did you use PVC glue or instead ABS glue?  I would think the ABS glue would be better but it is kind of rubbery/flexible so just to glue major surfaces.