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Coil Ear Bracing: My Approach


ColonelDan

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Coil ear bracing has been the subject of numerous posts so I thought I'd add my approach. Yes, I've used several different  designs of stiffeners and sad to say, my coil ears still cracked and I was out of business until I could replace the coil. Fortunately, those coils were still under warranty. My concern was finding a way to prevent this recurring after the warranty expired.

The ultimate solution is, without doubt, for Minelab to field a redesigned coil ear that is a lot tougher than the current design. Failing that, the best approach in my opinion is to epoxy the stiffener to the coil making the stiffener, the coil and the ears one solid unit. Midalake has done this and as I see it, ensures a solid repair. My concern with this approach would be two fold. One, would that void whatever warranty remains and two, if the coil is sent to Minelab for replacement, there goes the stiffener.

I wanted a method by which I could attach the stiffener to the coil, be able to remove it if necessary and still use the coil cover.

mn90403 has done this as shown on another post within this forum by using zip ties. A workable approach but his method shows the zip ties over the coil cover so you couldn't remove the cover to clean the coil without cutting the ties. Having said that, his system will work as he intended.

I thought I'd share my approach which I've found to be simple yet effective in accomplishing my goals. The key is making the ear stiffener one with the coil so even if the ears snap, the stiffener holds the coil and shaft in place. I decided to use zip ties but in a somewhat different way than mn90403. I wanted the stiffener to be solidly attached and still be able to remove and replace the skid plate.

I threaded the zip tie through and around the stiffener and bare coil without the skid plate attached. I then installed the skid plate over the coil as before covering the zip ties. The skid plate remains in place, the stiffener is solidly attached to the coil and there is no modification to the coil which risks voiding the warranty and if I have to return the coil, I can save the stiffener. Bottom line; with this approach, even if the ears break, I'm still in business.

It works for me....

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ColonelDan:

I like what you have done.  More pictures please.

My purchased system has you attach the yolk after the coil ears have been removed.  I don't use a skid plate on my beach detectors because they only trap sand.  I'm not one to scrape a coil except when pinpointing in a hole.  If I wear out a coil that way then I'll just buy a new one.

The weakness of the ear system on the Minelab coils is that the material is made too thin in part and it can't take the torque applied to the screw which bends both of the coil ears.

This weakness was avoided on another coil and shaft design that I bought on the AQ.  It avoided the breaking issue by having two screws.  There was one for each coil ear!  When you tighten that coil you are making it tight against a 'non-giving' ear and not by trying to bend the ears together with one screw.

Minelab or an aftermarket maker would have to make a lower shaft with two screws that could be tightened on their own but with the closeness of the two coil ears on Minelab coils it might not be possible.  The solution then would be to make an adapter that fits snugly over or in the existing coil ears that does not move or bend the ears.  Once that is attached then a different tightening system provides for adjustment while in use.  There is a need at times to have the coil more loose than at other times but that should not break the coil ears.

I wonder how many of these ears have really broken and how many tens of thousand this has cost Minelab over the years.  It seems their engineers would have worked out a way to save that money on the bottom line of the company.

Mitchel

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ColonelDan,

Where the He*l you been???, long time no see!!!

  I had done mine almost exactly the same, so I can remove the coil cover to clean out the beach sand, and dirt!!

   The only difference is that I cut little slots in the coil cover for the zip ties to not interfere with the coil cover going on! I guess that was just a perceived problem on my part, as you seem to have made it work just fine, without that modification on yours!!

Good show! And don't be a stranger!!👍👍

20210912_203950.jpgJust had it off for a rinse, from today's beach run!! 

  And wanted to add an experience with ML that is applicable!

   I think I showed my last broken coil tab, (one side) somewhere here on the forum! And my subsequent repair with JB Weld, and some fiber washers! It broke just before a trip out of state, so I had no choice but to repair for the trip! When I returned, I explained the situation to ML, and they had me send it back for replacement at no cost, except for initial shipping; under warranty! I was very happy with their response and service, as I've had three under warranty coil replacements, and two Pod replacements from them!!👌 (Thanks ML!)

    I would love to see them solve the few apparent flaws in the Nox, but in the meantime, they are standing by their warranty very well, for me so far!!👍👍

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Here’s a pic of mine zip-tied over the coil skid plate.  Zip ties are pretty cheap so when I want to clean the coil I’ll just cut the zip ties and use two new ones when I put the skid plate back on.  If you use pliers those zip ties can be pulled tight enough to make the coil stiffener feel like it’s one with the coil.  I couldn’t wiggle it once zip tied.  BTW, my coil stiffener was made specifically for my Anderson shaft.  

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FC0EB737-D4E8-4C24-8CC7-2795E8290A95.jpeg

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Each of these methods are admirable and most of all, effective.  
 

When government supplied equipment didn’t measure up ( in this case Minelab supplied equipment) and soldiers took it upon themselves to make improvements, we referred to such fixes as coming from good old “GI Ingenuity” 😃

There’s always more than one route to the objective and you guys have clearly demonstrated that long held truth by applying good old GI Ingenuity.👍

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I have just put my 15" coil on for a night run at a low tide.  When I put it on I thought to myself again that Minelab could have saved itself a lot of money.  What could they do?

They could just make the ears 3/4" longer and put the hole farther from the coil.  My coil ears broke right at the coil because of the pressure applied.  They did not break at the top near the screw hole.  A little more length and flex would allow their design to work.

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41 minutes ago, NCtoad said:

I wonder why no manufacturer never reversed the connection and put the ears on the shaft end and the inner solid part on the coil.  If the ears then broke all you need is a new lower shaft.  

That question has been asked more than once and we're still awaiting an answer from the manufacturers.

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9 hours ago, mn90403 said:

I have just put my 15" coil on for a night run at a low tide.  When I put it on I thought to myself again that Minelab could have saved itself a lot of money.  What could they do?

They could just make the ears 3/4" longer and put the hole farther from the coil.  My coil ears broke right at the coil because of the pressure applied.  They did not break at the top near the screw hole.  A little more length and flex would allow their design to work.

I would not be too hard on your self! The coil ears fail EVERYWHERE because of MFG. DEFECT!  Too much pressure will also crack through the bolt holes as well. 

I know there is only one fix. As guys still break coil ears with stiffeners regardless if their attached with hokey zip ties or not. BELOW, it the only pure fix. 1. Take any coil support that is not made of infill and epoxy it to the coil and coil ears making it as one. 2. Make a custom set of side plates and epoxy them to each side for further support. 

I have 7 months of full use time on my 11" coils already without issue. 7 days a week 3-4 hour hunts, that's about 760 hours of use.  In the worst environment possible , the pounding surf of the Pacific ocean.  

I have recently completed my 15 Minelab coil. Each coil ear is now 1/2" thick.

1704652021_15coil.thumb.JPG.5cd2960a9eb6a6f6d247d5cbb11c7435.JPG

15 coil2.JPG

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Here is the Fisher AQ coil 'system' which I think would be excellent but would probably add a few bucks to a Minelab.

 

herschbach-fisher-impulse-aq-limited.jpg

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