Equinox Coil Ears

[midalake]

Epoxy a coil support on that baby!!!!  Make sure it works first😉

[GB_Amateur]

Add another datapoint to the breakage bin.

On Thursday, with nice weather (~50 F = 10 C) and sunny I was loading my gear into the SUV for an afternoon detect in my current site (muni park previously an industrial yard).  When travelling near home with my detector I just leave the shaft extended to it's optimal (for me) length, coil attached -- ready to hit the ground running.  It fits across the floor of my backseat just fine.  I've been doing things this way since I got my ML Equionox 800 in late March 2018.  (Relevant Note:  3 year warranty has expired).  As I was putting the detector in the back seat (coil first...) I bumped the coil on something, probably either the near car door (standing open) or more likely the back of the front seat.  I heard a 'crack' sound, not too loud, and at first was going to ignore it.  And then I remember this and many other threads on the same subject....

Taking the detector out and looking at the coil attachment area it didn't take but a fraction of a second to see the source of the noise.  The top of the tab had broken completely through at the location where the through bolt passes.  Fortunately I had my 6" coil in the vehicle (always try to bring it along) and better yet, the 12"x15" inside so I put on the latter and my afternoon hunt survived.  (I'll make a separate post on the results of that, which included a detecting first for me.  Stay tuned for that.)  I did check the tightness of the wing nut and it was not very tight; definitely not what I would call over-tightened.  Further, thanks to phrunt's suggestion I've been putting spray silicone lubricant on all my rubber coil gaskets (not just on Eqx but on other detectors as well) to minimize the friction when the coil is rotated.  I will state (obviously without proof) that I didn't use a lot of force loading the detector and that I'm confident I've torqued the coil similarly on many occasions in the past without incident.

Now let's review the history of this coil while in my possession (since it was new in box).  Only counting local detects and only counting days when the only detector+coil I used was the Eqx+11" stock, reviewing my detecting logs I see that I've hunted with this coil for 820 hours.  I probably have another 40-80 hours with the coil if I were to include remote hunts (e.g. this past June in Utah and this past August in Massachusetts) plus those days when I hunted with multiple detectors or the Eqx with multiple coils.

Probably more relevant is that I've modified my shaft by replacing the two lower sections with the ML X-Terra 705 lower sections so in fact the Eqx coil(s) is attached to an X-Terra lower shaft.  Does this enter into the investigation?  Yes.  Let's delve deeper.

Of those 800-900 hours that the 11" coil has been in use, between 450 and 500 of them (the most recent) were with this modified shaft.  Could there be a tolerance (would 'intolerance' be a better word) issue?  Here are some measurements I just made this evening.  (Note:  measuring soft items is a bit tricky but more complicated than that, measuring a stack of items in which there are 'mushy' contacts between them, such as rubber gaskets embedded in plastic insets -- exactly what we have here -- leads to some measurement uncertainties.  Thus I give a range of thickness measurements for each combination.)

1) My Equinox stock shaft with used = ~400 hours wear gaskets:  0.890-->0.899 inches.

2) My current setup (X-Terra lowest shaft w/used = ~500 hours wear gaskets:  0.882-->0.884 inches.

3) Brand new (unused) Anderson lower shaft for X-Terra with one shim (included in purchase and determined by me to be the right amount of adjustment):  0.894-->0.897 inches.

4) Brand new (unused) ML stock X-Terra lower shaft purchased from Gerry earlier this year:  0.896 --> 0.902 inches.

5) Opening on my slightly used ML Equinox 12"x15" coil:  0.889-->0.894 inches.

BTW, for those who prefer metric measurements, 0.010 inches is about 0.25 mm.  Looking over these numbers, the X-Terra and Equinox shafts are likely pretty close when everything is new.  The thing that jumps out is that my used X-Terra lower shaft (gaskets 'used' exclusively with the Equinox coils) are about 0.010 inches thinner than everything else.  I don't know if we can call that a smoking gun, but it appears those gaskets have worn over time.  Is that current combination enough to lead to stress that caused this breakage?  I guess Minelab engineers should be able to answer that -- they've seen enough returned coils with broken ears to figure out what's going on....

To add a bit more evidence (admittedly anecdotal), I do recall measuring things when I changed from Eqx stock shaft to X-Terra shaft almost 2 years ago and the difference then was not 0.010 inches or I would have added shims to make up the difference.  I don't know how the gasket compounds compares between Equinox and X-Terra but it sure appears that the X-Terra gaskets wear measurably with time.  (I have a spare set of those plus the ones on the shaft I bought from Gerry.  Time for a change now that the horse has escaped through the open gate....)

So, what next?  This next picture (with broken coil attach tab piece and bakelite washer I've had salted away since I was in high school > 50 years ago) gives a big hint.

I'll report the results of this garage fix in a couple days after I see if it works.

Update:  first a picture of my gluing jig:

5/16" drill bit (8 mm would have been slightly better but I don't have one of those) and three stop collars.  Two of the stop collars 'pin' the (broken) ear and reinforcing bakelite washer in place.  Note:  epoxy likes to bond metal so I waxed (with automobile paste Carnawba wax) the drill bit and the stop collars.  One of the stop collars and the drill bit still stuck but my handy ViseGrip and careful rotation of those broke them loose without damaging the new joint -- all that after an overnight cure.

Here is the finished fix:

I lightely filed (with a very fine file) the inner tab surface that mates with the shaft's washer just to clean up any epoxy overslop.  Next step is to silicone spray lube new washers and give it a go in the field.  Unless my fix fails I see no need to report back (other than posting pics of all the goodies).  Fingers crossed.  🤞

[steveg]

GB_Amateur...

Yep, from my perspective, I would suspect that washers worn down .01 inches (0.254mm) would be a stressor on the Equinox ears...that's over 1/2mm less "width" of your lower rod to fit between the coil ears.  Given that we know the Equinox's ears are, shall we say, less than "stout," and prone to breakage, that would be enough of a difference (1/2mm too small on the lower rod's "width") to be at least suspect...

The .890 to .899 inch measurement range you stated, with respect to your stock lower width, is exactly correct.  22.70mm is what the stock shaft usually measures for me, and that is what I aim for with my shafts as well, or perhaps a hair larger  (22.70mm is .894" -- right in the middle of the range you stated). 

As you are noting, given the Equinox ears' propensity for breaking, a bit more attention is required as you note.  When the washers wear down a bit (usually an issue for beach hunters), a washer swap is a good idea...OR...an alternative idea is the use of spacers "behind" the washers (as you noted).  Along these lines, I now am selling 0.2mm thick "spacers" that are designed fit behind the washers (installed inside of the "washer cavity" in the lower rod head prior to washer installation), for just that reason.  Using such a spacer behind your washer, to "replace" the lost washer thickness that can occur over time (by "pushing" the washer "out" a bit, thus recovering some of that lost width) can be helpful in this regard (that, or a washer replacement).  

SORRY to hear about your coil ear breakage.  Frustrating...

Steve
 

 

spacer installed behind the washer...

 

 

[mh9162013]

 

Add another datapoint to the breakage bin.

On Thursday, with nice weather (~50 F = 10 C) and sunny I was loading my gear into the SUV for an afternoon detect in my current site (muni park previously an industrial yard).  When travelling near home with my detector I just leave the shaft extended to it's optimal (for me) length, coil attached -- ready to hit the ground running.  It fits across the floor of my backseat just fine.  I've been doing things this way since I got my ML Equionox 800 in late March 2018.  (Relevant Note:  3 year warranty has expired).  As I was putting the detector in the back seat (coil first...) I bumped the coil on something, probably either the near car door (standing open) or more likely the back of the front seat.  I heard a 'crack' sound, not too loud, and at first was going to ignore it.  And then I remember this and many other threads on the same subject....

Taking the detector out and looking at the coil attachment area it didn't take but a fraction of a second to see the source of the noise.  The top of the tab had broken completely through at the location where the through bolt passes.  Fortunately I had my 6" coil in the vehicle (always try to bring it along) and better yet, the 12"x15" inside so I put on the latter and my afternoon hunt survived.  (I'll make a separate post on the results of that, which included a detecting first for me.  Stay tuned for that.)  I did check the tightness of the wing nut and it was not very tight; definitely not what I would call over-tightened.  Further, thanks to phrunt's suggestion I've been putting spray silicone lubricant on all my rubber coil gaskets (not just on Eqx but on other detectors as well) to minimize the friction when the coil is rotated.  I will state (obviously without proof) that I didn't use a lot of force loading the detector and that I'm confident I've torqued the coil similarly on many occasions in the past without incident.

Now let's review the history of this coil while in my possession (since it was new in box).  Only counting local detects and only counting days when the only detector+coil I used was the Eqx+11" stock, reviewing my detecting logs I see that I've hunted with this coil for 820 hours.  I probably have another 40-80 hours with the coil if I were to include remote hunts (e.g. this past June in Utah and this past August in Massachusetts) plus those days when I hunted with multiple detectors or the Eqx with multiple coils.

Probably more relevant is that I've modified my shaft by replacing the two lower sections with the ML X-Terra 705 lower sections so in fact the Eqx coil(s) is attached to an X-Terra lower shaft.  Does this enter into the investigation?  Yes.  Let's delve deeper.

Of those 800-900 hours that the 11" coil has been in use, between 450 and 500 of them (the most recent) were with this modified shaft.  Could there be a tolerance (would 'intolerance' be a better word) issue?  Here are some measurements I just made this evening.  (Note:  measuring soft items is a bit tricky but more complicated than that, measuring a stack of items in which there are 'mushy' contacts between them, such as rubber gaskets embedded in plastic insets -- exactly what we have here -- leads to some measurement uncertainties.  Thus I give a range of thickness measurements for each combination.)

1) My Equinox stock shaft with used = ~400 hours wear gaskets:  0.890-->0.899 inches.

2) My current setup (X-Terra lowest shaft w/used = ~500 hours wear gaskets:  0.882-->0.884 inches.

3) Brand new (unused) Anderson lower shaft for X-Terra with one shim (included in purchase and determined by me to be the right amount of adjustment):  0.894-->0.897 inches.

4) Brand new (unused) ML stock X-Terra lower shaft purchased from Gerry earlier this year:  0.896 --> 0.902 inches.

5) Opening on my slightly used ML Equinox 12"x15" coil:  0.889-->0.894 inches.

BTW, for those who prefer metric measurements, 0.010 inches is about 0.25 mm.  Looking over these numbers, the X-Terra and Equinox shafts are likely pretty close when everything is new.  The thing that jumps out is that my used X-Terra lower shaft (gaskets 'used' exclusively with the Equinox coils) are about 0.010 inches thinner than everything else.  I don't know if we can call that a smoking gun, but it appears those gaskets have worn over time.  Is that current combination enough to lead to stress that caused this breakage?  I guess Minelab engineers should be able to answer that -- they've seen enough returned coils with broken ears to figure out what's going on....

To add a bit more evidence (admittedly anecdotal), I do recall measuring things when I changed from Eqx stock shaft to X-Terra shaft almost 2 years ago and the difference then was not 0.010 inches or I would have added shims to make up the difference.  I don't know how the gasket compounds compares between Equinox and X-Terra but it sure appears that the X-Terra gaskets wear measurably with time.  (I have a spare set of those plus the ones on the shaft I bought from Gerry.  Time for a change now that the horse has escaped through the open gate....)

So, what next?  This next picture (with broken coil attach tab piece and bakelite washer I've had salted away since I was in high school > 50 years ago) gives a big hint.

I'll report the results of this garage fix in a couple days after I see if it works.

 

If JB Weld doesn't fix it, it can't be fixed...

Just sayin'

[GB_Amateur]

 

Yep, from my perspective, I would suspect that washers worn down .01 inches (0.254mm) would be a stressor on the Equinox ears...that's over 1/2mm less "width" of your lower rod to fit between the coil ears. 

@steveg  I don't see why you multiplied by 2.  My measurements weren't of the individual washers but rather the 'assembled' size (washer + shaft well + washer).  But 10 thousandths of an inch (1/4 mm) out-of-tolerance being a problem -- I can at least envision that.  Thanks for your confimatory response.

The stock X-Terra washers aren't flat but rather have (large) teeth in the back which fit into cavities in the shaft to prevent them from rotating.  (Why did ML engineers go to that much trouble to prevent rotation of the washers?  I don't know.)  But, yes, the stock Equinox shaft (and also the X-Terra replacement aftermarket Anderson shaft) have the simple flat washer for which a shim is easily accomodated.

I wonder if the 'phrunt solution' of lubricating the washer with silicone spray reduces the amount of frictional wear.  I did lubricate mine quite a while back but I think I'll try doing that every 15-20 hours or so of field use.

[Joe D.]

Well GB,

   You got a lot more hours out of yours, than I did, out of my three coils! And by the way, may I suggest the JB "Quick" weld and fiber washers  over the regular JB weld! I made a little form for my broken tab and used a piece of appropriate sized silicone straw to keep the hole intact! (I did not have the broken piece) Than filled with the quick weld! In this way, I kept the shaft slot the same, and added the fiber washers to the outside of the hole! Worked great, as you don't have to wait all day for the quick weld to set up, like the regular!!

   That was the one that I repaired, just before a trip out of state! When I returned, ML got sent that one, and I got a new one under warranty! 

   Since than, I have used a tab protector, and altered the coil bolt so that it doesn't put as much stress on the outside of the tabs! So far so good!🤞

   This is what I did to the coil bolts! First I filled with silicone, than set a nylon washer just above the surface of the bolt face! No more beach sand filling the gaps, and now the force is more evenly spread across the whole bolt face, instead of that minute edge, which i think is another design flaw, which is adding to the tab failure!!👍👍

 

 

 

[GB_Amateur]

@Joe D. Thanks for the tip.  A couple things:

1) I'm not using the Eqx bolt+nut becauase I use the ML X-Terra lower shaft and that takes a smaller size.

2) There was a YouTube video posted here (can't remember anything but the images and content...) by a regular YouTube poster from Southern USA (some kind of thick accent...) where he experiments with different adhesives and epoxies.  The one I've chosen did best in his testing.  It actually interacted with the pieces being attached -- almost like melting and re-solidifying.  I like that solution but don't know if it will work for the plastics I'm using.  I'll find out....

I've tried multiple epoxies in previous garage mods, including two whose manufacturers claim will bond injection molded plastics.  They all failed....  The one I've chosen for this task hasn't failed me (yet) because this is the first time I'll be trying it.  😏

[strick]

 Sorry to hear that the coil ears broke I still have yet to break one knock on wood JB Weld is some good s#*t . I’m still on the fence about those coil stiffeners I am using one as I sit here in bodega bay and I do not like the torque is placing on the coil ears so I’m going to take it off...

strick

[GB_Amateur]

 

I’m still on the fence about those coil stiffeners I am using one as I sit here in bodega bay and I do not like the torque is placing on the coil ears so I’m going to take it off...

I'm with you, strick.  My go-to mantra (with exceptions, as always) is "if it ain't broke, don't fix it."  Next in line:  "if it is broke, try the minimum fix first."  Having spent most of my career in a position where I and my cohorts were doing things no one else had likely done (nor wanted to for that matter) we tried a lot of 'solutions'.  Sometimes the cure was worse than the disease because of over-design.

[Joe D.]

   I don't know if anything i have done on this coil will be successful; time will tell!! But I can tell you that having done nothing other than changing the ML washers, and watching how tight the coil bolt torque is, has been unsuccessful for me thus far!!

   And GB,

   I have had the same problem with those "supposedly" plastic bonding adhesives! No good bonding!! I even tried some the cures instantly with a UV light applied; too soft, and didn't hold up!! JB Weld, with good surface prep, has been a winner for me!! I actually remember my Dad fixing a manual shifter ball with "JB", in his old 74, Bronco! And not the one you put your hand on to shift but at the other end in the manual transmission!!👍👍