Gluing magnets?

MrBlackCrowMrBlackCrow Posts: 21
edited December 2017 in Vintage Speakers
Hi y’all, someone here recently posted a thread about gluing magnets on their speakers. Though, they stated they were gluing them before playing the speakers- like not for drivers that were about to be shipped somewhere. I’ve heard about magnet shift before. My question is: can magnets shift just under normal playing conditions? Thanks
Music hall MMF-2.2 > musical fidelity V-LPS 90 or NAD C516BEE > California Audio Labs Sigma 2 > Emotiva XSP-1 G2 > Emotiva UPA-1 (x2) > vintage Polk Audio monitor 5A w/ peerless

Comments

  • pitdogg2pitdogg2 Posts: 9,657
    Yes. Once the super glue used to bind the magnets lets go then the magnet flux will shift. You know when you try to push two magnets together how you get that sort of force field then they come together a little to the left or right? Same thing when it lets go except this time there is a voice coil in the middle.
  • Rrusse11Rrusse11 Posts: 116
    I see lots of advice on pre-emptive gluing of the driver magnets, and a variety of recommendations on various products from epoxy (rigid) to construction adhesives (flexible). I'm thinking that hot glue would be one way to go, run a bead of that as
    a seal/reinforcement.
    Thoughts from those with experience?
    Cheers,
    R*2
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  • FestYboyFestYboy Posts: 2,193
    I can say no to this. Hot glue isn't stiff enough, nor will it bond to the magnet or pole plate.
  • Rrusse11Rrusse11 Posts: 116
    Thanks FestYboy! I'm leaning to epoxy then. I've got some putty type that I can knife in, and tool easily "green" for a neat finish.
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  • I used the loctite express power grab and it seems to have worked. It dries rock hard.
    Music hall MMF-2.2 > musical fidelity V-LPS 90 or NAD C516BEE > California Audio Labs Sigma 2 > Emotiva XSP-1 G2 > Emotiva UPA-1 (x2) > vintage Polk Audio monitor 5A w/ peerless
  • Rrusse11Rrusse11 Posts: 116
    I used the loctite express power grab and it seems to have worked. It dries rock hard.

    Ahhh, never used the stuff, thanks for the detail. I'll have a look at Lowes or HomeDepot for it.
    Cheers!

    SDA SRS 2.3s
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  • verbverb Posts: 2,405
    Yep good stuff highly recommended. You can use it to seal your cabinet as well.
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  • Rrusse11Rrusse11 Posts: 116
    So I grabbed a tube of the "Heavy Duty" Loctite and laid a bead into 16 drivers. Tools ez with a wet finger and sets up nice and solid. Possibly a bit of a "belt & braces" approach, but it obviously reinforces the original factory glue bond. Can't hurt,
    and may well help prevent catastrophic failure.
    Cheers!
    SDA SRS 2.3s
    Pair of Carver TFM 35s
    Carver C-1 Preamp
    CAL Icon MkII CD
    RTA 12s, need major work
  • I recently used Loctite Red, and that appears to be perfect as I could see it wick into the space between the magnet and plates, but no so far as to reach the VC.
  • TennManTennMan Posts: 994
    I recently used Loctite Red, and that appears to be perfect as I could see it wick into the space between the magnet and plates, but no so far as to reach the VC.

    I hope it works for you but I think you used the wrong product for the job. Red Loctite isn't intended to be used as a glue. It only gets hard in the absence of air.
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  • FestYboyFestYboy Posts: 2,193
    TennMan wrote: »
    I recently used Loctite Red, and that appears to be perfect as I could see it wick into the space between the magnet and plates, but no so far as to reach the VC.

    I hope it works for you but I think you used the wrong product for the job. Red Loctite isn't intended to be used as a glue. It only gets hard in the absence of air.

    Correct. You use red Loctite when repairing a shifted magnet as a replacement for the factory adhesive between the pole plate and magnet surface.
  • lawdogglawdogg Posts: 268
    edited February 20
    You could use a 2-part epoxy. Under destructive testing conditions, I have gotten Loctite Powergrab to shift after it hardened, and not 2-part epoxy.
    <3 my 3.1TLs

    I will fix your shifted magnets for free. :)
  • TennManTennMan Posts: 994
    I did mine with JB Weld. I think you could drop them out of an airplane and they wouldn't move. They probably don't look as nice as they would have with the other products.
    SDA 2BTL · Sonicaps · Mills resistors · RDO-198s · New gaskets · H-nuts · Erse inductors · BH5 · Dynamat · Crossover upgrades by westmassguy
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  • For indestructability, I like JB Weld too and have used that more than anything. It definitely is a little tricky to work with until you're used to it. I usually don't mix up more than a teaspoon worth at a time and apply it with a small stick like a bamboo skewer. The magnet attracts it because it contains metal particles, so you have to be a bit careful with the angle of attack, so to speak. It cleans up pretty well with Goof-Off. Some people just dab it at compass points, but I have always gone full circle because I'm a ****.

    Here's a pic of the JB Weld finished product... sorry it's not bigger.

    2n9evoi907ow.jpg


    I've used Loctite PowerGrab too. It's MUCH easier to work with, and it seems secure enough that I wouldn't ever be worried about it failing during normal use, nor even if the drivers were well packed for shipping. The only thing I've wondered with that is would it ever become brittle and less effective with age?
  • ... Some people just dab it at compass points, but I have always gone full circle because I'm a ****.

    Hmmm... odd that the naughty word list apparently includes "mass-oh-kissed".

    All the freaky discourse here has really got us on linguistic lockdown. :D
  • pitdogg2pitdogg2 Posts: 9,657
    edited February 21
    "I've used Loctite PowerGrab too. It's MUCH easier to work with, and it seems secure enough that I wouldn't ever be worried about it failing during normal use, nor even if the drivers were well packed for shipping. The only thing I've wondered with that is would it ever become brittle and less effective with age?

    I too have used both. I can tell you with certainty that JB weld will shatter easily. I do not think one is better than the other when it comes to this use.

    I have had to remove it and it will come off like it wasn't even there. It wasn't on a speaker but it was on metal and it will pop right off. I do not know how some say "it saved my engine" I have always been skeptical of that claim.

  • F1nutF1nut Posts: 39,478
    Ivan, that's been my experience with JB Weld. Personally, I think it is worthless.
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."


  • On3s&amp;Z3r0sOn3s&amp;Z3r0s Posts: 1,013
    edited February 22
    pitdogg2 wrote: »
    I too have used both. I can tell you with certainty that JB weld will shatter easily. I do not think one is better than the other when it comes to this use.

    I have had to remove it and it will come off like it wasn't even there. It wasn't on a speaker but it was on metal and it will pop right off. I do not know how some say "it saved my engine" I have always been skeptical of that claim.

    I couldn't tell from that if you've had it shatter or otherwise fail on a MW? I've had it crack on me in other applications. But the magnet actually sucks it into the crease where the magnet and pole plates meet. After applying that on the entire circumference both top and bottom I can't imagine what kind of force the driver would have to sustain before the magnet would move. I'd think you'd be way more likely to crack the magnet or have a failure with the union at the driver frame first.

    But then, I'd also be curious what the destructive testing conditions were that @lawdogg used to get the PowerGrab to fail. I hope y'all aren't doing drop tests with working MW's. I'm all for science, but not to the point of sacrilege.
  • pitdogg2pitdogg2 Posts: 9,657




    pitdogg2 wrote: »
    "I've used Loctite PowerGrab too. It's MUCH easier to work with, and it seems secure enough that I wouldn't ever be worried about it failing during normal use, nor even if the drivers were well packed for shipping. The only thing I've wondered with that is would it ever become brittle and less effective with age?

    I too have used both. I can tell you with certainty that JB weld will shatter easily. I do not think one is better than the other when it comes to this use.

    I have had to remove it and it will come off like it wasn't even there. It wasn't on a speaker but it was on metal and it will pop right off.

    I do not know how some say "it saved my engine" I have always been skeptical of that claim.


    It was not on a woofer. I have used it on dozens of woofers and not once did I have it get sucked in between the two.

    When I had to remove it from something to do over or just to remove is where I found it shattered.
    Search Mythbusters they had a whole show where it was featured for welding and fastening metal.

    IT FAILED MISERABLY

  • I used to use jb weld all the time on engine cases. Dirt bikes in specific, the bolt that attaches the kickstarters would wear through the case from being the wrong bolt or whatever the case may have been. I would clean it up real good and jb it. Of course afterward the same bolt or kicker arm would hit the jb weld thousands of times and scratch it up but never failed or leaked. Maybe the engine heat cycling would play a part in hardening it or softening. Either way I never had one shatter or had to do it twice. On another note I use power grab on my magnets, It's just to easy
  • lawdogglawdogg Posts: 268
    But then, I'd also be curious what the destructive testing conditions were that @lawdogg used to get the PowerGrab to fail. I hope y'all aren't doing drop tests with working MW's. I'm all for science, but not to the point of sacrilege.

    Yeah they already had bad voice coils. I dropped them from shoulder height onto bare concrete garage floor. And also hit them with a 5lb hammer against the edge of my work bench.

    And for what it's worth, I've completely abandoned JB Weld for adhesive purposes after it failed on me at a 100% failure rate in other applications with similar objectives (e.g., holding together a broken aluminum BMW mirror bracket).
    <3 my 3.1TLs

    I will fix your shifted magnets for free. :)
  • lawdogg wrote: »
    And for what it's worth, I've completely abandoned JB Weld for adhesive purposes after it failed on me at a 100% failure rate in other applications with similar objectives (e.g., holding together a broken aluminum BMW mirror bracket).

    I guess I'd dump it too if I had that kind of luck with it. I've had it fail twice that I can think of (out of probably 40-50 uses) in situations where there was enough flex and vibration that I think anything that hardened brittle would have failed. I've wondered before when working with small amounts how much a difference in the ratio of the epoxy / hardener would affect performance over time.
  • audioluvraudioluvr Posts: 381
    edited February 27
    lawdogg wrote: »
    Yeah they already had bad voice coils. I dropped them from shoulder height... I've completely abandoned JB Weld for adhesive purposes after it failed on me at a 100% failure rate in other applications with similar objectives

    ^^^^ He was the gorilla in the Samsonite luggage commercial...
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  • Rrusse11Rrusse11 Posts: 116
    " I've wondered before when working with small amounts how much a difference in the ratio of the epoxy / hardener would affect performance over time."

    Too much of either weakens the bond, uncatalysed resins tend to remain plastic.
    For quality work, a scale is called for.
    SDA SRS 2.3s
    Pair of Carver TFM 35s
    Carver C-1 Preamp
    CAL Icon MkII CD
    RTA 12s, need major work
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