Is JB Weld is the only thing available for preventing magnet shift?

Mystery

Recently, I'm cleaning (well, trying to) my basement as I had lot of free time.
I had couple of monitor 4's, 4.5's etc... tucked in the corner in basement.
I remembered all of them were working when I stored them few years ago.
Now, two of them woofers have the stupid dreaded magnet shift and makes tweeter like sound with no movement.
So pissed off! What a waste! Hope Polk is using better glue on their newer models.
Anywho, now I need to keep others from the same fate.
Is JB Weld the only thing? If yes, which type of JB weld is good for magnets?
This cold-weld steel reinforced?
https://www.amazon.com/J-B-Weld-8265S-Cold-Weld-Reinforced/dp/B0006O1ICE/
or Kwik-weld?
https://www.amazon.com/J-B-Weld-8276-KwikWeld-Reinforced/dp/B0006O1ICY/
or Steelstick putty?
https://www.amazon.com/J-B-Weld-8267-S-SteelStik-Reinforced/dp/B000786GLM/
...
What about two part epoxy or metal epoxy that Harbor Freight sells?
Any other recommendation?

pitdogg2

Power grab heavy duty water clean up tube is what I used.

https://www.menards.com/main/paint/adhesives-glue-tape/adhesive/construction-adhesives/loctite-reg-power-grab-reg-express-heavy-duty-construction-adhesive-9-oz/5202620/p-1444432350191.htm

Jazzhead

I used PC-7 epoxy. It's thick enough (at room temperature) that you can blade it on without mess/sagging. It's bombproof once it cures.

Gardenstater

I used this stuff and would use it again. It adheres tenaciously to metal and ceramic/glass and I like that it is clear. One drawback is it only seems to come in the large tube. I squeezed (squoze?) it into a syringe to make it easier to apply, especially to back edge of magnet. Doesn't shrink a lot but does some, through solvent evaporation.

There's so many suitable choices!

Mystery

But how do you know if that prevented magnet shift?
Some drivers never shift whether you epoxy glue or not.
Did anyone test after applying epoxy by dropping or shaking the speakers or something in that manner?
Or is it just a trust on whatever glue you chose?

VR3

Not sure I would recommend shaking or dropping speakers, ask @treitz3

Mystery

VR3 wrote: »

Not sure I would recommend shaking or dropping speakers, ask @treitz3

I know. What I was saying was for test purposes if anyone did a test with any drivers using different glues to confirm if they prevent magnet shift or not.
Doesn't make sense to drop the one you just put epoxy on from a nice speaker.
This issue came like 15-20 years ago and just wondering if anyone tested glue/epoxy properly or not with test speakers.
Even someone who put certain epoxy and had a bad drop or accident that pretty much guaranteed magnet shift but didn't also would help.

pitdogg2

One thing is for sure, if you do not use it you can come home to a shifted magnet having never dropped or bumped. All this is doing is helping whatever adhesive is left under the magnet to not allow it to shift to the best of our ability. It will be much harder for the magnet to shift if it must jump this barrier we put around the magnet. Can it still shift if it's dropped sure it can.

Mystery

pitdogg2 wrote: »

One thing is for sure, if you do not use it you can come home to a shifted magnet having never dropped or bumped. All this is doing is helping whatever adhesive is left under the magnet to not allow it to shift to the best of our ability. It will be much harder for the magnet to shift if it must jump this barrier we put around the magnet. Can it still shift if it's dropped sure it can.

Okay so there is no official or non official test done.
I think around 10 years or so ago I did apply two part epoxy on few Polk drivers but those speakers are long sold.

But looking at the recent magnet shift on the speakers, I'd epoxy any vintage Polk I run into.
In conclusion, put something, doesn't matter what, as long as it's epoxy or metal weld to help prevent magnet shift and cross fingers.

Mystery

pitdogg2 wrote: »

Power grab heavy duty water clean up tube is what I used.

https://www.menards.com/main/paint/adhesives-glue-tape/adhesive/construction-adhesives/loctite-reg-power-grab-reg-express-heavy-duty-construction-adhesive-9-oz/5202620/p-1444432350191.htm

Hmm... That's much cheaper than the epoxy.
Does this work as good as JB Weld for metal like magnets?

pitdogg2

I feel it works better it's much easier to get in the magnet spaces you can build it up easier it doesn't run. You just caulk a big bead around your magnets and then you smooth out with your finger press it in and smooth it down and it it locks everything in place. it's well regarded here a lot of us have started using it I did JB weld on my first ones I'll never use it again.

Mystery

pitdogg2 wrote: »

I feel it works better it's much easier to get in the magnet spaces you can build it up easier it doesn't run. You just caulk a big bead around your magnets and then you smooth out with your finger press it in and smooth it down and it it locks everything in place. it's well regarded here a lot of us have started using it I did JB weld on my first ones I'll never use it again.

Okay, I just read the description and it does mention metal but says at least one of the surfaces must be porous.
Is Polk magnet or frame porous?

pitdogg2

Do a search we've been over this time and time again. It works and holds or you can keep going over and over it in your head forever.

xschop

I use Power Grab in the hand tube. I've even had to glue SL5000 tweeter magnets with good results.

lawdogg

Mystery wrote: »

Okay so there is no official or non official test done.
I think around 10 years or so ago I did apply two part epoxy on few Polk drivers but those speakers are long sold.

But looking at the recent magnet shift on the speakers, I'd epoxy any vintage Polk I run into.
In conclusion, put something, doesn't matter what, as long as it's epoxy or metal weld to help prevent magnet shift and cross fingers.

I did my own destructive testing (throwing them on the concrete garage floor) and found Loctite power grab shifted very easily. I've only used epoxy ever since and epoxy has never shifted.

Mystery

lawdogg wrote: »

Mystery wrote: »

Okay so there is no official or non official test done.
I think around 10 years or so ago I did apply two part epoxy on few Polk drivers but those speakers are long sold.

But looking at the recent magnet shift on the speakers, I'd epoxy any vintage Polk I run into.
In conclusion, put something, doesn't matter what, as long as it's epoxy or metal weld to help prevent magnet shift and cross fingers.

I did my own destructive testing (throwing them on the concrete garage floor) and found Loctite power grab shifted very easily. I've only used epoxy ever since and epoxy has never shifted.

Yes thanks.
I'm leaning towards epoxy but thinking if Loctite PL Max is better.
It mentions metal and stainless steel.
I have about a dozen and I think 3 of them are frozen.

https://www.loctiteproducts.com/en/products/build/construction-adhesives/loctite_pl_premiummaxconstructionadhesive.html

lawdogg

Good luck and enjoy the process! I'm sure you'll be able to get it done!

audioluvr

I use Loctite Powergrab Ultimate. I tested it by throwing my speakers out a second floor window. Still play great but they look like hell

VSAT88

I used nothing at all early on and ...Magnets shifted.

Mystery

VSAT88 wrote: »

I used nothing at all early on and ...Magnets shifted.

Of course that's why the thread is here.
Question is about what to use among many choices.

Gardenstater

I think if one didn't want to use epoxy or what I suggested above for whatever reason (mess, don't have any handy etc), one could use this prior to filleting in with some other adhesive as a 2nd insurance at a later time:

audioluvr

Polyurethane isn't really that strong IMHO. You want something that bonds/ welds everything together. I would test it by placing two pieces of scrap metal together then running a bead around the perimeter. Once cured try to get the two pieces to move

Gardenstater

The one I last brought up is a type of super glue (cyanoacrylate). The one Mystery was speculating about is a Silane (SiH4) Modified Polymer, which combines the highly elastic properties of Silicone with high mechanical strength of Polyurethane. Not sure I would want to use anything that is elastic where you want to protect from dislodgement due to impact.

bigmontana

I recently used Loctite Instant Mix epoxy to do the magnets on my 2B's. It was readily available and I found it easy to apply cleanly. I used maybe half of the 14ml tube to do 4 magnets, so I would expect you could get 8 to 10 out of it. That was also applying a full bead all the way around the magnets, which in hindsight was probably overkill.

hytekrednek

only the one side of magnet is epoxied, correct? I saw the pic here of one done that had glue on both sides of the magnet. That look to be very tough to do without making a huge mess.

Gardenstater

Both sides, without a doubt. You can do one side, let it cure a bit, then flip the speaker over and do the other side, so gravity works for you instead of against you.


bigmontana - I'm glad you chimed in because I think that stuff may be ideal and I forgot who had posted it before.

https://www.ebay.com/p/536442390

bigmontana

The static mixer that comes with the Instant Mix epoxy makes it easy to get to the bottom side of the magnet.


You do have to work somewhat quickly or the epoxy will start to thicken inside the mixer. Don't stop for a break until you're completely done!
I did the top side of all four magnets and then immediately did the bottom sides starting with the first one again. No issues with dripping or slumping.

I was able to find it at my local Target: https://www.target.com/p/loctite-47-fl-oz-epoxy-5-min-instant-mix/-/A-14767197#lnk=sametab

hytekrednek

very helpful! Thank you

drumminman

I used JB Weld original formula for all the mw’s in my 2.3tl’s, RTA-12c’s and CRS+’s and had no issues. It takes a while to dry, but it will not fail.
I had a good supply of nitrile gloves and paper towels on hand to immediately remove any excess.

TennMan

I used JB Weld. I have no doubt about it's strength but it was messy to apply. If I had it to do again I would use clear two part epoxy.

Mystery

Okay I went back to what I used 8 years ago, two part epoxy.
It hardens like rock and when it is applied at multiple places, even if it's not adhesive like original glue, it'll block movement.