What kind of glue for magnet onto P90 bobbins

[Yves]

What kind of glue are you using to attach alnico bars to P90 plastic bobbins ?

I've been using Super Glue so far, but:

- It's hard, so not meant to be taken apart (for magnet charging purpose or whatever) except ...
- even too hard maybe, i.e. brittle: I had some P90 the other day (without keeper bar, that is with the mounting screws touching the magnets): when I mounted the pup, one mounting screw sort of turned into some kind of lever by touching one bar and detached it. This may have happened as well with some other glue, but I feel a softer glue may help to "adjust space" in such an event and, on the other hand, allow the removal of the magnet when required.

Thanks,
Yves.

[Possum]

....

just use a little bit of double stick tape to keep the magnet in place. Super glue isn't really permanent, some of my early pickups where I made the bobbins out of forbon and superglued the magnets to the forbon have fallen apart, the glue doesn't really grab alnico over a long period of time....

[Sweetfinger]

Use Liquid Nails construction adhesive. It is available in a smaller tube for "home" use, or try a silicone sealer for a less permanent but still flexible bond

[defaced]

In the stuff I've done for a different hobby, silicone doesn't hold too well to most plastics. I'd do a test piece and try it. The best silicone I've found that's easy to get ahold of is GE Silicone I. The stuff works great for aquariums and glass in general but not so great for other materials.

Liquid Nails which is a polyurethane based adhesive (like Great Stuff and Gunilla Glue) is usually better at bonding to plastics, but it's still hit and miss.

If the bobbins are made of polypropylene (I don't know if this is a common material or not), you'll have a hard time finding something that'll stick to it, or at least I have. I think I've tried nearly every common adhesive and they all pretty much stink at adhering to PP.

[Joe Gwinn]

In the stuff I've done for a different hobby, silicone doesn't hold too well to most plastics. I'd do a test piece and try it. The best silicone I've found that's easy to get ahold of is GE Silicone I. The stuff works great for aquariums and glass in general but not so great for other materials.

Silicone adhesives are very sensitive to grease. Even a fingerprint will prevent bonding, and so it can be hard to get and keep things clean enough. At minimum, one must acetone wipe and dry surfaces to be bonded.

Liquid Nails which is a polyurethane based adhesive (like Great Stuff and Gunilla Glue [Gorilla Glue?]) is usually better at bonding to plastics, but it's still hit and miss.

Less sensitive to grease, but still needs things to be clean.

If the bobbins are made of polypropylene (I don't know if this is a common material or not), you'll have a hard time finding something that'll stick to it, or at least I have. I think I've tried nearly every common adhesive and they all pretty much stink at adhering to PP.

There are adhesives for polypropylene, but not ones found in hardware stores.

[David Schwab]

I would wipe with naphtha or MEK.. the second one not being as common, and it's nasty stuff.

But those are standard for degreasing when getting ready to spray finish.

[jrfrond]

Try LocTite 410. It is a rubber-impregnated CA formula. In the music industry, it's extensively used for speaker reconing (that's mainly what I use it for). When you see the black ring of adhesive around a speaker dust cap, LocTite 410 is what you are looking at. It's dyed black to differentiate it from normal non-rubber glues, but it is strictly cosmetic. This adhesive is permanent with excellent shear strength, but is not as brittle as traditional CA adhesives and can be sliced-off for rework. It also cures somewhat slower, so you have some positioning time (unless you flash-cure it with accelerator) and is high-viscosity, so it is gap-filling.

LocTite 410 is pricey, so I get a clone from a company called NHP Adhesives. I purchase it direct in 8oz. bottles (it goes fast with reconing, especially on 18" drivers), but you can also get it here, from BP Hobbies in Piscataway, NJ:

http://www.bphobbies.com/view.asp?id...32&pid=S915023

Oh yeah, works great for pickups too. Because it is not solvent-based, it won't attack and craze plastic bobbins.

[Yves]

Thanks for the advices: both Loctite 410 and double stick tape look like interesting solutions to me.
The double stick tape being more easily "undoable", which is a nice feature for recharging magnet for instance, should it be needed.
Have to try these.