potting inductors

[Deward Hastings]

Thomas:

Do you bother to “pot” or bond when you wind inductors, either by brushing between layers or “dip and drip”? I used to brush, but my Glyptal stash is long gone, I see it’s $40 a quart now, and I don’t believe I’ve used more than a pint or two in 40 years. So that’s not happening. Maybe a urethane varnish? I’m realizing that I don’t even know what they use to “enamel” enameled wire any more, or if there’d be a compatibility problem . . .

[ThomasW]

Hi,

Nope IMO potting is way too much hassle.

The 'heavy' hydro-coated wire I use with my winder is virtually bullet-proof, so nothing short of acid is going to dissolve that coating.

North Creek 'pots' their inductors by dipping them in epoxy. That's probably the easiest thing if one is so inclined.

[Deward Hastings]

Epoxy would work, and I think I have some West System leftovers around somewhere (the stuff does last forever). But "hassle" and overkill do come to mind. I've got some not-too-old Varithane on the shelf . . . maybe I'll try that. As long as it sets up it can't hurt anything . . .

[JonP]

Ahhh... brings back memories of a power inverter company I worked for, where they wound and potted most of their inductors. Some pretty big stuff, too. We're talking dunking in a vac tank of varnish, and baking in an oven, up to 12"x12" E I core inductors or transformers... Way overkill for speaker inductors.

Basically, you're looking for something to act as a glue, mostly doesn't matter what it is, except for it dissolving or reacting badly with your wire insulation.

Try some test paintings of that Urethane on your wire.... Or, just wind tight and use a ton of tie wraps.

[Deward Hastings]

> We're talking dunking in a vac tank of varnish, and baking in an oven

Relatively easy now for the DIYer . . . poly bags for the impreg tank and borrow the "foodsaver" for the vacuum. If you measure the juice right it all just "disappears" into the "widget". Cure it in the powder coat oven. Haven't tried it on coils, though.

I've done fiberglass in vac bags . . . it's the only way I know to get a really dry layup and complete coverage at the same time.