Making one's own XFO cores?

Thread Starter


Joined May 16, 2005
I'd like to experiment with potted cores as part of my induction-heating experiments. I cannot justify the expense of having them custom made.

Has anyone here made their own powdered iron cores?

Is it just a matter of mixing up epoxy and iron filings? Or do unexpected pitfalls lurk?


Joined Jul 17, 2007
More power to you, Brother.

No, I have not made powdered iron cores myself.

I know JUST enough about the process to get myself into a whole heap of trouble with anyone who wants to take a potshot at me. So be it.

There is a somewhat obscure process that is known as "ball milling". The material to be reduced is chopped into small chunks, and then fed into a ball mill, which holds the material in a liquid suspension. The "balls" in this mill are made of various sizes of ceramic material, which systematically reduce the small chunks into microfine powder, which is eventually separated out of the fluid medium through whatever means; magnetic, centrifugal, etc.

Other materials are introduced to the mixture in porportion to arrive at the end goal, whatever the critera are to reach it.

There are many different "standard" materials for cores. I won't even begin to pretend that I know what they are, except somewhere along the way, there has to be a bit of iron SOMEwhere.

It will be extremely difficult to ensure any kind of consistency, with tools available to laypersons.

Even commercial toroids vary widely in quality.

Even supposedly hermetically sealed toroids suck up moisture like sponges, drastically changing their electrical properties.

But if you have a way of suspending small pieces of iron in a fluid medium, grinding them to micron-sized dust, separating them out afterwards, and somehow dispersing the iron dust evenly in an epoxy mould - more power to you.

I most certainly don't want to discourage you. However, I would not want you to go broke trying to make "the perfect toroid".

That's my answer and I'm stickin' to it.