Re: [EE] Small electromagnet cores?

Fair enough.

Stainless steel is mostly non-magnetic and won't help you here.
Most any grade of mild steel should be fine. I'm sure there's details
about alloys, but they're within a few percent of each other.
Screws and nails from the hardware store are an easy place to start.
Avoid stainless. Be sure a regular permanent magnet will pick them up.
As a reference at least, these nails seem about the right shape and
close to the size range you're looking for:
https://www.amazon.com/Hard-Find-Fastener-014973212032-Finishing/dp/B00L1IVS1U
But at least here in the USA, I would expect to pick up a 1 Lb box of
them from any hardware / home store for about the price of a Starbucks
coffee.

-Denny


On Mon, Jun 2, 2025 at 11:25 AM Mike Hord <[email protected]> wrote:
>
> Er, ignorance?
>
> The problem is, online metal sellers want me to specify an alloy, but I'm
> not sure which of the many to choose. Finding a small enough rod is
> difficult as well.
>
> I don't want to buy a bunch of stuff to throw at the wall and see what
> sticks, but I may end up doing so.
>
> Just ordered some 3mm 1015 from Online Metals... It was cheap enough to be
> worth the experiment.
>
> Mike
>
>
> On Mon, Jun 2, 2025, 12:08 PM Denny Esterline <[email protected]> wrote:
>
> > I may be misunderstanding something, but why not just use a mild steel
> > rather than stainless?
> >
> >
> > -Denny
> >
> > On Mon, Jun 2, 2025 at 10:52 AM Mike Hord <[email protected]> wrote:
> > >
> > > Hey all-
> > >
> > > I'm trying to make a flip-dot display like this one:
> > > https://hackaday.com/2021/05/29/3d-printed-flip-dots/
> > >
> > > I'm having a hard time with the electromagnet component of the project.
> > OP
> > > used 3mm threaded rod, and it seemed to work okay per his videos, but
> > it's
> > > not working for me at all.
> > >
> > > I'm relatively sure the problem is in the permeability of the core.
> > > Stainless steel is not a great magnetic field conductor. I'm looking for
> > > something better.
> > >
> > > Lots of searching has led me nowhere. I'm thinking of trying a nail next;
> > > I'm wondering if anyone has any better ideas for a core? NB- I've seen
> > the
> > > "soft iron core" that Amazon sells; it's a bit expensive for my taste
> > ($16
> > > for 200mm; I would need four of those rods to complete the project).
> > >
> > > Mike
> > > --
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