Coating for bare steel wire?

Winston wrote: ...

Magnet wire. E.g., from a MOT. Bob

Of no use, but interesting as all getout:

Dave

(...)

Downloaded and saved. Very interesting indeed. Thanks, Dave!

--Winston

I dont read Arabic very well. Is there a translation available?

GUNNER'S PRAYER: "God grant me the serenity to accept the people that don't need to get shot, the courage to shoot the people that need shooting and the wisdom to know the difference. And if need be, the skill to get it done before I have to reload."

Transformer Iron cores depend on Iron with a Oxide surface (black). I don't know if your MIG wire is suitable for that treatment.

Bill K7NOM

W> Hi all,

How about a single pass using a UV curing coating?

What do you need to make that can't use a tapewound core?

Kevin Gallimore

The MIG wire is >97% iron so I'm hoping that will be sufficient. I suppose the oxide surface acts as an electrical insulator to limit eddy current flow between laminations. For the prototype, varnish would take that role.

Thanks!

--Winston

I didn't see that in Mcmaster or Enco. Is that something I can pick up easily & cheaply? I DAGS on '"uv curing" coating' but didn't come up with a retail outlet. Suggestions?

Envision a really long 'E' core. I want a lot of flux concentrated between the center pole piece and the two outer pole pieces. Figure ca 10" long with a 1" diameter center pole.

Thanks!

--Winston

Depends on what you are making -- relay, transformer, choke, electromagnet, vibrators for friends and loved ones, etc. Also on form factor. Which of the shapes in following is closest to what you want?

Most of those shapes are commercially available, some in lower-conductivity silicon steel laminations like in most commercial transformers, others in ferrites or powdered iron.

One light coating of polyurethane on your wire probably would be good enough. Have you thought about hanging the wire between two well-separated trees outdoors and painting it with a roller? Didn't think so. :) But seriously, if you string the wire back and forth 10 or 20 times between two headers 40' apart, it would be quite fast to paint it all with a roller.

also may be of interest re finite elements magnetic modeling.

James Waldby fired this volley in news:nZ6dne2Ge5jWrVDXnZ2dnUVZ snipped-for-privacy@bresnan.com:

It's a lot easier than that. The old Fordson spark coils of tractor mythology/fame used "stove pipe wire" for the core.

The trick is to anneal the wire in a slightly oxidizing fire (basicall, "blue" it). The oxide coating is not significantly conductive. And for what it's worth, the more thoroughly annealed the wire is, the greater the permability and the higher the saturation current of the transformer will be. Of course, the alloy plays a great part in this, with high- silicon steels being good in this respect.

LLoyd

I would probably call Master Bond.

Wouldn't be easier to make it from tape? Higher density and your choice of magnetic materials, from amorphous to grain oriented silicon.

Kevin Gallimore

Check the second URL (quoted below). It gets you a PDF file in English -- with the sole nuisance that there is an '&' in the file name, which unix and linux need special command-line tricks to deal with.

First publication 1925, last shown in the usual information is

Total file size is 5.8 MB.

Enjoy, DoN.

Thanks!

At one time I started teaching myself Arabic but lost interest before long.

Gunner

GUNNER'S PRAYER: "God grant me the serenity to accept the people that don't need to get shot, the courage to shoot the people that need shooting and the wisdom to know the difference. And if need be, the skill to get it done before I have to reload."

You guessed it! It's an electromagnet.

The 'ER' core is the closest. Unfortunately I need all pole pieces to be about 4 times longer than we see in the illustration.

Yup. My application is at 60 Hz so I don't really need ferrites. That is fortunate because this requires a 'full custom' treatment. The tooling charge would probably be awe - inspiring.

Funny you should mention that! I used a very similar method to coat the copper windings. They've been suspended in the back yard drying for the last few days!

Hmmm. Perhaps a tubular roller on both ends so that I can coat the unexposed side as soon as most of it is dry.

Food for thought.

Very cool! I will play with that.

Thanks, James!

--Winston

(...)

Interesting!

I shall DAGS 'stove pipe wire' ASAP.

Thanks, Lloyd!

--Winston

OK. Thanks!

I will DAGS on this concept ASAP. I was completely unaware that the ferromagnetic material was available in tape form.

Thanks, Kevin!

--Winston

And steel is 99.9-99% iron. It's the little details that will get you. My old, OLD electrical how-to from the teens and twenties shows them using iron, not steel, wire for solenoid cores. The reason being is that soft iron, not steel, wire will have little or no remaining field once the current is turned off. You want it magnetized only when the current is on. And eddy currents are only there if you're running AC through it, which sounds like some kind of choke, if that's what you're doing. In which case you might want to rethink your choice of magnetic core. At 60 Hz or so you can salvage the silcon iron out of old transformer cores. Insulate with varnish, the induced voltages are low. For higher frequencies, hit one of the remaining ham radio supplier sites and look for powdered iron or ferrite cores, they have much better properties at higher frequencies. Then you need a book to tell you the formulas to get the performance out that you want with the magnet parameters of those cores.

Stan

I do not understand your concern about splices. I do not think it will make a noticeable amount of difference if you have a few breaks in the wire rather than a continuous length.

Dan

(...)

I DAGS on 'iron wire' and 'steel wire'; came up with bupkis.

Yup. A.C. electromagnet is what I'm building.

I'd really like some enamel insulated iron wire, but none of my sources carries it. I have a query into a supplier of ferromagnetic tape suggested by Kevin Gallimore but I'm concerned that they deal in much larger quantities than I need. I'm not expecting a response from them.

MIG wire is the nearest thing available.

Suggestions?

Not really. This is a 10" long part. I'm not going to spend a few hundred dollars for transformers to disassemble.

I've looked into those and discovered they measure just a few percent of the size that I need and don't have nearly the proper geometry or chemistry. They are perfect, otherwise.

Thanks Stan.

--Winston