Coating for bare steel wire?

In article , Winston writes

Snip

I suspect that the insulating coating doesn't have to be perfect. Just a thin layer of oxide would do the trick -after all the contact area between the bundled wires is quite small. I noticed in the 'JP Transformer' book that someone kindly posted the URL for that one method used was to phosphate coat the iron. So just use one of the phosphoric acid 'rust treatments' to give a thin coat of phosphate.

Winston wrote: I have a query into a supplier of ferromagnetic tape suggested

Tempel Steel sells it in coils. I have called the application engineering departments of many companies, explained a problem and had the applications guy sample me the quantity I needed. If all else fails, why wouldn't you stack some thin mild steel sheet to the required thickness, clamp it down and mill out the core shape you want? Dip each new lamination in thinned laquer, restack, and you are good to go. If you described the function of what you have in mind, (I'm seeing a giant 60 Hz tape recorder head), perhaps some of the fellows could offer more suggestions.

Kevin Gallimore

Excellent! That is a whole lot less trouble than the method I contemplated.

Thanks, Chris.

--Winston

I will check with them.

Maybe if I spoke nicely with Tempel? Good idea!

That'll work, especially if I could get my hands on some silicon steel sheet or the tape you mentioned. Obviously, I could use regular old HRS as well.

You intuit well. I hope to shrink small sheet metal dents from the 'accessible' side.

--Winston

(...)

Like this:

--Winston

On Thu, 08 Oct 2009 14:04:33 -0700, the infamous Winston scrawled the following:

You're going to snatch those Big Wheels right out from under those noisyarse little bitty bastids, aren't you? Excellent!

ENGAGE!

Try

. They used to provide -anything- in hardware to us when I worked at Southcom. (No, not the military one. SCI, which was snatched by Loral in the late '70s)

Um, you're really building yourself a ten-incher? Crikey! Your sales will go into the millions within weeks if it works. And women; there'll be lots and lots of women.

-- Adults are obsolete children. --Dr. Seuss (Theodore Geisel, 1904-1991)

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On Thu, 08 Oct 2009 16:07:40 -0700, the infamous Winston scrawled the following:

OK, cool (but not nearly as cool as an electronic 10-incher.)

My across-the-street neighbor can use one of those right now. He backed into something and rolled a dent into the left rear QP. I told him to find a local "paintless dent removal" shop, guys who use suction cups and balloons to pop panels back into shape. I guess they also can use this type of technology nowadays.

Is this called induction shrinking?

-- Adults are obsolete children. --Dr. Seuss (Theodore Geisel, 1904-1991)

--

On Thu, 08 Oct 2009 16:07:40 -0700, the infamous Winston scrawled the following:

So, you're hoping to save yourself $2,300, eh?

-- Adults are obsolete children. --Dr. Seuss (Theodore Geisel, 1904-1991)

--

(...)

Curses Pinky! My true plan for world domination is revealed!

No hits for 'core' 'solenoid' or 'iron'. Oopsy.

Just call me Dr. Degauss

Thanks!

--Winston

(...)

Mine will *hum*.

Could be! Hope there is no frame damage.

Dunno. I expect it's equal parts induction heating and attraction. (Can't wait to find out how you riff on that!)

--Winston

Wowser! I had no idea.

Interesting. Thanks!

--Winston

On Thu, 08 Oct 2009 22:20:25 -0700, the infamous Winston scrawled the following:

So teach it the words, wot?

Nah, it barely scratched the paint at the 90-degree rear flange, where the taillight goes in.

Sexshull fulfillment. Got it.

-- Seen on a bumper sticker: ARM THE HOMELESS

On Thu, 08 Oct 2009 22:21:39 -0700, the infamous Winston scrawled the following:

To be fair, you're only building the $209 induction probe.

-- Seen on a bumper sticker: ARM THE HOMELESS

On Thu, 08 Oct 2009 22:16:41 -0700, the infamous Winston scrawled the following:

But 14 pages for "ferromagnetic tape". Doesn't that count?

Well, Edgar Degas prolly got some wimmenz, too.

-- Seen on a bumper sticker: ARM THE HOMELESS

(...)

I see copper tape and aluminum tape. Nothing remotely ferrous. Must be going blind... :)

--Winston

For silicon steel sheet, check

site says that they will deal with prototype quantity orders.

You might be able to talk these guys out of a small amount of raw material

you live in the LA area, a stop in person might be most successful

Ditto these guys:

Whether using wire or laminations, don't worry about splicing or joints. Just get them close, a few thou of gap won't matter. The open air gap on the "working end" of your device will dominate the reluctance of the assembly. Even when shunted by sheetmetal being de-dented, the sheetmetal will very probably saturate.

(...)

I shall check into these sources.

We agree on all that.

The 'splice' issue was purely mechanical. I had a jig set up to wind the 'laminations'. It needed a continuous length under tension in order to work properly (or at all). I didn't see how I could stop the winder and start with a new end of steel wire without the whole thing turning into a birdcage (if I did not splice).

The laminations had a tight fit in the insulating tube as it was; a splice probably would have prevented the thing from going together.

Thanks, Don!

--Winston

If your doing dent pulling It would be better to use Direct Current on the magnet.

If you are heating the metal then you need to use AC.

If you use DC then you don't need to use wire or laminations for the core. Simple solid Iron would do. And DC is easy to get, all you need is four diodes in a bridge arrangement and a source of AC.

Bill K7NOM

W>

We agree on all that. I conjecture that most of the 'dent pulling' occurs as a function of eddy current heating in the sheet metal. It's a happy coincidence that both the heating and the magnetic force are in aid of each other.

Thanks!

--Winston