Large or large-ish coil winding forms?

xanatos

I'm back after completing a three month programming project and looking to play a little before I dive into the next project!

I'm looking for some coil forms - I want to make a few Maxwell Coil arrangements as a side project - I'm looking for a source of nice circular coil forms in the 3 to 5" diameter range, and a few more in the 7 to 9" range, where the channel of the form would be around 1/4 to 3/8" thick... these can be plastic, as they will be subject to no significant heating, it's for me to do some playing with forming more complex fields, magnetic bottles, etc.

I searched for coil forms, large coil forms, etc., and have not had exactly stellar results. Mostly little ferrites & torroids, mostly RF stuff. I'm just wondering if anyone on here has a bead on anything similar.

If worse comes to worst, I can always cut out a bunch of circles & make a bunch of cross-connects to hold the two together and give me something to wind on, but the forms I have in mind I see in USE everywhere, but can't seem to find where people are actually getting them.

See image below for ideal form.

Thanks for your help/advice,

Dave

Yanomani

Hi xanatos

I'm unsure if it can fit your needs, but if you could find some ancient Super 8 film reels, I'd bet they can spare you from scratching your head a lot.

The following link lists the available diameters for the various reel types.

http://www.filmfix.com/super-8-normal-8-spule-erkennung-format.asp?l=e

Hope it could help a bit

Yanomani

Lawson

I would expect a random selection of cardboard tubes and boxes could be cut into useful coil forms. Wouldn't have sides without extra work, but if the forms are wide enough, sides may be optional. I'd also expect plastic "edge trim" from McMaster.com or other sources would bend into nice coil forms as well. Should be able to find "edge trim" at the local hardware store as well. If it doesn't bend tightly enough, heat the plastic till it softens and bends easily.

Marty

Phil Pilgrim (PhiPi)

A simple plastic kite-line spool comes to mind ...



-Phil

Mark_T

If you have access to a laser cutter many forms can be done - although things like this leave
loads of scrap circles (useful for other projects of course). The technique is to build up a
structure in layers of acrylic which you can then glue together.

garyg

Hi
This sounds like 3D printing could work out for you.
When I'm building things that need a particular shape I usually draw up what I want
using Sketchup, and send the design to someone
that has a 3D printer.
I use MakeXYZ.com
I found a pretty good guy that lives within 1/4 mile of where I do.
I found this to be a pretty good option lately.

gg

RickB

Look for "crystal radio" "coil form" or "coil former"

Here is a styrene coupling example.
http://makearadio.com/coils/cylindercoils.php

The pdf catalog.
http://genovaproducts.com/docs/PlumbingCatalog.pdf#page=9
Not exactly what you want, but close.

Sections of large diameter cardboard mailing tubes? Make flanges to fit on the outside diameter from plastic, thin plywood?

Various sizes of plastic buckets are available. The lack of a flange at the end is the part that's missing.

What is the frequency range?

Heater.

I was waiting for the 3D printing solution to show up.

So much easier than using any common or garden round thing that happens to be lying around

How on Earth did Helmoltz and co. get by without a 3D printer?

xanatos

Thanks folks, some good ideas, I'll probably wind up with the PVC plumbing pipe as a former and wind over tape, then slide the coils off.

Appreciate the ideas!

Dave

Buck Rogers

A good question.

Of course most of the readers may not know who that guy was. I believe I do, but it was a very long time ago.

RickB

xanatos:

What is the frequency range of your project?

xanatos

RickB wrote: »

xanatos:

What is the frequency range of your project?

DC to low frequency ac or pulsed dc. I'm making a few magnetic bottle configurations, just holding some plasma in place.

Heater.

xanatos,

...just holding some plasma in place.

You say that so casually. Isn't "just holding some plasma in place" still an unsolved problem in building nuclear fusion reactors that has cost us billions of dollars in research already?

I'm curious to hear what you have in mind.

xanatos

I'm probably quite mis-informed, but it's not that we can't contain it at all, it's just that it leaked, badly. The Polywell design leaked at the cusps like a sieve (at least the initial iterations). So high beta containment I believe is what they called the newer designs like Lockheed came up with.

That said, there are containment devices all over the place - have you ever seen those little "Plasma Balls" you can buy at novelty shops? It's just not a very robust plasma I'm just playing with some gentle plasmas and watching their configurations change when I change the field geometries.

I even saw a video the other day of someone making a plasma "thingy" with a wine bottle (and a good vacuum pump & HV source)! I'll try to find the link http://www.quantumdiaries.org/2015/02/04/physics-wine-plasma-fun-2/ Please note step 1: Drink a bottle of wine. The instabilities and resonant nodes are visible in the lines in the plasma as it propagated in the bottle. And he was just playing with the plasma with a solid magnet.

I'm trying to make specific and stable shapes. And I can do this for cheap while I build up the funds for my next advance on my other more involved project

Heater.

xanatos,

Ah, OK, cool. I'm all up for such experiments and demonstrations.

Be careful with that mixture of wine and high voltage power supplies!

xanatos

The wine & HV part I'm an old hand at I'm just trying to show that I can indeed shape a plasma to look like a unicorn