How are you winding flat coils for emp launchers / Electromagnetic Projectile Accelerators / Forums

Forums

4hv.org :: Forums :: Electromagnetic Projectile Accelerators

« Previous topic | Next topic »

How are you winding flat coils for emp launchers

1 2 next

Move Thread

LAN_403

w1vlf

Thu Apr 24 2008, 03:07AM

Registered Member #1329 Joined: Mon Feb 18 2008, 07:31PM
Location: Harwinton Connecticut
Posts: 53

Hello Folks

I would really like to hear from folks about winding flat coils.
What kind of jigs are you using? I want to be able to stack several coils and glue then solidly together.

After reading Tristan's post, I too would like to experiment with different diameter projectiles.
I recently acquired some, 7/8", 1", 1-1/2" and 2" aluminum stock to cut projectiles from.

Also my power supply, 6000 uF @900 volts has been proving stable and reliable

Winding good flat coils is my new stumbling block.
I have literally spent 100 hours trying to effectively and relibably wind the coils.
The wire sizes to be used range from #14, #12, #10

Any one have any tips they would care to share ..Please...?

PauLC
W1VLF

...

Thu Apr 24 2008, 06:46AM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

The method I have heard (although, have not confirmed) to work well is to take a piece of wood with a 1/4" hole on the middle, then poke the wire through it, and jam a 1/4-20 bolt through the hole. Then sandwich another similar plate on top, so that you have wood-wire-wood, and tighten the bolt. From there simply wrap as many turns as necessary... The tricky part is getting the wire to stay in one place when you take the top plate off which I believe is best solved by having some glue on the wire as you wind it, and putting waxed paper on the wood to keep the coil from sticking.

Cheers

Electroholic

Thu Apr 24 2008, 11:18AM

Registered Member #191 Joined: Fri Feb 17 2006, 02:01AM
Location: Esbjerg Denmark
Posts: 720

Barry

Thu Apr 24 2008, 02:07PM

Registered Member #90 Joined: Thu Feb 09 2006, 02:44PM
Location: Seattle, Washington
Posts: 301

Working with very heavy copper is bordering on metallurgy. Be thinking about techniques like heat treating to help the copper relax into its new shape. I've seen annealing used successfully on a large flat spiral coil made of rectangular cross-section copper.

Good luck, Barry

w1vlf

Thu Apr 24 2008, 03:55PM

Registered Member #1329 Joined: Mon Feb 18 2008, 07:31PM
Location: Harwinton Connecticut
Posts: 53

Barry, I agree working with #12 and #10 is where the real problems start. #14 and smaller is relatively easy to work with. Coincidently I have a metallurgist friend who I plan to quiz on this topic.

Electroholic, thank you for the link. I have watched that video now a number of times. But Fast makes it seem easy. Today I will be getting a a jig made for with several spacers for the different wires I have and will be wind coils with. SOmehow they must build these coil commercially and I wonder how they do it??

A little while back I saw a beautiful coil that was recessed itoa pice of machined delrin. It was so perfect. I wonder how that was wound. It was perfect!

PauLC
W1VLF

Electroholic

Fri Apr 25 2008, 06:35AM

Registered Member #191 Joined: Fri Feb 17 2006, 02:01AM
Location: Esbjerg Denmark
Posts: 720

I totally agree with you, thicker wires like 10awg are much harder to work with. I haven't done much with pancake coils myself, but i found that if i first try to get the copper to bend to the correct curvature and not worry about the "flatness" of the coil.
First I wind the wire on a dowel, then i expend the turns from one end, make a conical spring/pyramid kinda coil, then try to make it flat. You can get a much denser coil this way.
Because the copper deforms elastically for a little bit instead of just plastically, it springs back a bit. and with the sandwich style jig, its impossible to overdeform the copper to compensate this.
BTW my coil was 12awg and only 15t. and has a 2cm hole in the middle.

FastMHz

Wed Apr 30 2008, 05:52PM

Registered Member #179 Joined: Thu Feb 16 2006, 02:08AM
Location: Hagerstown, Maryland - Close to Prime Outlets
Posts: 287

My friend and I are now winding coils with flat wire - it makes it soooo much easier. There are spools of wire on ebay that are 1/4" wide and the thickness of 12awg. Unlike round wire, it doesn't try to overlap nearly as much as you wind. I 'd still use the same bolt and wood plate technique. He's posted some pics on his site:

Flat Wire Coils

Quantum Singularity

Thu May 08 2008, 11:47PM

Registered Member #158 Joined: Sun Feb 12 2006, 09:53PM
Location: Central Ohio
Posts: 282

Good find FastMHz! I scored some flat wire about a year ago and was hoping it would boost efficiency pretty good, was going to be my little secret I'd unveil. About a year ago I searched the net endlessly trying to find it for sale, the only thing I could find would have been a 10 pound minimum and over $100 so I thought I was pretty lucky finding 2 pounds. Thought when I finally built a coil I'd be the first one sporting flat wire, you beat me to the punch again, lol! I actually just recently got my first coil wound with flat wire, done some low power testing in the garage but also having problems with my chrono so dont have results yet. And looks like we're going to be moving soon, so could be a few months before I'm able to do much with it. But so far it looks promising.

w1vlf

Fri May 09 2008, 02:10PM

Registered Member #1329 Joined: Mon Feb 18 2008, 07:31PM
Location: Harwinton Connecticut
Posts: 53

FastMhz, Tristan, Is this wire you are talking about the stuff for $32.00 for 75 feet on ebay? ALso how many feet did it takr to make the coil you and you friend are making?
One more thing, do you think that the thickness of the insulation on this wire will be an impediment to maximizing flux in a given area circle?
Thank you
PauLC
W1VLF

Quantum Singularity

Sat May 10 2008, 02:57PM

Registered Member #158 Joined: Sun Feb 12 2006, 09:53PM
Location: Central Ohio
Posts: 282

Well Fast will have to respond for sure, the 75' deal was all that I saw though so I assume thats what he was talking about. The stuff that I have is magnet wire - the glossy red finish, so its no different than the regular round wire as far as insulation goes, although I do believe it is the heavier high temp insulation.

Flat

1 2 next

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob