If you need assistance, please send an email to forum at 4hv dot org. To ensure your email is not marked as spam, please include the phrase "4hv help" in the subject line. You can also find assistance via IRC, at irc.shadowworld.net, room #hvcomm.
Support 4hv.org!
Donate:
4hv.org is hosted on a dedicated server. Unfortunately, this server costs and we rely on the help of site members to keep 4hv.org running. Please consider donating. We will place your name on the thanks list and you'll be helping to keep 4hv.org alive and free for everyone. Members whose names appear in red bold have donated recently. Green bold denotes those who have recently donated to keep the server carbon neutral.
Special Thanks To:
Aaron Holmes
Aaron Wheeler
Adam Horden
Alan Scrimgeour
Andre
Andrew Haynes
Anonymous000
asabase
Austin Weil
barney
Barry
Bert Hickman
Bill Kukowski
Blitzorn
Brandon Paradelas
Bruce Bowling
BubeeMike
Byong Park
Cesiumsponge
Chris F.
Chris Hooper
Corey Worthington
Derek Woodroffe
Dalus
Dan Strother
Daniel Davis
Daniel Uhrenholt
datasheetarchive
Dave Billington
Dave Marshall
David F.
Dennis Rogers
drelectrix
Dr. John Gudenas
Dr. Spark
E.TexasTesla
eastvoltresearch
Eirik Taylor
Erik Dyakov
Erlend^SE
Finn Hammer
Firebug24k
GalliumMan
Gary Peterson
George Slade
GhostNull
Gordon Mcknight
Graham Armitage
Grant
GreySoul
Henry H
IamSmooth
In memory of Leo Powning
Jacob Cash
James Howells
James Pawson
Jeff Greenfield
Jeff Thomas
Jesse Frost
Jim Mitchell
jlr134
Joe Mastroianni
John Forcina
John Oberg
John Willcutt
Jon Newcomb
klugesmith
Leslie Wright
Lutz Hoffman
Mads Barnkob
Martin King
Mats Karlsson
Matt Gibson
Matthew Guidry
mbd
Michael D'Angelo
Mikkel
mileswaldron
mister_rf
Neil Foster
Nick de Smith
Nick Soroka
nicklenorp
Nik
Norman Stanley
Patrick Coleman
Paul Brodie
Paul Jordan
Paul Montgomery
Ped
Peter Krogen
Peter Terren
PhilGood
Richard Feldman
Robert Bush
Royce Bailey
Scott Fusare
Scott Newman
smiffy
Stella
Steven Busic
Steve Conner
Steve Jones
Steve Ward
Sulaiman
Thomas Coyle
Thomas A. Wallace
Thomas W
Timo
Torch
Ulf Jonsson
vasil
Vaxian
vladi mazzilli
wastehl
Weston
William Kim
William N.
William Stehl
Wesley Venis
The aforementioned have contributed financially to the continuing triumph of 4hv.org. They are deserving of my most heartfelt thanks.
I was thinking of using brake line tubing for a small 3 stage coilgun project. Im using this cause its the only thing around where i live that would be practical, what i wanna know is is if this is acceptable for building a decent coilgun? as the tube is ferromagnetic
Registered Member #2973
Joined: Tue Jul 06 2010, 01:13PM
Location: Leeds UK
Posts: 9
Any type of conductive barrel material is not ideal as you will get eddy current loss. This, however, could be reduced by "slotting" the barrel.
With any type of ferro-maagnetic barrel material you will get additional losses such as hysteresis loss.
I think (though i'm not sure) a ferro-magnetic barrel might produce another problem: The barrel would experience a force on it in the same way that the projectile does. When energised, the coil will exert a force on the barrel which will try to pull it to the position of least reluctance. So, if you start with more barrel material sticking out of one end of the coil, when you energise, a force will act on the barrel to pull it in such a direction that, if the barrel were unrestrained, it would end up with equal lengths of material sticking out of both ends of the coil.
So, overall, IMHO a ferromagnetic barrel is not a good idea.
Registered Member #2648
Joined: Sun Jan 24 2010, 12:45PM
Location: Australia
Posts: 291
The best barrel material would be:
Non-Conductive (no eddy currents)
Thin
Non-magnetic
Straight
Rigid
Low Fiction
@ElectronicsBob: Yes any conductive barrel material is bad for efficiency and slotting would help but I recommend not using a conductive barrel at all. But the barrel would not be pulled by the pulse because the barrel would: A. be fixed B. be already mostly inside the coil C. much longer than the coil.
What would likely happen and cause problems is the barrel conducting magnetic flux away from the projectile.
Here is a good idea from FESys (future experimental systems), Robert Wilsford:
Click to enlarge
here the barrel does not go inside the coil, the coil comes in direct contact with the projectile and the barrel serves it's sole purpose to direct the projectile. When setup like this it has the advantage of much greater barrel choice, there is no limit or negative effect of barrel thickness, there is also less eddy currents if material is conductive.
Registered Member #2998
Joined: Tue Jul 13 2010, 08:34PM
Location: Swedish forests.
Posts: 26
Air is your enemy... I remember that mantra as well. Flux leakage would indeed be a big problem if you used magnetic materials. The field-lines would pass through the iron barrel instead of the projectile.
IIRC anothercoilgunsite.com didn't use a barrel at all; They glued a rigid coil directly moulded onto the projectile. Just like the picture you showed.
most of my problems are now fixed, i managed to find brass tubing at the hardware store...lol....walked right past it like 3 times before i noticed it XD
Registered Member #1451
Joined: Wed Apr 23 2008, 03:48AM
Location: Boulder, Co
Posts: 661
brass works really well if you slot it with a dremel. It has really low friction with steel and is very rigid. I've used it a few times and is great. I bet it's the same stuff you found as I got it at the hardware store too
This site is powered by e107, which is released under the GNU GPL License. All work on this site, except where otherwise noted, is licensed under a Creative Commons Attribution-ShareAlike 2.5 License. By submitting any information to this site, you agree that anything submitted will be so licensed. Please read our Disclaimer and Policies page for information on your rights and responsibilities regarding this site.
Barrel Material
