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.
Registered Member #8497
Joined: Tue Dec 04 2012, 06:24PM
Location:
Posts: 74
Anyone ever try and measure the contractive forces the coil experiences?
I didn't.
But I did find out that epoxy overcoats are all but useless. I normally impregnate every layer with the low-viscosity epoxy (to allow it to seep into all the crevaces), but attempted a simple overcoat on this wrapping. Epoxy used:
Registered Member #2099
Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1714
Glad to see people not afraid to do experiments and report the results.
The magnetic (Lorentz) forces on the wires of the coil itself tend to compress the coil in the axial direction and to expand the coil in the radial direction -- both motions that would increase the inductance. [edit] As would sucking in a reluctance projectile, or ejecting an induction projectile.
How did your coils hold up when you applied low-viscosity resin on every layer? Can you give us engineering data for the coil in your picture, and the circuit in which it shed its coat?
Good job, Maxwell - short coil, thick wire (I can see it wound comparably good for the diameter used). If you will be able to find "regular epoxy resin" which sets in 30min-2hr, then keep applying the mix while winding the coil to fill it all without an air gaps inside. This way it will not brake like that. As I play with just 18J per stage, I don't bother to fill all the coil with epoxy - only first half. If coil is wound tightly without loosing turns, it holds good. But I found that I can't wind a wire of 1+ mm in diameter in a perfect tight way, so I stuck with HV to minimize the current and wire diameter. The axial pulling force accelerating the projectile is dozens of kilograms (30kg at peak in my case, 18J), and squizing force is even higher. Consider those numbers as shocking reference - myself was surprized realized that.
Registered Member #509
Joined: Sat Feb 10 2007, 07:02AM
Location:
Posts: 329
Most of those clearish quick set epoxies are on the brittle side, something tougher like JB weld (maybe thinned with alcohol before application) may be in order, though I'm not positive on how well it adheres to magnet wire.
Registered Member #8497
Joined: Tue Dec 04 2012, 06:24PM
Location:
Posts: 74
Thinking of it, the epoxy does not need to adhere to anything. It simply needs to form a 'cast' to prevent the barrel from collapsing, and also prevent the wire from pulling too tight and shorting itself out.
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.
Epoxy Overcoat?
