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 #2939
Joined: Fri Jun 25 2010, 04:25AM
Location:
Posts: 615
Producing a welded tip type K thermocouple is not so easy - a butane flame really doesn't get hot enough to melt the alloys. Soldering is somewhat unreliable, due to solder being so soft, and the need for an aggressive flux. Oxy-acetylene works, but a small flame is needed - we managed to make one successfully this way. Then I remembered just how hot the termination point of an arc can get (by ion bombardment), so I dug out my old NST. With the thermocouple wires twisted tightly and connected to one end of the NST it only took a couple of seconds of arc to form a nice melted ball! This was all done with fine gauge Teflon covered Type K wire. My workmate and I made 6 thermocouples in about 10 minutes this way.
Registered Member #1232
Joined: Wed Jan 16 2008, 10:53PM
Location: Doon tha Toon!
Posts: 881
Capacitance discharge welding is a long established technique for thermocouple manufacturing. The operator twists the dissimilar wires together and sets the discharge energy. When the go button is pressed there's a pop and a flash and the wires are spot welded together.
Often the same machine then invokes a TIG weld to fit the thermocouple cap to the barrel body and seal the complete assembly. Usually with a thermally conductive and humidity reducing poweder sealed inside.
I used to have a link to a video of this process, but can't seem to find it right now.
Registered Member #4081
Joined: Wed Aug 31 2011, 06:40PM
Location: UK
Posts: 139
I agree, I think it is a good solution to a challenging problem. I'm sure a lot of people on this forum are annoyed when the electrodes melt What two metals did you use?
Registered Member #2939
Joined: Fri Jun 25 2010, 04:25AM
Location:
Posts: 615
Photo of the result, next to a 1mm scale. A bit oxidised but works fine. An inert gas shield would help - but didn't have anything available.
Type K thermocouples are chromel {90% nickel and 10% chromium} and alumel {95% nickel, 2% manganese, 2% aluminium and 1% silicon}. The thermocouple wire I was using has teflon insulation, which is a PITA to strip. The other arc electrode was a 3mm dia steel rod, sharpened to a point.
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.
Making thermocouples with HV!
