I don’t know how one would calibrate a thermocouple, but we use a welding device cobbled together from carbon rod (from a dry-cell) and a 40Vdc power supply and an alligator clip. It takes 10 minutes to setup and couple of per thermocouple to weld and inspect to ensure there is a little ball of metal at the end of the two wires and there are no twists. We might do 30 or 40 in one sitting and the DIY allows us to make each to a reasonable length. (at least 2 metres). Eye protection recommended.
To attach, we use plain old super glue and tape the wires in a couple of places for strain-relief. It’s a method that has proven successful for us for many years and the TC can most often be removed without damaging the weld. What I’m not crazy about is placing a piece of Mylar tape between a bare live part and the TC to electrically isolate one from the other. Not sure what thermal conductively the piece of tape provides and what error it might introduce. Silpad or similar material is likely a better choice for that function. Ralph McDiarmid, AScT Compliance Engineering Group Xantrex Technology Inc. From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Barker, Neil Sent: Tuesday, June 16, 2009 12:37 AM To: peterh...@aol.com; emc-p...@ieee.org Subject: RE: Thermocouple welder Peter Why bother? Unless you need really long thermocouples that are not available off the shelf as pre-welded units, it simply isn't worth the time and trouble. We treat thermocouples as consumable items. They cost about £5 ($7) each and we just discard them when broken. The thermocouples come with a Certificate of Conformity, so there is no need to calibrate them. You can buy an awful lot of those with the money you would spend on a welder, and then you've got to add on the cost of the wire and the time to make the weld. With overheads, lab time costs us about £70 ($100) an hour, so £5 would buy less than 5 minutes. Do you think you can set up your welder, prepare the wires and make the weld in less than 5 minutes? Just my 2p (2c) worth. Neil Barker Manager Central Quality e2v 106 Waterhouse Lane, Chelmsford, Essex, CM1 2QU, England Tel: +44 (0)1245 453616 Mobile: +44 (0)7801 723735 Fax: +44 (0)1245 453571 www.e2v.com <http://www.e2v.com/> P Consider the environment: do you really need to print this e mail? ________________________________ From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of peterh...@aol.com Sent: 16 June 2009 00:47 To: emc-p...@ieee.org Subject: Thermocouple welder Hello friends, I am looking to purchase a very inexpensive thermocouple welder for type J and K as I have a small budget. Can anyone help please? I don't mind a used or refurbished unit. Thank you Pete ________________________________ A Good Credit Score is 700 or Above. 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