Thermocouple question

[Bruce]

I bought some thermocouples that were not welded on the end. Is there
something I need to do to these wires other than just weld them together
with a torch and some flux? Is there any kind of a trick to the process?

[Ron Coleman]

Depending on what wire size you have, you can do one of several things. For small wires you can twist them together several turns, add the flux and then weld. For large wires like 8 gage, prebend the wires to their final shape and butt the ends together. Make sure you have good square contact at the ends. If your setup uses ceramic "fish spines" (short tubes) to protect the wires inside the kiln, you can use them to hold the wires together while you weld. You can also clamp them down on a workbench and let the tips hang over edge for welding.

The welds are fairly strong, but they don't like a lot of bending. You can file the weld bead to shape it if you want.

Ron

[Bert Weiss]

I bought some thermocouples that were not welded on the end. Is there
something I need to do to these wires other than just weld them together
with a torch and some flux? Is there any kind of a trick to the process?

The weld is the business end of the thermocouple, along with the exact length of the wires. I wouldn't trust my glass work to a homemade thermocouple. Why risk thousands of dollars worth of work when you can get a good professional thermocouple for $55. I just looked on the Digitry site and they sell a Type K (9" long, Inconel stainless steel sheathed, magnesium oxide packed) for $55. I have been using similar ones for 13 years now. The interesting thing is that the drift is not so much that my glass doesn't anneal just right after all these years. Your exposed home made rig won't last long.

[BobB]

I agree with Bert. You might have purchased just thermocouple wire not thermocouples. The weld opens up or breaks during a run it might be bad news.

BobB

[Tony Smith]

I agree with BobB and Bert. Go to the Omega website. For $10 you can buy an 8 gauge K-type thermocouple factory welded and tested with 12" leads... $8 for the 14 gauge thermocouple. Or you can get any insulator/length/gauge configuration you like. Omega is the largest manufacturer of thermocouples in the US (and not imported). All of their thermocouples and wire are manufactured in New Jersey to order. Their service is excellent and they are ISO 9001 certified.
http://www.omega.com/toc_asp/frameset.h ... BARE_FS_OV

Tony

[Bruce]

Ron,
Thanks for the reply. I did as you suggested and it came out really
well. I calibrated it if freezing water and boiling water and it came out
right on the money. Have not tried it in the kiln yet but will probably do
that tomorrow or the next day.

[Tony Serviente]

Bert, Tony and Bob are right-Go with Omega, spend the $ and get a stainless sheathed thermocouple. One failure of a home made weld and you have most likely more than offset the savings. I have been using the Omegas for twelve years, and have thousands of firings on them, and only three failures.