Heat Treatment Oven (with separate control cabinet)

[hemmjo]

very impressive. I am currently working on an electric crucible furnace for casting aluminum and brass. I had intended to make the control box separate from the furnace, but for now it is mounted on the side.

I was not sure how critical the connectors are for the thermocouple. Right now I just have if connected with a terminal block. Can I just use something like a plug and jack like for a microphone?

[Dr.Al]

I was not sure how critical the connectors are for the thermocouple. Right now I just have if connected with a terminal block. Can I just use something like a plug and jack like for a microphone?

I think the connectors are quite important if you want an accurate measurement. Thermocouples work by two different metals meeting at a point (and being welded together) and generating a tiny voltage. If you connect them to some other material then you effectively introduce another thermocouple junction where the thermocouple meets the other wire and hence add another tiny voltage, giving an offset reading. There's a bit of a discussion on this starting on the last comment on this page of the thread on the woodhaven2 forum.

The green† K-type thermocouple connectors have the pins (and sockets) made of a material that doesn't introduce any offset (as long as you also have thermocouple cable the other side of the plug/socket going to the controller). The plugs and sockets aren't especially expensive - you can get some decent quality ones for a few pounds in the UK at least.

† I've said green as that's the international standard colour, but I think a different colour (yellow I think) is used in America because, well, America!

[tonyfoale]

very impressive. I am currently working on an electric crucible furnace for casting aluminum and brass. I had intended to make the control box separate from the furnace, but for now it is mounted on the side.

I was not sure how critical the connectors are for the thermocouple. Right now I just have if connected with a terminal block. Can I just use something like a plug and jack like for a microphone?

I agree with Dr.Al. You need the correct connectors for themocouples. They do not make special connectors for no good reason. Of course they'll work with other connectors but that will kill accuracy and that makes the whole point of measuring worthless.