How to make this digital thermometer work?

weo

weo

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Sep 21, 2014
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Hello all. I've had this thermometer in my shop for the past few years that we used in a custom built forge my friend made to make sure we maintained forge welding temps while making an 80# medieval style wrought iron anvil with tool steel face that we made for a local renaissance village (here's a video of the last day we put the tool steel face on:
). I think it had a ceramic tube over the probe when we used it. I'd like to use it to monitor my forge temps when heat treating my knives.

LSrUAv2.jpg

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That's kaowool around the probe
Do I need to do anything to the probe or rest of it to make it work and not ruin it? I'm thinking that I need a ceramic insulating tube around the end of the probe (if so where should I get one), but maybe not seeing as how I'm not planning on getting it up to forger welding temps.

Thank you

as always
peace and love
billyO
 
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Do I need the ceramic tube? I put up a couple 1" firebricks in front of my ribbon burner and my blades in a piece of schedule 20 pipe that I flattened and would be putting the thermometer in that as well.
 
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if it's in the muffle you shouldn't need the ceramic sheath but if it's in the forge atmosphere it does need one.
 
John, does the muffle have to be enclosed? (Or should I not have had to ask that because if it is closed how do you get the blade out to quench?o_O)

On an unrelated note, should I send you some blocks or wait a bit longer?
 
If the muffle is sticking out of your forge openings I wouldn't think it would need either end enclosed. If it's sitting inside your forge, and forge atmosphere is running through it, then you'll probably want the ceramic sheath.

I think May for the blocks is our best bet. I need 60s and it's still freezing overnight here.
 
Thanks, John. Let me know when you're ready if I forget to pester you.

Out of curiosity, why does the atmosphere affect the probe more than the temperature?
 
The gases are corrosive in nature. The probe is inconel or some other temp resistant alloy, but the hot gas flow will kill it. In s muffle, just high temp but still atmosphere they're fine.
 
For HT at Carbon steel temperatures, it should be ok without a sheath. Actually, both Oxidizing and Reducing atmospheres will kill the thermocouple at high temperatures. HT temperatures are low enough that it'll take a long time. The legs are Chromel and Alumel if it's a type K.

If it spent much time at forge-welding temperatures, the thermocouple may have suffered some "drift". It's unlikely to be enough to cause an issue at Carbon steel HT temperatures if you aim for the middle of the temperature range for your steel, where you have a few degrees of wriggle room either way.

You might want to check that there's a gap between the legs all the way to the tip while in use and that there's no shorting to the muffle, etc.
 
Thanks all. One final question. I'm in year 12 of a 2 year remodel of a 75 y/o home, and when I replaced the wiring, I saved all the insulators that are 3 1/" ceramic tubes and 4 of them would cover the probe (with about 2" to spare). The end would be open, however.
Would these be adequate, or do I need a single tube without seams and does the tube need to be capped at the end? (OK, 2 final questions:rolleyes:).

Thanks
~billyO
 
I don't know.

But if you fry the probe a new one is like $20.
 
Just went to the www.auberins.com site and see that their thermocouples and pictures of the sheaths have the tip of the probe sticking out the end.
 
Hello all. I just ordered a probe from auberins and was told that I should order their non-ceramic probe for heat-treating temps and don't need a ceramic tube in the gas forge atmosphere. They said the ceramic option is for higher temps, not due to the atmosphere.
I decided to go with the non-ceramic due to the fragility of ceramic.
What do y'all think?
 
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