Thermocouple question

Chris Lyons

Chris Lyons

Joined
Feb 22, 2017
Messages
89
Hey guys,

So.. I used a custom search and really did not find an answer to this.

What I am trying to find out without having to rip up my forge or drill holes to test it is this:

If I insert my TC into the kaowool from the front (or back) of the forge, into about the middle...will I get a somewhat accurate reading of the temperature inside the forge?

My theory is that once the forge is hot throughout, if the flame remains unchanged then I will get a reading of the overall chamber temp. Of course it will be slightly hotter directly under the burner flame, but maybe the difference is not great enough to matter?

random though I had this afternoon and not sure if anyone has done this successfully.

note: my main function for this type of application would be for forge welding.

Thanks
 
The kaowool is an insulator. It would be OK to place the TC in the satanite coating over the wool. You could set the TC in the forge on top of the wool right down the centerline. Have the tip at the middle of the forge. Put the satanite over the TC as you line the forge. The TC will read the chamber wall temperature. After the forge runs for about 10-15 minutes the wall should be about the same as the chamber. Thie would be good for HT, as the blade will be sitting right over the TC.

For me, your idea is not worth the trouble. Also changing a TC would require tearing up the forge floor.

My TC that runs the PID is sitting in a 3/4" ceramic sheath on the side of the chamber floor, where the wall meets the floor.

Use a heavy size TC ... 1/8" or 8-10 gauge. The stainless clad TC work OK, but often are lighter gauge leads. If placing a TC in a forge, a ceramic sheath is very advisable.
 
Thanks Stacy,
I have this one in the 12" with ceramic sheath. http://www.auberins.com/index.php?main_page=product_info&cPath=20_3&products_id=39
I am using a forge I made from a freon tank with 2" kaowool, firebrick on the floor, all covered with a satanite and ITC coating.

The reason I wanted to "bury" it was to protect it. I initially had it coming in from the back and sort of suspended under the burner port so that it was out of the direct flame (flame hits the opposite wall), but the ceramic broke in several places and I'm not entirely sure why.... I sent photos to auberins and they said it shouldn't have broke and replaced it for the cost of shipping, which was cool.
So I was thinking of a better way to install it.

Sounds like I should just lay it down in the corner where the firebrick floor meets the wall, maybe encapsulate it into the corner with satanite.
 
Yes, use some stanite to bed it and make the transition smooth. The satanite will heat up as the chamber soaks and give a good reading. The only caveat when using a sheath and potting it into the corner/side is that any changes in temperature will be slower to show up, so allow things to stabilize after adjustments before considering the reading to be accurate.
 
I give some simple instructions to people that buy thermocouples from me. I know some people rely on their thermocouple, particularly in outdoor forges with variable lighting. However, a thermocouple seems to make the most sense as a learning tool.

To use the thermocouple, I recommend placing the probe under the metal
as it sits in the forge. This will give the most accurate reading.
Typical use is to learn the correlation between temp and color. After
a while, you will no longer need the thermocouple except for HT.
 
Atlas Knife Company said:
I give some simple instructions to people that buy thermocouples from me. I know some people rely on their thermocouple, particularly in outdoor forges with variable lighting. However, a thermocouple seems to make the most sense as a learning tool.

To use the thermocouple, I recommend placing the probe under the metal
as it sits in the forge. This will give the most accurate reading.
Typical use is to learn the correlation between temp and color. After
a while, you will no longer need the thermocouple except for HT.
Click to expand...

Well the lighting in my workshop does vary as I have a lot of natural light during the day, and at night just one flourescent shop light.. so verifying (even the approximate) the internal temp of my forge is helpful to me.

By under the metal, you mean the work piece (blade)?
It was my understanding that a TC probe placed naked in the forge would seriously degrade the lifespan of the TC. Unless you are suggesting that the metal is going to protect it?
I thought that was the whole purpose of the ceramic sheath.
From what I have read here and elsewhere, I wouldn't say that the typical or primary use of the thermocouple is to learn the correlation between color and temperature.

While I am appreciative of your suggestion, unless you can explain to me why this is a better option than the solution discussed above (color aside, as I imagine that benefit would still be present regardless), I am not likely to reconsider the method of installation based on this.
 
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