Anyone want to exercise their algebra muscles?

[weo]

Hello all. I've got what should be a "simple" algebra problem, but my aged muscles are to atrophied I guess.
I bought a new TC to check the drift on my year-plus old TC. They were positioned one on top of the other in my forge. With the old one on the top, it read ~60F degrees higher and with the old one on the bottom, it read ~120F lower. So, how far off is my old TC?
Thanks.

 

[Sean Yaw]

I could be way off on this. As a friend says: "Trust this consultation only as much as you paid for it".

Would it not matter what the actual temperature difference between those spots is? If (1) they are the same temp and (2) you trust the new TC, then the old one had a 180F swing (+60/-120). If (1) those spots actually have a temperature difference of D (e.g. D = 10F), (2) the top is warmer, and (3) you trust the new TC, then your old TC had a 180 - 2*D degree swing (+60 - 10 = +50 / -120 +10 = 110, when D = 10). If you can't accurately estimate the actual temperature difference between those two spots, or you do not trust your new TC, I'm not sure you can say a whole lot.

 

[Stacy E. Apelt - Bladesmith]

When you say "on top of each other" are you saying they were touching?
Can you show us how they are in the oven and where/how the TC leads are attached to the TC wires?
How are you reading both? Hooking one up and then hooking the other? Or do you have two readout devices?
Are you sure you didn't reverse a lead when changing from one position to the other?

Set them side by side about an inch apart and tell us what the read. Do it at 500F, 1000F, and 1500F.

 

[weo]

Sorry, here's a better picture (hopefully anyway). Each TC was in a ceramic sheath.

How are you reading both? Hooking one up and then hooking the other? Or do you have two readout devices?

2 readout devices with identical wiring, plugs and TCs. So on day one, the old TC was in TC1 and read ~60F lower than the new one in TC2. The next day all I did was swap the TCs from one sheath to the other, so the old TC was in TC2 and the new one was in TC1 and it read ~120F higher.
So day 1: TC1 = 2000 and TC2 = 2060
on day 2: TC1 = 2000 and TC2 = 1880