For a HT oven, either in the top center, or in the back about 2" below the top.
For a TC in a small forge, I drill the hole (about 3/4") for a 8" to 10" long TC sheath from the back at the two o'clock position. It is located so the sheath will sit just off, and parallel to the upper chamber wall. Start with a 1/4" hole and then enlarge it. Once everything is located properly, I use satanite to cement the sheath in place.
The TC is slid in the sheath unil the tip is in the end. Pieces of kaowool are slid down the sheath to pack the last 3" ... but don't shove them more than half way down. You want open space around the last 2"-3" near the tip. Slide the TC block right up to the end of the sheath tube. Make sure the TC wires are kept away from the rear port heat blast and off any hot metal.
A TC in the chamber will help you control the temp up to 2000F, but may read off if the flame is on it. A chamber mounted TC works best on a medium to larger forge that will be fully soaked and the flame controlled by a PID.
When using a muffel pipe for HT, I slide the TC in the pipe next to the blade. I have plugs on my TCs, so I just unplug the one from the sheath and plug in another one which I slide in the muffel. When setting up a PID or a pyrometer readout device, you should always have it connected to a Type K socket. That allows plugging any type K TC into it.
BTW, just sticking a TC in the open forge without a sheath will not work. The TC will last a few hours of run time and then be burned up. It needs to have the sheath to protect it from the hot flames and gasses. The sheath gets heated to the chamber temp and the TC reads that temp. It is slower to react to fluctuations in the flame, which is good, and the reading is more like what an object in the forge will be.
