James Charles

Your project sounds really interesting—building a tube furnace is definitely doable, but there are a few things to keep in mind, especially if you go the induction heating route. A few points: Induction vs resistive heating: Nichrome or Kanthal wire is simple, but they wear out over time. Induction heating a graphite tube can be more “permanent,” but you’ll need to think about coil design, power supply, and cooling. Graphite heats via eddy currents induced in it by the coil. Thermocouple use: Induction fields can induce currents in metallic thermocouples, leading to inaccurate readings or even heating the thermocouple itself. Some tips: Use a ceramic or quartz sheath to electrically isolate the thermocouple from the graphite tube. Grounding the thermocouple casing helps, but might not fully eliminate induced currents. Non-magnetic thermocouples (like Type C or S) are less affected than ferrous ones. At high frequencies, the skin effect keeps currents near the tube surface, which may reduce interference—but exact frequency depends on tube size and conductivity. Practical setup: Many builders place the thermocouple in a small ceramic sheath inside the graphite tube to isolate it. This usually minimizes interference and allows accurate temperature measurement. In short, it can work, but careful design of thermocouple placement, shielding, and grounding is key. Experimenting with lower frequencies first can help gauge interference.