That would be my concern, too. If the extra heating power is used to overcome an insulation of the sensor, then the nozzle would effectively run hotter.
That would be my concern, too. If the extra heating power is used to overcome an insulation of the sensor, then the nozzle would effectively run hotter.
I don't think so - it's a closed-loop servo system, controlled by the microcontroller based on the thermocouple signal. When it gets to the desired temp, the controller will throttle the power input down to maintain it correctly.
I don't think so - it's a closed-loop servo system, controlled by the microcontroller based on the thermocouple signal. When it gets to the desired temp, the controller will throttle the power input down to maintain it correctly.
Yeah…but what if the sensor reads lower than the actual temp? Let’s think about an extreme case…Lets assume we have a 1mm airgap around the sensor …target temp is 250C…the heating element would have to heat the block to, I don’t know, maybe 400C until the sensor reads 250. So the block would effectively be 400C but the closed loop sytem thinks it runs at 250… Am I missing something?
I know…there’s probably a limit for the heater amps in the firmware…
But this scenario was extreme on purpose just to explain the logic. So what if the heat transfer behavior of the V2 block is such that the sensor reads 5C or 10C lower? Then the nozzle would run 255 or 260… The electronic thinks it’s 250…no errors, just harder to remove supports.
We all can agree that the V2 block has some kind of different heat transfer behavior…otherwise this thread wouldn’t exist and there wouldn’t have been recommendations to clean out/roughen up the holes in some cases…?
According to Zortrax, the problem was due to the increased thermal mass of the larger block requiring more heat input to offset convection and radiation losses into the ambient environment. It was solved by increasing the amount of heat input available to balance the losses. No mention was made of thermal conductivity issues.
This issue does not apply to the sensor - it is not an energy source, and it doesn't care about how hard the heater has to work to compensate for losses. It simply sits there and measures the temperature in the middle of the block. Even mild amount of insulation around the sensor wouldn't affect the sensor's operation, because there is negligible heat flow to or from it. Thermal circuits are analogous to electrical ones: if a lot of current (heat) is flowing, then a small resistance (insulation) can cause a significant voltage (temperature) drop between one side and the other. In the case of the heater, lots of heat is flowing, so you don't want any insulation. But the thermocouple is like a "high-impedance" node in an electrical circuit - little heat is flowing into or out of it, so even if there's insulation there won't be a significant temperature gradient across it.