Tevo Tornado Temperature overshoots

[willbill 0]

I recently replaced the heating cartridge in my Tevo Tornado with a 24V heating cartridge and now when i try heating it the temperature jumps to at least 40 degrees above what I set it. Then throughout the print the temperature will fluctuate at least ten degrees any ideas?

     I understand this is probably not the best place to ask seeing as my printer isnt made by ultimaker but ive searched for hours trying to find a solution and i cant find one anywhere.

any help is appreciated! Thank you in advance!

[geert_2 557]

Maybe the heater is too powerfull, or has a too big stored heat capacity, so it jumps over the set value? Or the sensor is too far away from the heater, so it senses the temperature changes way too late? Or the thermal connection between heater and sensor is not good enough (maybe try copper paste or the white paste like in CPU's for better contact)? Or something else along this line of thinking?

 

[willbill 0]

Im using the right voltage (24v) heater. what do you mean has a too big stored heat capacity? could the sensor be the problem seeing as ive replaces the thermistor as well? and even prior to replacing it it was jumping over the temperature.

[geert_2 557]

16 hours ago, willbill said:

... what do you mean has a too big stored heat capacity? could the sensor be the problem seeing as ive replaces the thermistor as well? and even prior to replacing it it was jumping over the temperature.

I don't know the technical name for this in English. What I mean is that at the moment at which the outside of the heater reaches its temperature, inside there could already be so much more heat accumulated, that even when switched off, this heat when traveling towards the edge makes the temperature overshoot. This is also a common problem in heating systems in homes. If the heater shuts off at the desired temp of 20°C, then there might still be so much hot water in the pipes and radiator that it overshoots. Or the thermostat might be in a location too far away from the radiator, so it doesn't sense the changes fast enough. This could also happen in 3D-printers if the heater is too powerfull, and/or the sensor too far away from the heater, or if the sensor has bad thermal contact. Further, you should also look at the Watt of the heater (not only the voltage), if that Watt is according to specs? Because that is what determines the heating. A 24V, 25W heater will generate far less heat than a 24V, 100W heater. If the system was designed for the first, then the latter will cause overshoots. I am not saying this is the cause in your system (which I don't know), but it is one of the many possibilities.

 

It could of course also be the sensor itself: wrong type of sensor, poor batch, poor thermal contact with the heater block, bad electrical contact. Or it could be the hardware- or software-settings that do the regulation: too much or not enough amplification. Like when turning a car into a corner, and correcting the turn: you could correct too much and start to zigzag, or correct not enough and go off the road. The correction has to be the exact right amount. In turning it is the driver, the "software", that is the problem, not the car.

 

But I don't know any real practical values, that is something you should ask the developers of the printer.