I have always suspected the chamber thermistor was on the slow side to react. And it’s certainly in a very questionable place.
But today, after running a bed temp check, and running the chamber temp up to 41C, I removed the top and door, and the sensor is still reading 39C after a half-hour. Frankly, there’s no possible way the temperature in that chamber is still that high. (Room temp is 21C) Which leads me to believe that it’s not really measuring the air temp, it’s measuring the back wall temp. My Thermapen says air temp near the back wall is 26C
Anyone have ideas on relocating/replacing the chamber sensor? I’m thinking something just above or below the Y-rails on the left side, out from the wall a bit?
Measuring air temperature is a difficult task. Doing it inside a box with a divided box with still air is exceptionally difficult. An immersion sensor can only measure the temperature of the air it actually contacts. The air temperature 100mm away may be vastly different.
You can move it anywhere you want. You can also change to a different thermistor type by changing 1 line in printer.cfg. Smaller sensors have faster settling times but are prone to wild stings in reported temperature.
[temperature_fan exhaust_fan]
pin: PB0
sensor_type: EPCOS 100K B57560G104F
sensor_pin: PC4
max_power: 0.8
shutdown_speed: 0
kick_start_time: 0.5
cycle_time: 0.01
off_below: 0.1
min_temp: 0
max_temp: 70
target_temp: 30
max_delta: 1.0
control: watermark
gcode_id: D
tachometer_pin: PB1
tachometer_ppr: 1
tachometer_poll_interval: 0.0046
`
You can also define custom calibrations for any resistive sensor.
BUT there is no single location that would always have excellent correlation with the temperature of the air that surrounds your print. You need to find a way to continuously "stir" the air in the chamber. Mounting a 50x15 turbo fan to flow across the existing sensor may be all you need.