I bought a new silicon bed heater and aluminum bed does not appear to be getting accurate temperature readings. The product docs clearly states that the thermistor is a "NTC 3950 Thermistor built in the heated bed” with Marlin setting #11 as the setting of choice. But, I am having problems getting correct temperature readings from the bed heater thermistor. The temperature readings all seem to be about 16c degrees HIGH. When the heater is OFF, it would read 41.75c. But when I compare that to my IR Temperature gun, it would read 26.1c.
This is also true when turning on the heater and heating the bed to 55c. The temps goes up as expected to the thermistor reading of 55, but again, when I measure the temp on top of the bed with the IR temp gun, it measures ~39c. After that is steadily maintains what it thinks is 55c.
Just to be sure, I tried the other 3950 Marlin settings (#1, #8, #13 and #75) and all seem to have about the same kind of issue: Thermistor reports about 15-16degrees higher than my IR gun.
To verify that the IR gun is working correctly, I checked it with the hot end temps. The hot end thermistor reads the ambient temp (hot end OFF) as 25.5c. The IR gun, pointed at the hot end tip, reads it a 26.3. Different, but close enough to tell me that the gun is appears to be working correctly.
I would assume that there would be some difference between the place that the bed heater thermistor is and where I did the IR gun readings (center bed, on top). But a nearly 16 degree difference? That seems a little high.
Is there some setting that I can do in Marlin to correct this difference?
Is there another thermistor setting I can try besides the ones above (#1, #8, #11, #13 and #75) ?
Any other suggestions or ideas?
gene
Silicon bed heater (http://a.co/fVSjvr3)
Aluminum bed (https://www.amazon.com/dp/B019BGAB7K)
IR Temperature Gun (http://a.co/4OGZtMX)
Azteeg X3
Octoprint
Marlin 1.1
This is also true when turning on the heater and heating the bed to 55c. The temps goes up as expected to the thermistor reading of 55, but again, when I measure the temp on top of the bed with the IR temp gun, it measures ~39c. After that is steadily maintains what it thinks is 55c.
Just to be sure, I tried the other 3950 Marlin settings (#1, #8, #13 and #75) and all seem to have about the same kind of issue: Thermistor reports about 15-16degrees higher than my IR gun.
To verify that the IR gun is working correctly, I checked it with the hot end temps. The hot end thermistor reads the ambient temp (hot end OFF) as 25.5c. The IR gun, pointed at the hot end tip, reads it a 26.3. Different, but close enough to tell me that the gun is appears to be working correctly.
I would assume that there would be some difference between the place that the bed heater thermistor is and where I did the IR gun readings (center bed, on top). But a nearly 16 degree difference? That seems a little high.
Is there some setting that I can do in Marlin to correct this difference?
Is there another thermistor setting I can try besides the ones above (#1, #8, #11, #13 and #75) ?
Any other suggestions or ideas?
gene
Silicon bed heater (http://a.co/fVSjvr3)
Aluminum bed (https://www.amazon.com/dp/B019BGAB7K)
IR Temperature Gun (http://a.co/4OGZtMX)
Azteeg X3
Octoprint
Marlin 1.1
- PIDTEMPBED is NOT enabled.