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Describe your issue:
Hello,
I’ve moved my diy 3d printer from Mega + RAMPS to MKS Robin Nano 3.1
Both are using Klipper - modified all values in printer.cfg and everything is working OK except hotend sensor.
At room temperature values are looking good - comparing bed temperature and hotend temperature (difference is like 0.3 degrees), but when i set temperature to 50 degrees and measure it with external thermometer, hotend barely hit 35 degrees.
On Octoprint printer reports that temperature is 50.
Initially decided that sensor was broken during hardware replacement, so i bought a new one, unfortunately result with new sensor is absolutely same.
At higher temperatures difference is bigger - 200 degrees with actual temperature 130.
Moved sensor from TH0 to TH1 (changed pin in configuration ), but still same.
Tested millions of combinations of sensor_type and pullup_resistor, but without success.
Yes, hotend is hot and stay hot (didn’t mixed hotend and bed termistors pins)
Regarding your second question probably playing with pullup_resistor i’ll mange to get 50 degrees when i set it to 50, but at room temperature will be 9-10 degrees, when bed showing 23. not sure what will happen at 200.
Regarding 8500 - just a test value, before i write here. In theory should be 4700.
This is old config from RAMPS (was working for 2 years):
Here I meant the sensor type. I assume the type is not correct. If the shown temperature differs from the measured temperature, that can be a hint for that issue.
How did you measure the temperatures?
BTW: When posting code, please use the Preformatted text feature of the forum editor.
Yes, as i know this calibration is for smooth handling of temperature. In my case sensor “thinks” that temperature was reached, when actually temp is much lower.
sensor_type:
# Type of sensor - common thermistors are "EPCOS 100K B57560G104F",
# "ATC Semitec 104GT-2", "ATC Semitec 104NT-4-R025H42G", "Generic
# 3950","Honeywell 100K 135-104LAG-J01", "NTC 100K MGB18-104F39050L32",
# "SliceEngineering 450", and "TDK NTCG104LH104JT1". See the
# "Temperature sensors" section for other sensors. This parameter
# must be provided.
There is no schematic for the V3.1 but I bet this is accurate.
I’m 99% positive the pull up is 4.7k for all 3.
You can verify. Measure the volts pin to pin (sensor unplugged). should be 3.3v. Switch to mA and measure the short circuit current. Should be 0.702 mA.
Hi, thanks for your time - already tested to swap TH0 and TH1 - result was same
Today I’ve swapped TH0 and TB - on 50 degrees set on Octoprint, actual temp on hotend is 36.7
As i know RAMPs is 5 V and MKS Robin Nano is 3.3 V. Not sure if this is somehow related .. just hope to find something, otherwise should send this board to trash.
Measure the voltage at the mainboard connector with sensor unplugged.
Measure the resistance of the thermistor at room temperature (20 °C)
Measure the voltage at the connector with it plugged in.
Another test is to plug your bed thermistor into each of the 3 sockets. Update the pin in your configuration and test to see if the bed heats normally. That would (more or less) eliminate the board being the problem.
This type of external thermometer - probably not most accurate, but at 200 degrees difference that i have is ~70 degrees, so this one is good enough i think.
Also fillament is stuck in hotend at 210 degrees, also at 50 degrees i can touch hotend with bare hand.
Now i’m mesuring at 50 degrees, just because it’s faster to “reach” this temperature and check with external thermometer.
Sorry for budding in, but I’m not sure the right questions are being asked.
I have a fair amount of experience with the MKS Robin Nano V3.1 and I haven’t seen anything like what you are reporting.
FYI. The MKS Robin Nano V3.1 has 4.7k pull up resistors for the thermistor inputs.
First off, what are the thermistors that you are using? Where did you get them?
Secondly, you’re going to need to explain how you are measuring the temperatures in more detail:
Why would you think this is good enough? Is this a meat thermometer? Could you post more information about it?
Personally, when I’m checking hot end temperatures, I use a TPI 367D with a point thermistor probe:
As for the bed temperature, I use an imaging camera like:
I use this because it will highlight cool spots if there is a break in the bed heating element wires. You can also use a $20 infrared non-contact temperature sensor for this that you should be able to buy at a local hardware store.
I’m asking if the unit you’re showing is a meat thermometer because they are not appropriate for this type of application. They are designed for reading the temperature of the surrounding volume, not a point (like a hot end’s nozzle) or an area (like a heated bed).
Finally, can you describe as precisely as possible what you are setting the hot end and heated bed to and what you are measuring? What you’ve written previously is difficult to understand exactly what’s happening.
I had the same problem with my MKS Robin-Nano and a “100k Hisens 3950” thermistor,
then I started measuring the actual resistance of the thermistor at different temperatures, which you can specify separately in Klipper. After that, everything was perfect.
I measured with a thin thermal coupling inside the nozzle, it does require some fiddling.
I had to heat with a separate 24V power supply for the heater because the mainboard does not work without the thermistor.
