I had 40W heater and was not happy with it so i exchanged it for 60W. After ( i think ) one month of flawless printing i started to have issues with temperature drops which range up to 20 degrees.
I am printing ABS with 295 degrees during print and without cooling.
I tried running PID calibrate for heater multiple times.
When printer is idle ( not moving ) temperature is REALLY stable with 0.1-0.2 degree deviation. When print starts , deviation can go up to 20 degrees at some point.
I am also looking for some kind of “ultimate guide for PID extruder calibration”
Problem is that if i set temperature to 295 and printer is idle temperature is pretty stable ( +/- 0.5 degrees ) , the moment printer start moving deviation starts to get higher and on certain point it fails by “extruder not heating at expected rate”
Issue is also replicable by same model where it fails basically on same place. So Your solution / advice is to just replace termistor?
Regarding termistor… Not 100% sure. I am more of design guy then printer guy ( i know i should be ashamed ) I am attaching my current configuration though.
It should be the Semitec 104NT thermistor.
I don’t really know whether it is better to use the sensor type ATC Semitec 104NT-4-R025H42G or the Generic 3950 to have more accurate readings especially at your higher temps.
However you might be at the upper limit of the V6 hotend where increased wear can occur.
Why do you print ABS with such high temperatures?
The V6 at least won’t supply the high flow rate necessary for high speeds requiring such high temps…
So for the sake of your own and your printers safety this should be clarified before swapping a faulty thermistor.
Your graph clearly showing it, your hotend (solid block of metal) can’t spontaneously lose 10 or 20 degree per few seconds, it should be slow gradual increase or decrease.
Short background:
Usually, 2 wire thermistors are usual resistors which change their resistance from temperature, your board is sending small constant current thru it and measuring a voltage drop, that voltage difference is reported to a software layer, Software from voltage drop calculates current thermistor resistance and then it’s looking at Your known pre-defined thermistor table which store relations between resistance and temperature, from that table it derive temperature on known thermistor.
Now on graph you see that when everything is static - temperature is static, when your toolhead is moving - temperature goes wild
So your issue is related to movement of Thermistor and it’s connection wires, they experience some degree of acceleration and deceleration or bending.
Issue should be inside of your thermistor or in your connection wires, Or in your electronics if your toolhead have it onboard.
As a quick test you can do following:
Heat-up your extruder to desired temperature and while toolhead is static (and temperature on graph is also static) just start knocking on it from different sides - most probably you will notice temperature changes, if your knocking is not showing issues - try to mangle with connection cables along all path to mainboard (including connector) maybe some wire is broken somewhere and have loose connection.
For me it look like another confirmation of possible thermistor or connection issues.
cube 2x2x2 is much smaller for toolhead swings, time is much smaller, heat soak is also much smaller, accelerations is almost unnoticeable, etc …
My friend is 100% sure that this is not problem with termistor but bad PID calibration.
I have tried automatically calibrate PID but results stay more or less same. I would like to explore option of calibrating PID manually.
I do not plan to connect USB to board ( with my luck it can explode or something ) looking out for some more detailed guide how to tune PID. On google I was only able to find clickbaits and useless videos how to launch auto calibration.
As @Sineos and @gaolst wrote this is a defective piece of hardware!
Why thinks your friend it is PID? If so he should be able to explain how to PID tune.
As already stated your hotend block is some inertial thermal mass that does not allow such sharp spikes unless you cool it with liquid nitrogen, but then it won’t warm up so fast…
Same with PID, it tries to shape the resulting temperature graph to more look like “you want it”.
Your heater is not so fast/powerful to heat it like that.
Just look at the rising edge of your last temperature graph and how long it takes to reach a certain temperature.
Those rising edges are with 100% power!
Heat up your hotend and slightly wiggle along the thermistor cable or check any involved daughter boards and keep an eye on the temp graph.
I did PID calibration 1.5mm from table with loaded filament and enabled fan. Results are same.
I am marking your reply as solution provided , next week i will be putting Dragon Hotend instead of 3DV6 and exchanging cables. During this process I will also verify Your theory ( not exactly sure if theory is right word for that ) about broken cables or thermistor.
I will have same hotend and heater as my friend ( exactly same provider for both ) so I will share results.
I would like to express thanks and gratitude for Your time and answers.
