Temp fluctuation

Basic Information:

Printer Model: Creality Ender 5 plus
Stock 40w heater
Thermister (https://www.amazon.com/WINSINN-Printer-HT-NTC100K-Thermistor-Extruder/dp/B07F3SMRLJ?pd_rd_w=d53rf&content-id=amzn1.sym.deffa092-2e99-4e9f-b814-0d71c40b24af&pf_rd_p=deffa092-2e99-4e9f-b814-0d71c40b24af&pf_rd_r=V80XG5ANGBXZ5X98HZHE&pd_rd_wg=B1N5J&pd_rd_r=bf7a662f-b9d4-4cb9-81b1-14cb16af0544&pd_rd_i=B07F3SMRLJ&psc=1&ref_=pd_bap_d_rp_21_t)

Hotend (https://www.amazon.com/Haldis-Assembled-Extrusion-Extruder-Printer/dp/B09HGTT9DW/ref=sr_1_2?keywords=haldis+red+lizard+hotend&qid=1662607004&s=industrial&sprefix=haldis+red+li%2Cindustrial%2C55&sr=1-2)

Orbiter extruder v2

MCU / Printerboard: BTT SKR 3 EZ
klippy.log (7.5 MB)

In the above photo i am printing with petg at 230 degrees and with a pid auto tune at 240 with the part cooling fans full blast and the hot end cooling fan on as well. it completes the tune. but while printing it seems as the part cooling fans come on closer to full blast, i get a large dip in temp and some times get a thermal run away. i have tried some things to remidy the issue/have looser safetys. its about 75 in the room the printer is in and its pratially enclosed. i have tried new thermisters but have not changed the heater chartrig. printing at 200 does not have this issue with the same pid tune. it prints fine besides the temperature dips and the consiquens from it.

Looks like the heater is just to weak to sustain 230°C and 100% fan in the given configuration.
Stronger heating cartridge and / or a silicon sock could help.

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i have a silicon sock on always. i have a 50w heater on the side right now. i shouldnt have to change any firmware just do a pid tune after install?

what about running my hotend cooling fan at 50% speed? i have mine set to either off or 100%. is there a way to have that fan change in speed with temp deviation?

No, just PID tuning

The amount of cooling needed depends on filament and print speed / layer time and part geometry (e.g. bridging etc). The cooling capability depends on the used fan and cooling duct layout. There is no general black and white answer.
It makes no sense to make it depending on temp fluctuation nor does it make sense to either run 0% or 100%.

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when i ment hotend cooling fan i ment the heat sink fan not the part cooling fan if thats what you mean? im running a 3010 heat sink fan and 2 4010 fans with this hotend (Apogee Ender 5 Plus remix by Hobbss27 - Thingiverse)

On a properly designed hotend the heat-sink fan does not cause a temperature drop. The temperature drop typically is only caused by the part cooling fans.
My statements above relates to the part cooling fan(s).

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replaced heater with my 50w heater and temp is rock solid now thx.

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unfortunatly i am still having an issue

its not temp drop like before. more like noise or a bad connection but looking for imput

you can see by the temp graph that there are lots of spikes

have replaced 40w heater with 50w heater. nothing else changed. i have checked my connections and jiggled stuff but it doesnt seem to be the issue. could i be using to much power from the original power supply while doing moves? my printer does have a meanwell. i just did a pid tune before this print which did fail because of below min temp.
klippy.log (3.4 MB)

Temperature changes are typically slow.


Jumps like shown here: 223 → 207 → 221 within seconds are unlikely unless you have a flux compensated quantum hotend and a leak in the antimatter converter.

In such cases you should assume hardware issues. Be it wiring, defect thermistor etc.
Strong EMI effects could be a cause as well but I’m not sure if EMI effects would span 15°C or more.

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i was figuring it was hardware issue probably the thermistor. have any recommendations for good quality cartridge type thermistors?

The ATC Semitec 104GT-2 are wide spread and well-renowned.
Personally I’m only using 3-wire PT100. Class A if possible but a bit hard to come by in 3mm cartridges. These will require additional hardware.