https://forum.prusa3d.com/forum/original-prusa-i3-mk2-s-others-archive/need-help-verifying-heatsink-temperature/ Prusa3D Forum Discussion Board en-US Fri, 12 Jun 2026 05:46:27 +0000 wpForo 60 https://forum.prusa3d.com/forum/original-prusa-i3-mk2-s-others-archive/need-help-verifying-heatsink-temperature/#post-40916 Mon, 04 Sep 2017 23:57:51 +0000 ...I went on and measured the temp. on the same spot as anton.k. I get around 35°C when ready to extrude. ... that's how it should be. I did the same thing at the i3 clone I build, while measuring with a thermistor, clamped between the fins of the coldend (as mentioned above), just to check if there is a difference when the extruder fan is reversed in direction (-> no difference).
got about 38°C here.]]> Others (Archive) JeffJordan https://forum.prusa3d.com/forum/original-prusa-i3-mk2-s-others-archive/need-help-verifying-heatsink-temperature/#post-40916 https://forum.prusa3d.com/forum/original-prusa-i3-mk2-s-others-archive/need-help-verifying-heatsink-temperature/#post-40915 Mon, 04 Sep 2017 23:39:22 +0000 I agree with aaron.s5 and JeffJordan regarding these devices. As it appears I have such a thermometer, I went on and measured the temp. on the same spot as anton.k. I get around 35°C when ready to extrude. The temp. bed is pretty close to what I can see on the Prusa LCD display.

Anyway, I bought it to measure the temp on my walls to find out if there is humidity in the corners.]]> Others (Archive) walter.v4 https://forum.prusa3d.com/forum/original-prusa-i3-mk2-s-others-archive/need-help-verifying-heatsink-temperature/#post-40915 https://forum.prusa3d.com/forum/original-prusa-i3-mk2-s-others-archive/need-help-verifying-heatsink-temperature/#post-40834 Mon, 04 Sep 2017 00:35:23 +0000 first a few words about "laser thermometers".
some people think that the laser beam really measures something... that's a common misbelieve, stimulated by advertisement... and completely wrong.
the process of temperature measurement is done by a small, infrared sensible chip.... sometimes with a simple infrared sensitive diode.
the laser only is a pointer, that should indicate the spot where the focus for the measurement should be located.

I've the same infrared thermometer with laser from amazon. its a real guessing-iron.

laser and measured spot only match at approx. 1m and more. at such a short distance they are way off.
so what you are measuring is most likely a part of the hotend instead of the coldend body.

one easy way to get an exact measurement of the coldends temperature is to clamp a thermistor between the lower fins of the coldend and measure the temperature through its resistance.
most of the multimeters that you can buy nowadays come along with such a thermistor and they even provide the proper temperature measurement range for the thermistor.

more expensive would be to measure it with a real infrared camera (pyrometre / bolometre).]]> Others (Archive) JeffJordan https://forum.prusa3d.com/forum/original-prusa-i3-mk2-s-others-archive/need-help-verifying-heatsink-temperature/#post-40834 https://forum.prusa3d.com/forum/original-prusa-i3-mk2-s-others-archive/need-help-verifying-heatsink-temperature/#post-40833 Sun, 03 Sep 2017 23:43:53 +0000 First, laser thermometers are notorious for mis-reading temperatures on reflective things, but those values are WAY to high.

If the heat break gets above 40C or so you will get clogs.

I presume the extruder fan (on the opposite side of your photo) is running? and you can feel the air flow exiting by the PINDA sensor? Yes, the one that should always be on over 50C.]]> Others (Archive) AJS https://forum.prusa3d.com/forum/original-prusa-i3-mk2-s-others-archive/need-help-verifying-heatsink-temperature/#post-40833 https://forum.prusa3d.com/forum/original-prusa-i3-mk2-s-others-archive/need-help-verifying-heatsink-temperature/#post-40823 Sun, 03 Sep 2017 20:47:41 +0000 Hello Anton!

Is the fan that cools the extruder on all the time the extruder is above 50 degrees C?

/Henrik]]> Others (Archive) henrik.w https://forum.prusa3d.com/forum/original-prusa-i3-mk2-s-others-archive/need-help-verifying-heatsink-temperature/#post-40823 https://forum.prusa3d.com/forum/original-prusa-i3-mk2-s-others-archive/need-help-verifying-heatsink-temperature/#post-40806 Sun, 03 Sep 2017 17:28:22 +0000 I'm currently suspecting heat creeping up the extruder. Can somebody please verify my temperature readings? E3D v6 docs say heatsink should be "cool to the touch". My Laser thermometer says it ain't so.
Printing PLA, during the first layer I see about 145 C on the lowest fin. The temperature drops 10-20 degrees for the following layers. The center of the heatsink easily reads 60-80C
Is this expected?

]]> Others (Archive) anton.k https://forum.prusa3d.com/forum/original-prusa-i3-mk2-s-others-archive/need-help-verifying-heatsink-temperature/#post-40806