Another really hot extruder motor  

RE: Another really hot extruder motor

My extruder tension screw protrudes about 1mm from the cover. I'm using a Mk3 (not Mk3s) extruder though, so there may be some differences.

Are you hearing any noises from the extruder? Any skipping?

• High ambient temps? Room hot or in enclosure?
• Hotend cooling fan installed correctly? Blowing? Heatsink fins clear and airflow good?
• Filament feed path clear? Filament not snagging?
• Open the extruder and inspect for anything rubbing or out of alignment.
• Does the idler gear on the door spin freely? Not loose or axle hanging or jammed?
• Thermal paste applied at top of heatbreak at interface to heat sink?
• Lots of retractions on the print?

Check those items out.

RE: Another really hot extruder motor

@bobstro

No noises at all, no skipping.

-Happens at ambient temps between 20-30 degrees, well ventilated
-Hotend cooling fan installed correctly (Noctua sticker not visible), heatsink fins clear (printer was assembled 3 days ago)
-I don't see any issues with filament path
-Idler spinning freely, not loose, nothing jammed
-I haven't applied any thermal paste anywhere on the printer and can't find anything about it in the manual
-Yes, print has a lot of retractions, but that shouldn't make it so hot. I mean it's REALLY hot (I don't have a sensor to actually measure it, but it's WAY hotter than print bed @60 degrees C)

RE: Another really hot extruder motor

"Hot extruder" is one of the common complaints along with "jams" that often fall under the topic of heat creep. Heat creep can occur low in the hotend (often due to lack of thermal paste) or higher up in the extruder (often due to printing in a hot enclosure reducing the efficiency of the air cooled heatsink). The result is that PLA in particular with its low melt temps can soften and start to stick or jam. As the extruder works to push the filament it will generate heat. A couple of final thoughts:

• Be sure filament feeds through the hotend without obstruction. Open the extruder, heat to printing temps and verify you can push filament down from the top and that it melts and extrudes smoothly. Do some cold pulls if not. Check top of PTFE tube below Bondtech gear for damage.
• Consider replacing your heatbreak. Prusa uses a 2.2-2.0mm step in their modified version of the E3D V6 heatbreak. I've personally had no issues, but a lot of people have replaced this part (relatively easy and < $20) and reported resolution of their problems.

If you do opt to replace the heatbreak, consider:

• Be sure to use thermal paste at the TOP of the heatbreak at the interface to the heat sink (and NOT a the BOTTOM where you'll pull heat out of the heater block and make things worse).
• Consider a titanium or bimetal heatbreak which uses a poor heat conductor between the hot and cold zones to isolate heat and reduce heat creep up into the heatbreak.
• Consider a nickel-plated copper heater block while you've got things torn apart. A bit more efficient and tougher than aluminum.
• Consider adding a silicone sock to keep crud off the hotend and stabilize temps.

RE: Another really hot extruder motor

@robi1kenobi

Looks like you've checked most common issue. I would suggest to get a temperature measuring tool and contact PR live support. If you really get >80C temp on the motor in only 1-2 minutes print time then something is off. Either too much friction (motor needs to work really hard) or maybe something else.

It's very common on the MK3 printer to get a hot extruder motor but not that hot and not so fast.

RE: Another really hot extruder motor

So I waited for print to finish and unscrewed the screw that holds the extruder door, it's now 1-1.5 mm higher than the printed part, 15 minutes in, a LOT of extrusions, it's barely warm. Will check in half an hour and see if it gets hot again.
Thanks for the help guys (I learned today I should follow reason, not instructions lol)

RE: Another really hot extruder motor

Yeah, it's still hot as f**k. I'll try to borrow an accurate temp meter and measure the exact temperature.

RE: Another really hot extruder motor

We now it' s hot, no need to measure, and for the motor it is no problem.

You could try to blow air on the motor, but not on lower part of printer, if this is possible I do not now, but on https://www.thingiverse.com/   you can find a extra fan for on the extruder motor(blows to the top), I have this installed, and yes it cools it down very good, I use a extra power supply(I have also a filter in the enclosure with a fan), the cable of the fan  I have on the outside of the cable bundle of the printer(so i do not have to release all the cables).