Extruder motors seem to be running very hot  

RE: Extruder motors seem to be running very hot

usually a part with lots of fine details ( lots of retracts) causes the E motor to heat up. may or not be a problem depending on room temps and air temp near extruder ( enclosures make it worse)

RE: Extruder motors seem to be running very hot

Posted by: gary.s4

Lately have been running really long prints, 24 hour+ stuff, and I noticed tonight that my extruder motors seem to be running really hot (4 machines running, all very hot, only a few hours in on all machines..)... To play it safe I killed the prints rather than let them run overnight and have begun looking at the issue, which I am not sure is a problem meriting solution.

Prusa has commented that the motors are rated to 100C, so the motor itself is not at risk. Heat getting into the extruder when printing PLA seems to be the biggest issue.

I didn't measure the temps, have a laser temp measure device around here but have to find it.. It was put away and currently have no idea where that is.

Ambient temps come into play as well. (Of course, the motor will be hotter.)

I am thinking to possibly add a fan on top of the extruder motor to help cool it. Have seen some shrouds on thingiverse and seems a good idea as long as it doesn't excessively cool parts being printed or the hotend.. Can't imagine all this extra heat being generated by the motor is particularly good for the filament sensor or the  filament itself going through the gears..

I've been debating ordering heat-conductive filament specifically meant for printing heat sinks. Some folks just stick 40mm heatsinks right on the motor. There's a design on Thingiverse with a 40mm fan on top of a ducted housing that looks promising.

I am thinking that as it is the same on all machines, it is probably not an issue with idler tension or some other tuning parameter, but just hot running extruder motors..

A bunch of issues have been linked:

• General "extruder motor heat"
• Over-zealous speeds exceeding maximum volumetric rate of E3D V6 hotend, causing skips & jams.
• Over-zealous use of enclosures to print low-temp PLA without proper ventilation.
• Excessive retractions contributing to extruder motor heat.
• Increasing temps to increase flow due to extruder motor heat.
• Excessive idler tension.
• Poorly aligned filament feed path.
• Fan covers and gee-gaws interfering with airflow.
• Filament dust filters misapplied jamming filament feed.
• Poor filament feed path adding tension.
• And lately -- the Prusa custom heatbreak with 2.2mm throat intended to fix MMU issues.

During the heat of summer (for many of us) last year, there was a spate of "heat creep" problems which promptly died out later in the year. There was a noticeable spike after Prusa released the Lack enclosure article in April followed by the heat of summer.

In short: Any kind of heat that can't be vented away from the hotend (rated to 40C ambient) impedes air cooling efficiency. There are so many related factors that a problem with any one can cause a variety of feedbacks and problems.

SO my question:

Is anyone else dealing with an issue like this? Running extra cooling for the extruder motor itself? Some other solution? 

Yes. It's widespread, and not limited to Prusa. I see a lot of similar posts on the various Reddit 3D printing groups. So long as hotends are air cooled, temperature issues can be problematic.

I half-jokingly suggested we designate a "Heat Awareness Month" at the end of spring to raise awareness of these issues.

RE: Extruder motors seem to be running very hot

The typical extruder temps I've experienced are as high as 58c with 26c max ambient in the room.  A 40x40x11 mm heat sink thermal taped to the motor reduced the motor temp to under 50c.  Motor is currently running at 47.5c in a 25c room.

I've run without a heatsink at those 55c+ temps continuously for weeks with no damage to the motor or electronics (small unload pauses between multiple 24 hour prints). 

RE: Extruder motors seem to be running very hot

Printing a CG-Tech  shroud now .. Will order a set of 4 l-cheap-o 40x40x10 fans and see how the heat dissipation affects the printing..

If all is well will add them to more machines and look at better quality fans..

I haven't had any problems yet, but my work area is getting a heap warmer of late, hit 29 last night before shutdown, and I think heat creep could definitely become an  issue over the last of the summer here .. no ac.. We hit high 30s yesterday and expect more of the same, and even hotter, over the next day or two..

The extruders are running in mid-50s right now.. and that is with room at 25 C/50% humidity .. will test again later .. but I think I will probably just shutdown, all machines - not just the Prusas, until either I have a cooling solution in place or this heat wave passes.. good time to do some machine maintenance.

Thanks for the info ..

RE: Extruder motors seem to be running very hot

Posted by: gary.s4

[...] The extruders are running in mid-50s right now.. and that is with room at 25 C/50% humidity .. will test again later .. but I think I will probably just shutdown, all machines - not just the Prusas, until either I have a cooling solution in place or this heat wave passes.. good time to do some machine maintenance.

As long as the filament isn't softening and contributing to the heat feedback loop, you're probably OK. It might be a good time to try something besides PLA, so experiment with PETG, NGEN and some of the other specialty stuff. I'm not a fan of ABS, but summer seems to be optimal for it.

RE: Extruder motors seem to be running very hot

PETG Shroud from Thingiverse (link below).. 12V el Cheapo Fan from Amazon (link below) wired to a plug in 12V adapter. Max draw is about 110 mA, wanted to keep it separate to be able to move between machines as need.. Just 2 ties to cut and re-add when moving ..

Temp of extruder face with fan on .. Full draw (110 mA at max)

Machine next it, no shroud running identical job..

Looks like an option for these hot summer days ..

Extruder Shroud

https://www.thingiverse.com/thing:2975582/

Fan Motors . 12V - low amp darw

https://www.amazon.de/gp/product/B07CM1PQNS/

RE: Extruder motors seem to be running very hot

Posted by: gary.s4

[...] Looks like an option for these hot summer days ..

Thanks for sharing your results. A quick question on methodology: I've noticed significant differences in temperatures measuring at the far top of the extruder motor versus the front-facing surface. If I mount the cooler, the far top is blocked, but the front-facing surface seems to be benefitting from some cooling (perhaps the housing). I'm getting something like 34C on the surface versus 44C at the far top. I pulled off my extruder visualizer and measure the hub which was also around 44C. Is that where you're taking your readings?

RE: Extruder motors seem to be running very hot

And did you mount the fan to suck air up or blow it down? I'm wondering if this also helps pull air away from the hotend exhaust (to right of heatsink), helping the little Noctua fan out. Perhaps making this housing duct air in that direction would provide some added benefit.

I'm still on OG R2 extruder parts, so am not having major issues, but I am tracking these solutions.

RE: Extruder motors seem to be running very hot

Posted by: bobstro

Posted by: gary.s4

[...] Looks like an option for these hot summer days ..

Thanks for sharing your results. A quick question on methodology: I've noticed significant differences in temperatures measuring at the far top of the extruder motor versus the front-facing surface. If I mount the cooler, the far top is blocked, but the front-facing surface seems to be benefitting from some cooling (perhaps the housing). I'm getting something like 34C on the surface versus 44C at the far top. I pulled off my extruder visualizer and measure the hub which was also around 44C. Is that where you're taking your readings?

I see a 7-10 degree difference (C) between the front plate, not the hub, and the the top, the metal plates, on the extruder with no shroud.

Right now the readings on that one are: 47 front, 54 top.. The print has been running for almost 12 hrs so plenty of time for the heat to travel to the front.. On the one with the shround , the front is reading 35, can't get to the side..

There is room between the fan mount and the top of the extruder as you can see in this pic.

I decided first try to have the fan blowing down on the motor so it would be pulling cooling air from the cooler area above rather than the warmer area below, closer to the heating bed.

The channels seem to do a nice job of funneling the airflow across the side plates and then out the upturned exits, on the model i used.. pretty nice airflow on the exits even with such a low power fan.

I thought pointing the air flow away from the hotend would help minimize any interference..

This is an 18 hour print being run.. so I will check both the quality of the print and the shape of the somewhat thin interior fins on the shroud when the print is done and post..

Here a pic of the upturned exit..

It will be running for a while yet so if I can take any other measurement, just let me know..

I can run the fan the other way on another test print to see results and compare ..  if  interested..

RE: Extruder motors seem to be running very hot

P.S.. Thinking about it for a minute and it shouldn't be difficult to open up the sides to be able to get a temp reading.. Will play with it a bit tomorrow an give it a whirl ..