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austin.a2
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Extruder motor gets extremely hot, would heatsinks be a good idea?

May 05, 2018 2:27 am

I've recently been experiencing the same issues I experienced with my first hotend clogging and backing up filament (see hardware-firmware-and-software-help-f64 ... 5620.html for details) and one thing I've noticed is that my extruder motor gets extremely hot to the touch (like you could fry a tiny egg on it), and I'm thinking it could be a help to cool it down somehow. Would attaching heatsinks to the extruder motor be a good idea? If so, how should I go about trying it? I've seen some heatsinks on ebay that mention prusa i3 extruder in the listing but they have screw slots in places where I don't see it would be possible to attach them, or maybe I'm misunderstanding how they'd attach. below is an image of what I've found when searching for prusa extruder heatsink. I've also thought about the small adhesive heatskinks I've seen used for raspberry pi projects but I don't know if they would really make much of a difference.
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sean.h8
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Re: Extruder motor gets extremely hot, would heatsinks be a good idea?

May 05, 2018 3:02 am

I would question why your motor is running so "hard". What I mean by that is, My motor, NEVER exceeds 65c. (except for this one time...

Image


But I'm not gonna blame the printer for this... I may... have set the current to 2x the default setting, and started a 12 hour print...


I would check to make sure that the filament extrudes EASILY through the nozzle. (release tension on the bondtech, and it should be fairly easy to just "push" the filament through. If it feels "hard" to push through, you likely have a problem with your hotend somewhere, which would explain your heat.

PS: 3.2 RC2, lowers the amperage to the extruder motor, (20% or 30% give or take) so it will run MUCH cooler.


I see *NO* reason heat-sinks couldn't work.

24v @ 0.6amp = 12 watts.

My desktop = 140 watts... Never breaks 55c.

Heatsinks work. :)

(Liquid cooling, with radiator works better, in my CPU's example)
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Re: Extruder motor gets extremely hot, would heatsinks be a good idea?

May 05, 2018 5:58 am

Yes, it is better to try to find the reason for the extruder motor getting hot. A heat sink can work, but the cause of the heat problem remains, which can shorten the life of the extruder.
You probably have screwed up some details too hard. Keep in mind that there is soft plastic in the details, not hard steel.
My extruder motor works at comfortable 40 to 42°C.
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austin.a2
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Re: Extruder motor gets extremely hot, would heatsinks be a good idea?

May 05, 2018 7:41 am

sean.h8 wrote:
May 05, 2018 3:02 am


PS: 3.2 RC2, lowers the amperage to the extruder motor, (20% or 30% give or take) so it will run MUCH cooler.

What do you mean by 3.2 RC2? If theres a way to lower the amperage to the motor I'm interested.

I keep the extruder gear screws as loose as possible (stopping as soon as they catch the little door) so my best guess is this is another problem relating to something in the hotend causing problems further up.

The same thing that occured with the original hotend on my mk3 is happening with my replacement (but only after dozens of printing hours later) where the nozzle will clog about an hour into a print and then filament will wrap around the extruder gears, possibly softened by the radiating heat of the extruder motor. To me it seems like there's something within the hot ends I have received that degrades or warps over time causing issues but only after it's been used for several weeks of heavy printing. This occurs regardless of nozzle changes and with the extruder gear screws as loose as possible, printing only Prusa PLA at the standard temperature. As this is the 2nd hotend from Prusa I've received with this problem (if that is indeed what's causing it, I've spent a long time narrowing the problem down and it seems like that's where the issue most likely lies) I wonder what can be done besides just replacing them.

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Re: Extruder motor gets extremely hot, would heatsinks be a good idea?

May 05, 2018 2:07 pm

RHDreambox wrote:
May 05, 2018 5:58 am
...
Is this the same picture you've posted before about extruder motor temps? Or do you just mass produce those Iris boxes? I've been meaning to print one of those.

On the offical Prusa 3.2 RC2 firmware for the printer, the default uses less amperage to the extruder. Most guys have seen around a 10-15c drop in extruder motor temp.

When you say you are printing at "normal" PLA temps, are you on the hot side, or cold side of that temp?

The PLA I typically use is rated at 180 to 210. I find it prints TERRIBLE below 205. I generally print it between 215, and 225.

My point is, just because they say "This is the best temps" does not mean you can't go hotter. (rule of thumb, PLA hates going above 240)


Do you have an enclosure? Some guys are having heat issues with enclosures.

If all else fails, a total stab in the dark, I would advise you to try to replace the heat break with a micoswiss heat break.
https://store.micro-swiss.com/products/ ... end-1-75mm
They sell them on amazon as well, if you have prime it might be relevant.
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Re: Extruder motor gets extremely hot, would heatsinks be a good idea?

May 05, 2018 2:21 pm

Is this the same picture you've posted before about extruder motor temps? Or do you just mass produce those Iris boxes? I've been meaning to print one of those.
Yes, it's the same picture as before. I have this "iris box" as a test for my printer. When I manage to print a working "iris box" I know my printer is in top condition. (I have not yet managed :( )
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austin.a2
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Re: Extruder motor gets extremely hot, would heatsinks be a good idea?

May 09, 2018 8:37 pm

I've ordered a thermometer so I can see exactly how hot the extruder motor is getting, and I've also ordered a new heat break as that is the most likely cause of the blockage issues I'm experiencing after testing out different nozzles and filaments. On top of that I've also ordered small heatsinks to attach to the top and sides of the extruder motor. I will update with with exact heat info when those parts arrive.

As a test I put a thin perimeter line printed from one of my models on the extruder motor after printing a small 1 hour model at 210 degrees in PLA and the extruder motor is hot enough to melt through the thin perimeter lines of PLA created around objects. Both of the fans seem to be working normally, and self-test doesn't show any issues.

As of today the motor has starting making a slight grinding sound when it feeds in filament, sounding a bit like rubbing sand against a rough surface. There aren't filament particles or other debris in the extruder gears, I fear that something internal with the extruder motor has given out due to the excessive heat. I do have an enclosure but I only have it closed when printing ABS, and I haven't printed ABS since I got this new hotend, only PLA at 210-215 degrees.

I feel like I should go ahead and order a new extruder motor due to the new noises coming from my current one, but i don't see extruder motors listed on the mk3 printer parts page

Last time I went through support it took them several weeks to ship a replacement nozzle fan, I'm willing to just buy a new extruder motor to not have to deal with them.

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austin.a2
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Re: Extruder motor gets extremely hot, would heatsinks be a good idea?

May 15, 2018 2:50 am

Today I replaced my heatbreak with a Micro Swiss heatbreak, replaced the stock PTFE tube with Capricorn XS Low Friction PTFE tube, and added a 2.75 cm wide 2cm tall heatsink to the top of my extruder motor with ceramic thermal compound. I also got an IR thermometer and found the motor now gets to around 48 degrees Celsius when printing Prusa PLA at 215 degrees nozzle temp.

One change I've noticed is I'm now no longer able to fully fit the long unclogging acupuncture needles I've been using as far into the hotend as I was able to previously. I'm unsure if this is due to it being blocked by some imperfection or slight misplacement or different sizes of the new parts or if the filament is now only really melting closer to the nozzle and not softening higher up if that was the case previously.

EDIT: Still having the same filament jamming issues I was having before replacing all of those parts. I'm using Prusa PLA that worked previously and still having almost all of my prints fail because the filament either jams completely or extrudes unevenly. Using a new authentic E3D 0.4mm nozzle and all of the above mentioned new components. I made sure the bowden tube and other hotend elements that filament passes through were clear from debris, as are the extruder gears. At this point I'm out of ideas as to how to get a functional machine again, the only other thing I can think of replacing is the extruder motor itself.

Image

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Re: Extruder motor gets extremely hot, would heatsinks be a good idea?

May 16, 2018 10:43 am

austin.a2 wrote:
May 15, 2018 2:50 am
Still having the same filament jamming issues I was having before replacing all of those parts. I'm using Prusa PLA that worked previously and still having almost all of my prints fail because the filament either jams completely or extrudes unevenly. Using a new authentic E3D 0.4mm nozzle and all of the above mentioned new components. I made sure the bowden tube and other hotend elements that filament passes through were clear from debris, as are the extruder gears. At this point I'm out of ideas as to how to get a functional machine again, the only other thing I can think of replacing is the extruder motor itself.
When you installed replacement PTFE, did you taper both ends and chamfer the lower end? Also when installing, did you loosen the heat break from the heat sink by half a turn or so, push down the PTFE and lock it in place and then tighten up the heat break into the heat sink?

Also, what retraction settings are you using? I run at 0.5mm maximum retraction.

Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage or loss.

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Re: Extruder motor gets extremely hot, would heatsinks be a good idea?

May 17, 2018 1:20 am

PJR wrote:
May 16, 2018 10:43 am
austin.a2 wrote:
May 15, 2018 2:50 am
Still having the same filament jamming issues I was having before replacing all of those parts. I'm using Prusa PLA that worked previously and still having almost all of my prints fail because the filament either jams completely or extrudes unevenly. Using a new authentic E3D 0.4mm nozzle and all of the above mentioned new components. I made sure the bowden tube and other hotend elements that filament passes through were clear from debris, as are the extruder gears. At this point I'm out of ideas as to how to get a functional machine again, the only other thing I can think of replacing is the extruder motor itself.
When you installed replacement PTFE, did you taper both ends and chamfer the lower end? Also when installing, did you loosen the heat break from the heat sink by half a turn or so, push down the PTFE and lock it in place and then tighten up the heat break into the heat sink?

Also, what retraction settings are you using? I run at 0.5mm maximum retraction.

Peter
when replacing the PTFE I followed the guide at http://manual.prusa3d.com/Guide/How+to+ ... FE+tube/82 so I loosened the nozzle by about a half turn before screwing the heat break into the heat block but I didn't do any special turning for the other components because I didn't see anything about it. Do you have an illustration or photo I could use as a reference for the tapering and chamfering? Or perhaps describe in detail about how the taper and chamfer should look? I'm not exactly sure how it should be done.

I have done the "entrance smoothing" step of the guide where the inside of the top of the PTFE tube is made more hollow but I haven't altered the outside of the tube. Thank you.

Edit: forgot to mention retraction settings. I haven't altered retraction settings so they would be whatever the default is, I'm attaching an image of the retraction settings that were the default settings for mk3 in slic3r prusa edition, I haven't altered them. If there's something there that looks wrong please let me know
Image

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