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mattias.h
(@mattias-h)
New Member
Hot end heating problem

Hi everyone, I need some help troubleshooting/diagnosting my problem.

When I try to print I get a very small "drizzel" of PLA coming out and after a while it starts feeding properly. I unloaded my filament and then loaded it again and it didn't want to get loaded. I pulled it out and it looked like this:

https://imgur.com/a/M9dk1My

I assume that means that the temperature wasn't enough to actually melt the PLA properly. The self test runs fine, sometimes if I run the self test while it is still hot it fails however - not sure if that is intentional. I think that my hotend isn't hot enough, but I need help to diagnose the problem. I have a IR -thermometer that I assume is kinda inaccurate but it shows 190degrees (pre-heated up to 215).

I am using a Original Prusa i3 Mk2 firmwire is up to date but I did recently change the whole extruder including hot end, thermometer, heat-sink and heating stick-thingy.

Any help would be appreciated.

Posted : 27/07/2018 8:23 pm
JoanTabb
(@joantabb)
Veteran Member Moderator
Re: Hot end heating problem

Uuuuuuuugllllyyyyyy!.. 😯

that looks long and grotty...

you have it to hand,...

what you should have is a small blobby bit at the bottom, and about 80mm of filament un melted, with light tooth marks off the hobbed wheel of the extruder...

what you seem to have is a fairly long blobby bit then a stretched bit, then a thickened bit with extruder hobbed wheel tooth marks on it

if this is the case, it looks like you are getting heat soak up inside the heatbreak

the heatbreak is supposed to create a sharp transition between the heat block area, which you want to be as hot as the preferred melt temperature,
and the cold end inside the heatsink, where the cooling fan blows...

if the left hand fan is not working, or it is on with the sticker on the hub facing outwards, then you will get reduced, or zero cooling, which can cause heat soak...

or, if you turn the printer off after finishing a print, without letting it cool down with the fan, you can get heat soak?

or, it could be incredibly hot in your workshop....

or. your extruder motor might be overheating ( but I haven't heard of that on a mk2)

so, my suggestion,
have another go, and see if any of these conditions may be present!

best wishes Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Posted : 27/07/2018 9:00 pm
coopster
(@coopster)
Eminent Member
Re: Hot end heating problem

thanks for your answer… it actually helped me solve my problem on my post!

Posted : 30/07/2018 8:43 pm
JoanTabb
(@joantabb)
Veteran Member Moderator
Re: Hot end heating problem

Exelent!

Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Posted : 30/07/2018 11:39 pm
mattias.h
(@mattias-h)
New Member
Topic starter answered:
Re: Hot end heating problem


best wishes Joan

Thanks for your answer Joan!

The fan is working and I have previously printed quite a lot with the fan so I don't think it is that. It isn't incredibly hot in my workshop between 18 and 25, surely that is fine? I have had it in the same place too before with the same temperature so it should be fine.

I get this problem every time I try to load a filament. I do the normal procedure of preheating it with the inbuilt preheat option and then load filament. The filament goes in and it seems fine but after a second or two of extruding filament the motor starts hacking and you eventually it stops, then when I unload the filament again you get the filament that looks in the OP.

Based on this and what you said it does sound like it could be some kind of heat leakage, but I wonder why and where. Do you have any other idea what it could be?

It could also be that the heater doesn't get hot enough, that the thing showing the temperature is off somehow. Is there a way I can check to see if all that is working as it should? Preferably without going out to buy a thermometer that can measure up to over 300 degrees. 🙂

Thanks

Posted : 31/07/2018 7:27 pm
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