Print head maintenance  

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Dinther
(@dinther)
New Member

Flawless run so far. Total print time only 6 days and a bit and all prints were small to medium in size. Today's almost build-plate width print won't stick so I decided to start off and re-calibrate the printer using the wizard. It suggested a nozzle clean. I decided to try to remove the nozzle only to find that the heat block that the brass nozzle is screwed into rotates so I left it alone.

Closer inspection shows wear on wires which I suspect are for the nozzle heating block (See pic below).  I probably did something wrong during assembly but before I go any further I decided to reach out here and see if anyone can deduct what I done wrong.

Secondly, any suggestions on how I should go about remediation? Should I take out the whole print-head and re-assemble it?

Posted : 07/04/2021 2:23 am
Karkovski
(@karkovski)
Moderator
Posted by: @dinther

I decided to try to remove the nozzle only to find that the heat block that the brass nozzle is screwed into rotates so I left it alone.

If the heatblock rotates with the nozzle removed, it is normal to some degree - you tighten the nozzle against the heatbreak, which locks everything in place. Provided the heatbreak is fully tightened inside the radiator.
On the other hand, wobbly heatblock with the nozzle installed means something is not tight inside (probably the heatbreak inside the radiator). The only way to fix this is to remove the hotend and reassemble it according to the manual: https://help.prusa3d.com/en/article/hotend-disassembly-heatbreak-stuck-in-the-heatsink_112677 .

 

Posted by: @dinther

Closer inspection shows wear on wires which I suspect are for the nozzle heating block (See pic below).  I probably did something wrong during assembly but before I go any further I decided to reach out here and see if anyone can deduct what I done wrong.

If you mean bare wires entering the heater cartridge, it's perfectly normal. Just make sure you don't short them with a metal tool when cleaning/maintaining the printer.

 

This post was modified 1 month ago 2 times by Karkovski
Posted : 07/04/2021 10:03 am
fuchsr
(@fuchsr)
Honorable Member

To swap the nozzle follow the instructions in here: https://help.prusa3d.com/en/article/changing-or-replacing-the-nozzle_2069

Having said that I don’t see why you’d have to remove the nozzle to clean it. From the outside use a soft wire brush. From the inside, you can use the cold pull technique. Just search the Prusa knowledge base for it. 

If you have problems with filament not sticking it’s more likely a case of dirty steel sheet or incorrect Live Z. 

To get Live Z right, don't use the in-built method, as the small square is hard to read, especially if you're not experienced. Use this instead: https://forum.prusaprinters.org/forum/original-prusa-i3-mk3s-mk3-assembly-and-first-prints-troubleshooting/life-adjust-z-my-way/

To clean the sheet properly, use hot water and fragrant-free dish washing soap. Dry with a paper towel. Before use, clean it with 90+% isopropyl alcohol. See this thread for a more in-depth discussion:
https://forum.prusaprinters.org/forum/english-forum-general-discussion-announcements-and-releases/satin-spring-steel-sheet-pla-prints-dont-stick-anymore/
Ignore the title, everything in there applies to all types of steel sheets.

Posted : 07/04/2021 2:12 pm
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