Procedure for shutting down the printer for an indefinite period (cleaning and emptying the nozzle?)  

RE: Procedure for shutting down the printer for an indefinite period (cleaning and emptying the nozzle?)

Posted by: @simearth

Hello,

 

I am a new 3D printer user for few time. I currently print my first parts (I own a i3 MK3).

 

I have some very simple questions but I don't find answers in the Prusa Printing Handbook :

- After a print, if I don't intend to print for a while, which is the procedure for shutting down the printer ? (Mainly about the filament presence and the cleaning of the nozzle).

- If I print with PLA, I read it's better to store the spool in its bag (to protect against humidity, etc...), so I cut the filament near the top of the extruder. Is it necessary to clean the nozzle each time I remove the spool ? Or is it possible to leave the piece of filament inside the nozzle, until the next use ?

 

Thank you in advance,

Hello and welcome to the Prusaforum!

After printing it is sufficient and is also recommended to unload the filament and store it dry. Ideally you should also clean the nozzle with a "cold pull":

RE: Procedure for shutting down the printer for an indefinite period (cleaning and emptying the nozzle?)

Hello Karl,

Ok, thank you for your answer !

RE: Procedure for shutting down the printer for an indefinite period (cleaning and emptying the nozzle?)

You shouldn't cut the filament above the printer every time. It's not harmful, but it's a waste of the filament. If you press in on the knob next to the display on the printer, it goes into the menu, and one of the options there is "Unload Filament". Select that, and then the material you have in there, and it will heat up the printer and reverse the extruder gears so that you can pull the filament out all the way from the nozzle. There will still be a little bit of plastic that was melted stuck in the nozzle, which is what the cold pull Karl mentioned is for, but most of it comes out filament-shaped, ready to be used again next time. 

Also, I don't cold pull every day. If I know I'm going to go back to using the same material the next day, I'll just unload it and put it in a bag (with desiccant, the 'Do Not Eat' packet that came with the filament) for next time. I'll only do the cold pull if I know I won't be using the printer for more than a week or something, if the nozzle starts to clog, or if I'm switching to a different material that needs a different hot end temperature. Some people do cold pulls much more than I do, but I haven't seen any issues from not doing them every time I switch spools.

RE: Procedure for shutting down the printer for an indefinite period (cleaning and emptying the nozzle?)

What is 'a while', as in how long the printer will be idle?  Is it days, weeks, months?

I've gone a few days without use, without unloading, with no issues.  I have not gone a week so far, but with 1-2 weeks I would be comfortable leaving the filament loaded.

For a couple of months, I would probably unload, maybe do a cold pull.

The only issue I've had leaving anything in the printer is when I did a couple of PC Blend parts and left it overnight.  When I tried to load PLA the next morning, it would not go, obviously because the PLA temperature was insufficient to flush out the remnant of the PC Blend.  A quick pre-heat to 275 or so followed by a 'flush' with the PLA cleared it out nicely.

RE: Procedure for shutting down the printer for an indefinite period (cleaning and emptying the nozzle?)

Call me lazy, but I leave the last used filament in my printers - mostly PETG as this is my preferred filament. This have worked for years.
If a roll of PETG starts to make a cracking sound due to moisture or starts to ooze too much I dry the hole spool in the food drier.

Exception to this is the more exotic filaments like Nylon, Bridge and PC, which I always unload after use and put in plastic bag with a moister absorbing bag.

RE: Procedure for shutting down the printer for an indefinite period (cleaning and emptying the nozzle?)

I just leave the last roll on the machine. My activity often comes in bursts with a few weeks of downtime between prints.

The worst side effect is that the filament can sometimes snap close the print head. This only happens with a nearly empty spool where the tightly wound portion gets pulled straight and sits for a few days. It rarely happens with a full spool. I lose about 6" of filament and risk the end getting tangled. 

I am in a relatively low humidity area and only print PLA.

Steve