Types of Clogs and How to Avoid Them
While the causes of 3D printer clogs are numerous we can classify them into 2 main categories; Nozzle Clogs and Complete Clogs. If filament is extruding but only partially, then it is likely that your nozzle needs cleaning. This is evidenced by filament curling up as it exits the nozzle or by layers of your print seeming under extruded. If you can't load your filament or it's already loaded and doesn't extrude at all, then you have a complete clog. Once you asses the type of clog you have you can find the applicable section below for help.
The article linked HERE is a straight forward list of best practices to help prevent clogs before they start. Most notable is the temperature settings for your plastic.
By heating up the nozzle and poking around in tip of the nozzle with the provided acupuncture needle we can resolve many nozzle clog issues. The details of this process are outlined on the Prusa website, linked HERE.
We can take different approaches to unclogging your machine depending on where in the system your filament is getting stuck. If you can't unload your filament, try Force technique linked HERE. If that proves unsuccessful, move on to the High Clog technique below. If you have cleaned the nozzle but still can't stick a needle more than 1 inch up into the nozzle tip, then try the Body Clog procedure below.
By heating the extruder up to 290 degrees Celsius [main menu,settings,temperature,nozzle] and un-mounting the small fan on the left side of the printer head assembly, we are able to create enough heat to pull the filament out from the top of the assembly. This technique is demonstrated in the video below, and has proven successful in the field. I'm a fan of watching these videos at 1.5 x speed until the content becomes pertinent.
PLEASE NOTE: There is a risk involved in using this technique. By heating up the extruder to such a temperature we risk melting the nylon tube inside of the assembly if it is exposed to these temperatures for too long. It is advisable to wait until the unit reaches 290 degrees, immediately make a firm attempt to pull out the filament, and shut the machine down immediately after. As always, be careful around hot extruders.
In a slightly trickier procedure we can unclog extruders that have plastic stuck where the teflon tube meets the top of the heat break(purple box pictured above), about 1 inch up from the tip of the brass nozzle (where the melted plastic come out). The original intent of the video below was to demonstrate a teflon tube change, but it is helpful to watch for its disassembly instructions, as the disassembly will allow you to reach any clogs deep in the system and visually inspect for damage to vital components.
PLEASE NOTE: This repair will take time if you have never tried it before. Allow yourself enough time to be patient and careful. It is easy to accidentally break the thin wires that connect the thermistor to the extruder assembly so be gentle when loosening the nozzle tip and handling the components.