i’m making a trying to make a list of all the possible causes for a blocked\clogged hotend. any input ?
- Nozzle too close to print bed.
- Material heated for prolonged duration without extruding.
- Printing at insufficient or over sufficient temperature.
- Burred or damaged nozzle.
- Over extruding.
- Part warping upward.
- Poor material quality.
- Damaged teflon tube inside hotend.
- Too much tension on filament
- Contaminated filament, Example moisture and dust.
-Filaments (eg: Laywoo-D) that contains particles larger than the nozzle diameter.
-Extrusion speed exceeds the hotends ability
-Extruder fails to feed filament
-Excessive retraction length
Poor material quality or unfiltered.
If there is a teflon tube in the hotend, damage to the teflon can cause all manner of complications that lead to a blocked hot end.
@Jon_Gordon but what do you mean by unfiltered, first time i’ve heard the term.
If you have used a different plastic in the hot end previously and the old plastic hasn’t been properly cleaned/purged.
Dirt/hair/dust stuck to the filament being dragged into the hot end.
Plastic that has absorbed too much water (stored in conditions of high humidity). Can lead to weird extrusion or jamming due to expansion.
@Stuart_Young thanks for your help.
Filaments that contain particles (eg: Laywoo-D, etc) where the max size of the particles are larger than the nozzle size of the hot end. eg: Laywoo-D tends to have a max particle size of 0.45mm, whereas the average size is much lower. It might work for ages with a 0.4mm nozzle but at some stage you will probably get a clog.
On metal hotends, too much pressure build up in hotend can cause molten plastic to push back up into cold zone and stick to metal above the melt zone- since it will cool
Filament loading can get caught on ridge of inner barrel if edge isn’t beveled. The passage not smooth.
Filament diameter too big. Sometimes filament is out of spec or swells. Sometimes only a small section
Temp too low so filament isn’t melting. Either set too low or thermistor reads too low.
Set screw on drive gear is loose and drive gear spins.
Motor not pushing- either overheating or a broken wire.
Firmware allows cold extrusion and it hasn’t heated yet
gcode damaged / temp is set too low or not a all
Hotend wiring problem- not heating
Extrusion speed exceeds the hotends ability- even though it reads hot enough, the filament isn’t in the heater long enough to heat up. Thermistors read the heater, not the filament.
Tip is too small for exotic filament and clogs- like carbon fiber or metal filled filament
You are set for pla, but accidentally loaded abs 
Filament breaks just above drive gear
Hotend overheats and softens plastic in the cool zone, swells and jams
Heater barrel is well used and scored to the point of being abrasive. Too much resistance
You switched filament after a filament break in the barrel and angle of new filament cut wedges the filament already in the barrel up against the side… Instead of a clean push straight down, it wedges sideways
Too little pressure on idler wheel so drive gear doesn’t find purchase
Clogged teeth on drive gear
Worn teeth on drive gear
Too long of path on filament feeder tube
Kinks or too tight of a radius in filament feeder tube.
Kink in filament is caught on something
Filament tied in knots on spool or wedged tight under other filament on spool
Spool caught on something and won’t turn to feed more filament… Usually chews a spot in filament
Drive gear and idler so tight it deforms filament, squishing it oval out out of shape do it won’t push through
-I’ve experienced all of these over the years.
Brook
@Brook_Drumm WOW, thanks a million Brook.
Can’t believe nobody mentioned this but you’re trying to print flexible filament and your drive gear isn’t close enough to your hotend or you don’t have a guide to it.
Excessive retraction length that can lead to have molten plastic in the cold chamber (mostly an issue with PETG).