Sudden issues with clogged extruder.  

New Member


currently I have following problem:
The printer was working very nicely and produced good quality prints.
Then it started with layer seperation in one print. And from this print on I also had very big issues with a clogging extruder; the molten head of the filament not doesn't get unloaded after the print, snapping of and getting stuck within the connecting part between heater block and heatsink.
Every. Time.

When I remove the block and start a print the filament will usually underextrude in a very uneven and thin manner. I tried the common ways to combat underextrusion but to no avail. It won't even stick to the heatbed as its just a very thin line of filament.

Never changed any settings. Tried proven gcodes. Swapped the nozzle. Swapped the entire hotend.

Maybe someone has an idea what the problem is.

Have a nice day/evening 🙂

Posted : 27/11/2019 6:25 pm
Famed Member

For the a blockage below the Bondtech extruder gears but above the hotend, try this:

  1. Raise Z
  2. Heat nozzle to 285C
  3. Open the extruder housing
  4. Insert a 1.5mmx150mm rod down through the top, past the Bondtech gears and into to PTFE tubing and try to push the stuck filament down into the hotend to melt out. Don't push too hard, and brace the extruder assembly to avoid twisting. 
  5. If you can't push the blockage down, remove the nozzle (use the E3D instruction) and insert the brass rod up past the nozzle into the hotend. Hold it with pliers and let it warm up as you push gently up. The blockage will hopefully soften and pop up into the extruder where you can grab it with needle-nose pliers.

If this doesn't work, you may be looking at a tear-down. However, I haven't had to do one in 18 months.

Incorporate cold pulls into your regular maintenance routine, especially whenever you swap from hotter materials (e.g. PETG at 230C) to cooler materials (e.g. PLA at 200C). Remnants of the higher-temp material can cause partial blockages that might explain your problems. Cleaning filament (I recommend eSun) is recommended as it will work with a wide range of materials, so any that gets stuck will simply extrude out even if you print PLA at colder temps next. Your hotend swap presumably included a new nozzle, but keep spares! They are consumables and a swap is often an easy solution.

For prints not sticking, look at adhesion and Live-Z issues. Be aware that the textured sheet has mixed reviews with PLA.

Heat is behind many failures...

  1. If you are experiencing jams above the hotend, evaluate whether heat might be an issue. The E3D V6 extruder is air cooled and rated to 40C ambient temps. If you don't have good air circulation or are printing in an enclosure, PLA can soften high in the extruder mechanism.
  2. If you are experiencing jams lower at the hotend, heat from may be creeping up into the cool zone and softening filament prematurely. Prusa uses a "Prusa-fied" heatbreak with a 2.2-2.0mm step that has been blamed for compounding this problem. Application of thermal paste at the top of the heatbreak where it threads into the heatsink is also recommended. 

In general, look for friction in the filament feed path. Check to make sure the Bondtech idler gear spins freely and is securely mounted. Make sure no filters or stands cause filament drag. See if the filament path down through the top, past the Bondtech gears and into the PTFE tube is clear (hex wrench of 1.5mm rod will help test). Did you swap the PTFE tubing when you swapped hotends? It can be damaged and require replacement.

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 27/11/2019 10:24 pm
Active Member
Posted by: @bobstro

Application of thermal paste at the top of the heatbreak where it threads into the heatsink is also recommended. 


That sounds like the solution for you. I had similar problems and that was my solution. Filament gets too hot too quickly and jams with little thermal paste.

This post was modified 3 months ago by Rams
Posted : 30/11/2019 8:32 pm

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