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Blocked nozzle

Posted by tmccar 
Blocked nozzle
July 12, 2019 01:04PM
I have a Tevo Tarantula with a Bowden extruder and am finding that the filament is getting blocked frequently.
I thought it might be a problem with the nozzle, but I fitted a new one and the same thing is happening.
I have set the extruder temp to 240 degrees.
Re: Blocked nozzle
July 12, 2019 01:15PM
What material are you printing?


http://www.marinusdebeer.nl/
Re: Blocked nozzle
July 13, 2019 02:17AM
PLA
Re: Blocked nozzle
July 13, 2019 03:22AM
240 for PLA is way too hot in most cases. I would start with trying to print at 210ÂșC. Try that before anything else smiling smiley


http://www.marinusdebeer.nl/
Re: Blocked nozzle
July 13, 2019 05:36AM
I tried printing at 210 degrees but it's still getting blocked.
Re: Blocked nozzle
July 13, 2019 06:47AM
Is the hotend fan running? It should be running any time the hot-end is hot.


Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: Blocked nozzle
July 14, 2019 03:34PM
Make sure their is no gap at all inside the heat block between the nozzle and the heat break. If their is a gap it will block your hotend up over and over again.

The reason is you would get a little 'washer' of plastic form between the nozzle and the heat break, or just leaking plastic, either is bad.
Re: Blocked nozzle
July 15, 2019 04:07AM
The hot-end fan was not running.

Please explain "heat break"
Re: Blocked nozzle
July 15, 2019 04:44AM
Quote
tmccar
The hot-end fan was not running.

Please explain "heat break"

A heat break is a material that is placed in between the hotend heater block and the heatsink of the hotend to prevent heat creeping up into the heatsink and the machine parts. The heat break also makes sure that the transition zone for the plastic to melt stays as short as possible.

See it this way: if heat creeps up the hotend, the filament starts to melt outside of the hotend heater block and will cause issues because it usually is only hot enough to make the filament pass the glass-transition temperature. This causes a 'plug' (term), that wedges itself, usually right above or in the heat break zone.

The cooling fan is supposed to cool down the heat sink to circulate the air away by flowing air over the heat sink. Convection.

The heat break is the thin metal tube part on the E3D v6 hotend in between the heater block and the heat sink:


Edited 1 time(s). Last edit at 07/15/2019 04:47AM by Ohmarinus.


http://www.marinusdebeer.nl/
Re: Blocked nozzle
July 15, 2019 05:09AM
Thank you for that detailed explanation!

I am finding that this last section of filament expands and gets stuck in the tube. But maybe that's because it's blocked up ahead at the nozzle?

Re: Blocked nozzle
July 15, 2019 07:21AM
It also looks like the ptfe tube doesn't have a straight cut, this can cause issues on itself.


http://www.marinusdebeer.nl/
Re: Blocked nozzle
July 18, 2019 08:45PM
Once you get the tip of your ptfe tubing on the square, you may want to check your coupler. The ones included with the Tarantula are of low quality and may slip out, so the force of your filament pushing against the tubing may push it away from the nozzle. Also, the stock pinch extruder is crap and the Chinese MK8 style nozzles tend to require more extrusion force than E3D nozzles, so make sure to install the Titan clone if it was included with your kit (it was with mine). If you can afford it, getting an E3D Lite6 hot end is worth it--it made my Anet A8's print quality perfect--filament passes through with relatively little force required and the thick ptfe lining prevents heat creep vs the full E3Dv6.
Re: Blocked nozzle
July 20, 2019 05:34AM
Ok, I will try out the Titan when I get a chance, thanks
Re: Blocked nozzle
July 25, 2019 07:34AM
Can I swap in the Titan where I have the standard Bowden extruder at the moment?
Re: Blocked nozzle
July 25, 2019 09:27PM
Yes, the Titan comes with a bowden adapter. You will have to re-calibrate your e-steps.
Re: Blocked nozzle
July 26, 2019 06:08PM
Quote
tmccar
I tried printing at 210 degrees but it's still getting blocked.

When I have run 240 degrees on hotends that are NOT all-metal, it frequently bungs up the PTFE liner in the heat break, and I replace the heat break, if possible with an all-metal one. This has happened to me with three printers, including my Tevo Tarantula. On the latter I replaced the hot-end with an E3D Chimera dual-filament Chinese knock-off. The Chimera has all-metal heat breaks. Take your hot-end apart and examine the liner, if it is all wrinkled up (mine always were) then replace the heat break and you'll be back in business. Take off the nozzle and look into the heat break. You will see a white liner in there, that is the thing to examine for heat damage.

I think that frequently our hot ends are running hotter than we think. Since we can't zap the heater block with a non-contact IR temperature measurement, we never know for sure... Frequently you can get a nearly exact heat break for your hot-end that is "all metal". It may not be perfect, but you'll never get clogs again due to a deformed PTFE liner in the heat break again!

DLC

Edited 1 time(s). Last edit at 07/26/2019 06:10PM by dlc60.


Kits: He3D K200 Kossel, Folgertech Kossel 2020 upgraded E3Dv6, Anet A8 upgraded E3Dv6, Tevo Tarantula enhanced parts and dual-head
Scratch: Large bed Cartesian, Linear slide Delta, Maker-Beam XL Micro Delta
Re: Blocked nozzle
July 26, 2019 09:51PM
To prevent clogs when changing filament, I start with the hotend cold, turn on the heater, and start pulling on the filament, so that the old filament comes at the lowest temperature possible. This tends to minimize the amount of filament left in the hot end. When the hot end reaches temperature, I can add the new filament.

PLA tends to carbonize and clog the tip if left hot too long without flowing. The hotter the lest time it takes and 240C is too hot for PLA. I use 200C for PLA and 240 for ABS.
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