Hot End Blocked?
February 12, 2016 05:31PM
Had a nightmare evening printing today, started off struggling to extrude, but got the in the end, then parts wouldn't stick to the buildtak and then once I'd got a print to stick and got 95% of the way through the build it stopped extruding! Not happy as I was printing something for my wife for Valentine's Day. But the weird thing about it is that I cannot get the filament out of the hot end, whether it is hot 220/230C or by heating to 220 then down to 100, cannot retract it with the motor or by hand with the motors disengaged.

Has anyone else had this? I've had a few issues with extruding so the next step for me is to disassemble the Bowden and hot end to check that it's running smooth. Not sure how I'll get the filament out though, if it won't come out by heating on et machine it might be time to disassemble and bake it in the oven and shove a wire up it.

Very frustrated!
Re: Hot End Blocked?
February 14, 2016 12:09PM

I don't know if this helps at all, but I've just had to do exactly the same thing because my fan stopped working and the whole of my hot end got jammed up.
I released the clip holding the brass bit into the extruder motor end and then hit extrude a few times which pushed the Bowden tube out of the hole, then hit extrude a few more times to give me a bit of slack. I cut the filament with side cutters, disconnected the multi-way connector near the hot end, unclipped the 6 arms going down to the hot end and pulled it all out. I pulled the push on connectors off the thermistor, removed the heating element, undid the brass locking nut near the nozzle unscrewed the alu block and nozzle, and pulled the 300mm of filament out of the Bowden tube from the bottom. Then, with a pair of long nosed pliers I held the nozzle and popped it over the gas hob whist pulling on the free end of the filament. Once the plug had come out, I got another bit of clean filament and pushed it through the hot nozzle to make sure it was all ok before reassembling. Whole process took about an hour including a test build.

Don't know if anyone else has better advice, but that's my shot having had a go at it a couple of days ago!

Hope that helps...


Re: Hot End Blocked?
February 14, 2016 03:41PM
Another solution, which may be faster and I have applied to a nozzle built similarly to the Fisher (M4 full nozzle in stainless steel):
I don't like to dissassemble the wiring, as this may drive to future failures

- remove the bowden tube by unscrewing it from the hotend
- disengage the effector from arms
- heat at maximum temperature for the filament and pull the filament, that may need strength, so take care of the way you maintain the hot hotend and beware while the filament breaks. Leather gloves may help.
- let cool down
- set a 2mm diameter bit in a dremel
- Drill carefully by rotating manually the mandrel (don't run the dremel electrically!)
You only need to remove plastic from the non heated zone, so you will be far from the end of the nozzle and as the hotend is in stainless steel, usin carbon steel bit limit the risk of degradation.
A tape around your bit will help know what depth you are.

Edited 1 time(s). Last edit at 02/14/2016 03:43PM by PRZ.
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