Nozzle Blockage

Hi everyone,

I seem to be running into a reoccurring Hot end nozzle blockage problem.
I found somewhere on these forums that one solution is to drop the temp down to 100° and draw it back, along with whatever crap is blocking it, which works sometimes, other times I have to dismantle the hot end to unblock it. Either way it'll flow just fine for a layer or two then block again. I've used 2 different filaments too, so I can probably rule that out.

Has anyone else come across this ?

Thanks

Are you sure it is a nozzle blockage? It could be that the filament feed is malfunctioning, which other people have reported on?

I'm not sure which it is now, I had assumed it was nozzle blockage but maybe it could be the filament feed, what happens is that I hear a *click click click* from the extruder gears like they are stuck.
When I've had it all apart the extruder itself seems fine, filament passes through no problem It just seems to be stuck in the nozzle is all.
I've been working on this machine for 6 weeks, I'm so close to printing something useful, I can feel it, Just one last hurdle surely...

The clicking (especially if you can see the bowden tube flexing at the same time) suggests that it might be a blockage - when you retract the filament after one of these events, is it gouged out on one side? (you get this when the wheel grinds as it tries to push the filament through but can't).

I had a blockage that I managed to drill through a while ago - it wouldn't pull back out, I guess it was a fleck of PTFE stuck right in the orifice. You can buy a set of microdrills from Maplin that may help.

Ray

There is flexing of the Bowden tube though can't see any gouging, but it is definitely struggling to push the filament through.
I'll get myself a new nozzle and see if that solves the problem, and i'll get some of them micro drills from maplin a man can never have too many drill bits.

I have the exact same problem, what is the best way to clean it?
[e3d-online.com] could something like this be a solution?

I too had extrusion problems initially.
They proved to be problems I should have spotted during assembly.
1. the hole in the extruder body for the motor spindle was not concentric, so the shaft was rubbing.
2. the motor spindle was not perfectly square with the extruder body, so the spur gear was rubbing (and wearing) an arc of about 45 degrees.
The first problem was sorted with a bit of filing.
The second required an extra washer on the big wheel spindle to bring it out an extra 0.5mm - and then not push the small gear down to the extruder body.

You should be able to easily extrude filament (when up to temperature) by turning the big wheel by hand (with the motors off)
If it is quite difficult to turn, then check out my two problems above
Greg

---

Ormerod #17

Well I replaced the nozzle, still didn't help though.
I'm stumped, extruder drive seems fine, Bowden tube looks all clear, and I've tried various filament, and there appears to be no problem in heating.

KevM - just to clarify, do the gears stall when you get no extrusion? Can you turn off the motor and push filament through? It's maybe a long shot from your prioir description, but worth checking if you're stumped: If they continue to move round and round it could be that the teeth on the hobbed nut are filled with plastic dust and are slipping on the filament - to check you can undo the bolt holding the larger gear in place then extract it - you'll need to snip the filament either side of the extruder and pull it through by hand first or it'll prevent the hobbed nut and the bolt coming out. I've sonicated mine when it's happened, but a toothbrush should clear the grooves.

Ray