Hot end blocked--what to do?

I'm printing in PLA at 195c or around, but today my extruder doesn't extrude. It kind of went back sometimes when it extrude unless I press the filament at the same time. The other times it works ok but it extrude less than it is supposed to do even when I press it by hand.

Seems like a lot of people have experienced the same thing. But I'm not sure what to do with mine...

Looking for advices, thanks.

Edited 1 time(s). Last edit at 04/19/2014 08:19PM by jpan.

Quote
jpan
It kind of went back sometimes when it extrude unless I press the filament at the same time.

Most of your post doesn't make sense to me, please reiterate your problem.

Clean the splines on your hobbed bolt, feed fresh pla in, and slowly extrude small mounts until it clears.

If that doesn't work then take apart the hot end and soak the nozzle in acetone for a good 24 hours then try again.

After this happened twice I ditched my aluminium headed J head mk v and switched to a brass tipped E3D head and have had no problems since.

Possible causes:

Extruder is slipping, hobbed bolt is filled with material (clean it)

Hot end plugged up, remove and clear out. Since you supplied no information no instructions can be given as model is not known.

Temp too low or bad PLA. Is it the same PLA you have used already in the same color from the same supplier? It may need more heat or it may be junk.

PLA has moisture in it. While I rarely print PLA I have heard it can cause many problems as it absorbs moisture out of the air. Dry it out (search for instructions).

Quote
A2
Most of your post doesn't make sense to me, please reiterate your problem.

Sorry but I'm not a native English speaker. I'll do as best as I could to write my posts.

My extruder is MK8. (something like this: I use thermistor though)

I have token my nozzle off and found that there are something in it and I can't remove it. I tried to heat the nozzle up and sort of dig it with an iron wire and it didn't work. I think that's the reason why I can't extrude.

Thanks

Edited 1 time(s). Last edit at 04/20/2014 11:13AM by jpan.

Try Dodgey99 suggestion:
take apart the hot end and soak the nozzle in acetone for a good 24 hours then try again.

After your problem has been solved, consider adding a filament lubricator (a few drops of canola oil), and filter.

Threaded Filament Dust Filter - Replicator 1,2 & 2X
[www.thingiverse.com]



Edited 1 time(s). Last edit at 04/20/2014 04:43PM by A2.

Just side note.. he is using PLA.. acetone won't desolve the blockage. Or at least that is my understanding.
I always womdered if boiling the nozzle would work or steam, though i don't know how you would steam clean it.

I'm looking at a similar problem with a blocked hot end from PLA and soaking in acetone does help. Maybe it's just the PLA I'm using, but I can see white streams of dissolved plastic falling off the print head when it's in the acetone. Hasn't fixed my problem yet so YMMV, but it's work a try.

Here is what I have done >

Using a sharp drill bit and just finger torque on the bit I spin it back and forth between my fingers on the inside of the nozzle. DO NOT use a power tool for this.

McMaster Carr also sells the high speed steel drill bits in the .5 mm size i needed to clean out the end of the nozzle. This drill requires a pin vise and patience. Again work from inside the nozzle, to avoid messing up the tip. Anything else jammed through your nozzle will be ineffective or render it as scrap.

Insert filament, heat up to temp, push a little bit through (if possible), cool down to ~130, pull out filament.

This can pull out the junk if you are lucky.

Also you can dismantle the hotend and stick just the metal tip (no thermistor or resistor should be attached!) over a hot flame to burn out junk.