Unclogging Smart Extruder

[flynhi808]

MakerBot just sent me a replacement extruder without requiring me to send back my old extruder. I want to unclog that old extruder so I can have an extruder to use when the new one clogs. 

I have heard of the guitar string method but does anybody have a certain one to use?

Happy Printing,

flynhi808

[Robert Nee]

I might try a piece of 0.032" piano wire. You can get it at amazon or any good hobby store.

[Scott Booker]

That certainly won't fit a .4mm nozzle.......

[Jetguy]

I know there are lots of new folks so I'll try to re-explain stuff that we've gone over a few hundred times before.

#1, it's almost NEVER a nozzle clog. As long as you don't cook and burn the filament or have dirt, dust, and lint follow the filament into the extruder, and also don't get filament with dirt embedded in it, then the nozzle should never clog.

#2 On the 5th gen, the #1 cause of ALL clogs is BEFORE it even goes into the hotend. Basically, just below the drive gear and bearing idler setup, there is a plastic filament guide tube. On top of the hotend sits a molded plastic part that also forms the filament guide path and this part holds the magnet used for homing and rides up and down with the hotend. The problem is that the bore of that plastic part is barely larger than the raw untouched filament going in. Any deformation or larger diameter of filament will bind in this narrow bore. Since it's DEEP inside the extruder and in between the pinch gears and the hotend, it is extremely hard to access.

What  happens is that unloading filament or a retract will pull molten and deformed filament up into this narrow place and then solidify and block the hotend.

You can try poking a thin wire up through the nozzle, up through the entire hotend, and maybe the now hot wire melts that clog above the hot zone and pulls it back down clearing the path. It's important to note that the plastic bore is tapered the wrong way, meaning, that if the filament is deformed you will never in a million years force it up. The only path is back down and melting through the hotend.

Key here is methods of prevention:

#1 NEVER unload filament, only cut the filament and feed in new filament behind it.

#2 Baring that approach, ALWAYS, ALWAYS, ALWAYS feed forward for at least 10-15mm or more BEFORE removing filament. This way, no melted filament will follow back out.

In most cases of a severe jam in the Z homing device area, the ONLY method is disassembling the extruder and mechanically clearing that part since the taper of the hole is in the direction of the hotend.

On Wednesday, August 20, 2014 8:22:26 PM UTC-4, Scott Booker wrote:

[Jetguy]

FYI a complete teardown with pictures is shown here https://filenimbus.com/teardown-of-the-makerbot-5th-gen-replicator-smart-extruder-part-ii/

The place where it jams is here (Thanks to user Burn Zero in the now defunct MakerBot Operators)

https://groups.google.com/d/msg/makerbot/0YRiQB2N9z8/hBCFzjDTISwJ

[Jetguy]

Sorry, I hate it when the posting auto quotes pictures.

[Jetguy]

Also, hint, hint, the same action that causes the jams is the same reason homing fails.

I'm considering slightly drilling that plastic part to a tiny bit larger bore to eliminate this kind of jam. Don't go nuts, you don't want the filament sloppy and that would also impact using flexible filaments.

[Jon Wong]

I did the same thing, although Makerbot asked me to send it back. I still have not done so yet though.... Found this nasty thing inside. 

However, even after unclogging, it still jammed as Jetguy stated. no matter what, I get partial jams mid-print with long, flat and wide extrusion lines. 

[Jon Wong]

Just to add, I actually increased the temperature to 230 through a custom profile and it seems to be working better. I've only done 2 prints though, and I am currently printing a much larger, 4 hour print with the same setting. We shall see how it turns out! I found that when the clicking does start, I simply press down on the build plate for a few seconds and it unjams itself and happily continues. This is annoying, but I suppose might be the only solution unless it's a hardware issue.

 

[LB engg]

I used a paper clip and stuck into the top of extruder.  Make sure the extruder has cooled to room temp.  Then, squeeze the filament release tabs will inserting the unfolded paper clip into the extruder.  Push the clip until unclogged.  After I unclogged it, I reloaded filament and let it extrude for about 10 seconds.  Clogged gone without having to take extruder apart.

[flynhi808]

Ok... My new extruder just clogged without any filament change. The filament did jet stuck in the spool and I had to unstuck it. I did not unload the filament though, I just cut it at the spool. Looks like another long painful call to MBI.

[Robert Nee]

> That certainly won't fit a .4mm nozzle.......

Um, yeah, that wouldn't work. I'm pretty sure there is music wire of the right size but then again I haven't proven very trustworthy on this subject. ;)

[Samantha]

I used the B string off my electric guitar, I believe it is around 0.013" and stuck it up the nozzle to loosen up the clog. I've also been able to unclog the extruder from above by going to the filament load process and using the piece of filament to push the clog through into the heated area, where it melts down and unclogs. 

[Jeremy Rosser]

The easiest way to unclog the smart extruder is to go into the load sequence and hold the extruder on with your hand so it will not fall off. Use needle nose or just keep pressing and forcing the filiment through. That worked great for me.

[flynhi808]

Pushing the filament down did not work for me. I actually fixed the out of warranty on by taking the outer plastic case off and the jam literally fell out. I can't believe I wait on the phone for a hour then ship the extruder all the way to NY (from HI) just for them to do that!

[flynhi808]

Now I'm having over and under extrusion issues though.