Filament Not Loading  

RE: Filament Not Loading

1. You hear clicking. -> Extruder is working and trying to push the filament down 🙂 
2. You did a cold pull, so the filament is not connected to the filament in the nozzle (anymore). 

My suggestion/approach: 
1. Heat the nozzle up (LCD -> settings > temp > nozzle . Choose temp according type of filament PLA/PETG
2. Remove the nozzle. hold the block with a wrench and unscrew it. DO NOT BURN yourself. Just lay it aside for later. 
3. Heat the nozzle up more (up to 240-260) and wait a bit. 
4. Load filament and help the extruder pushing it down and with some luck it will flow out of the block. If not let the temp on. and try again after 5-10 minutes. 
5. If this does not work, then the PTFE tube is clogged and we have to switch to plan B (more work, nice chance to get to know your extruder). 
Let me know if you need plan B 

RE: Filament Not Loading

Eef - are you thinking of the MK3 case?  The MK4 nozzle has metal all the way up.  I don't think I'd try to heat up the block without the nozzle in place for the MK4.  Wouldn't this just cause melting of the surrounding parts?

RE: Filament Not Loading

I used some woodfill PLA with the 0.4mm nozzle, even though I knew I should have used at least a 0.5mm nozzle. The nozzle got clogged. I tried to unclog it for a while, and I ended up tossing it. I'm not going to spend hours trying to salvage a $20 part.

RE: Filament Not Loading

Posted by: @mike-b-3

thinking of the MK3 case?  

Yep. sorry, I do not know enough about the MK4. So please correct me if I am wrong with this: 
Take the nozzle out (this is the one?)
Use a heater and try to get it unclogged (DO NOT BURN YOURSELF OR THE HOUSE)
Maybe you are lucky and get it unclogged or otherwise replace it (as @fabnavigator says) 

RE: Filament Not Loading

Yes - many people have talked about using a torch to heat up the nozzle and unclog it.  Might be the answer in this case...

RE: Filament Not Loading

Just to pass on a lesson learned.  I've unclogged these nozzles with a heat gun and a torch numerous times. The jams usually occur just above the threaded area at the spot where at the  external diameter necks down (heat break). This is where you apply the heat.  Also I always remove the nozzle or nozzle adapter from the printer, to prevent damaging printer parts. 

But here's the thing, if your jammed filament runs the entire length of the guide tube and you direct heat high on the assembly, the filament at top could adhere to the inside surface of the guide tube.  I know because I've done it, and once this happens its much more difficult to clean it out.  

For removing a  plug from a nozzle adapter,  I use a metal rod ground down to pass through the guide tube. To do this successfully I remove the nozzle assembly from heat block,  heat the adapter at the bottom and push your rod completely thought the hole at the bottom.  Do not pull it back out the top or you will deposit melted filament along the withdrawal path.  and again this bad.

I also agree that this process is annoying, but since I use hardened nozzles exclusively and these suckers cost nearly $60.00 each. I'm willing to put the time in. 

Good luck

RE: Filament Not Loading

I have a similar problem: I used wooden PLA on my new MK4, and it clogged. Cold pull didn't work.

Working with the support center on line, I removed the hotend, and while hanging out I pushed PLA inside and it worked - PLA was purging out.

However, when I assembled it back, when PLA was loaded, I heard the nocking sounds, and PLA was not being purged. 

I ordered new MK4 nozzle brasses, yet I hope I can save time and recover this one.

A side question about cold pull: I used to do cold pulls with my Prusa Mini. Can I do the same with the MK4? i.e:

Open the door (to allow free force push) Heat to 250, cool down while pushing PLA, pull it up at 90 degrees?

Somehow I think the automated cold pull is not strong enough to pull. I also think no need to wait to 35 degrees...

It's risky printing any filled filament with a 0.4mm nozzle, wood and cork filled really need at least 0.6mm, 0.8mm is better ...

So far I have managed to clear all nextruder clogs (They're not frequent) by opening the nextruder, heating to a little above the printing temperature of the jammed filament and manually pushing some scrap PLA down through the nozzle - a good use for the waste ends unloaded as a spool finishes - keep pushing down until the filament is extruding freely then whip it out as quickly as you can.  I generally close the nextruder and load and purge PLA again, conventionally this time but in most cases it should be OK to skip this and carry on as usual.

Cheerio,

RE: Filament Not Loading

Posted by: @diem

It's risky printing any filled filament with a 0.4mm nozzle, wood and cork filled really need at least 0.6mm, 0.8mm is better ...

So far I have managed to clear all nextruder clogs (They're not frequent) by opening the nextruder, heating to a little above the printing temperature of the jammed filament and manually pushing some scrap PLA down through the nozzle - a good use for the waste ends unloaded as a spool finishes - keep pushing down until the filament is extruding freely then whip it out as quickly as you can.  I generally close the nextruder and load and purge PLA again, conventionally this time but in most cases it should be OK to skip this and carry on as usual.

Cheerio,

Yes - I made a mistake printing PLA wood with 0.4 - now I pay for this mistake...

About the process of pushing the PLA down the nozzle: I need to open the side door, right? to allow free path for the PLA I push from above?

Anything else I need to do? 

The MK4 is new (2 months), so I have zero maintenance knowledge.

RE: Filament Not Loading

I need to open the side door, right? to allow free path for the PLA I push from above?

Yes, in this case it's easier to push it down from the side.

I have zero maintenance knowledge.

https://help.prusa3d.com/article/regular-printer-maintenance-mk4_419000

Cheerio,

RE: Filament Not Loading

Back to my unloading filament: I printed wood PLA with 0.4 nozzle., it got clogged. My bad.

When I took put the hotend and heated it in the free air, PLA was purged out. After re-assembling, PLA can't be loaded., and of course not being purged. 

Could it be some material was stuck between the gears and the nozzle upper part? 

Could it be the nozzle is now clean but something else prevents from the new PLA to be pushed down?

RE: Filament Not Loading

You can rule out the nozzle by trying another, if you have one.

RE: Filament Not Loading

I ordered new ones. Waiting for shipment. Any other way to look between the gear and the nozzle top?

Posted by: @fabnavigator

You can rule out the nozzle by trying another, if you have one.

RE: Filament Not Loading

I changed the hot tip.  I started out with the idler gear bolts flush.  The filament did not load.  I went loser by 1/4 turns until filament loaded.  I ran a part which failed do to not sticking.  I have never had this issue before the change.  I am working on it.

RE: Filament Not Loading

I slowly loosened the idler gear tension until filament loaded.  I am successfully running.  I am still unsure of the adjustment.  I have a MK3S+ where I do not have an issue.  I have a Mini  and find that it is very difficult to hit the idler gear tension.