Impossible to extrude with 0,25mm nozzle

[bejard 1]

Hello,

I am using Ultimaker 2 Extended with Olson block.

I am completely unable to extrude with my 0,25mm nozzle. Before it was working, just after a 0,8mm, 

The motor to feed is working well, the filament can go forward, backward without problem, but when it arrives inside the nozzle, it doesn't extrude, so the motor damage the filament.

 

I tried to push manually the filament, doesn't work

I tried cold pull ( atomic method: https://ultimaker.com/en/resources/19510-how-to-apply-atomic-method ) , almost nothing came out, it was quite normal.

I put the 0,8mm nozzle and I was able to print with this normally.

I tried to print at 190°C as I saw that 210°C could be too liquid for the 0.25 nozzle, didn't work.

I checked the temperature of the nozzle with thermal camera: the nozzle is at the good temperature, and when I apply filament outside on it, it mealts well.

- I replaced the 0,25 nozzle by another one completely new, without any filament inside, didn't work.

- I put the needle down with and without nozzle to remove some filament, didn't work

 

I don't understand the problem.

 

Do you have other methods or options to try ? What do you think ?

 

Thanks

 

 

 

Edited September 18, 2018 by bejard

[gr5 2,172]

1) Are you sure the filament makes it into the nozzle?  Many times I thought the nozzle was clogged but instead it turned out to be that the filament was getting stuck at one of many places inside the print head (top of white teflon part is most common, bottom of white teflon).  I cut the filament to a point (two cuts) everytime I feed filament into my printer.

 

2) Do you have a needle smaller than 0.25mm?  I use accupuncture needles.  I push up from below and then leave the needle in while I do a cold pull.

 

3) Try doing a cold pull on the nozzle alone.  Hold the nozzle with pliers (careful - if it gets too hot (>300C) it gets soft and you can destry it with simple pliers).  Put a drop of water on the nozzle then put it in a gas flame (gas stove is best, plumbers torch works also).  Count the seconds until water boils completely (usually 8 seconds for me) that is temp to get to 100C.  Then heat for that many seconds again.  Then remove from flame.  The nozzle cools much slower than it heats.  Now stick pla into the nozzle hard and then hold it in there with small pressure as it cools.  After about 1 minute you can pull the filament out.  If you pull too early it's okay - grab the very thin string of filament and slowly pull on it and it will cool rapidly and get strong - the string will get thicker and you need to start pulling harder and also faster and you should get every bit of filament out.  Inspect the nozzle hole with light.  It should be very visible.

 

4) Consider burning everything out of the nozzle.  I haven't done this in a few years but it seemed to help once.  Cold pulls work better because it can grab any sand or dust or other particles out of your nozzle.

[JohnInOttawa 104]

I have a 0.3 and 0.25, on a UMO and a UM3 so not the same thing.  But maybe this is related.

 

Can you share what adjustment you made to feed rate?  In my UMO, I had to almost cut it in half for the smaller nozzle.

 

John

[rebekah_harper 60]

hiya,

i never had a problem on um2+ 

whats the nozzle size in the quality settings?

i have mine set to 0.23

temp about 200-208

i don't go fast either.