Help with PLA filament problems

I’m having a lot of trouble getting prints to finish, so any clues, suggestions or encouragement will be greatly appreciated.

Problem 1
The filament (PLA, 180 deg, 50 deg) is now stuck in the extruder (.35). On this day the first print stopped extruding after about 10 mins. So I stopped the print, pulled out the filament (with difficulty), cleaned the knurled gear and pushed in a fresh filament end. I was able to manually extrude so I started the print again. This time it ran for about 5 mins then stopped extruding. I tried to pull out the filament but it is stuck. I heated it to 210 and tried to pull it out with pliers (even leveraging it against the frame) but it is stuck. The only plan I have now is to remove the extruder and then try to remove the nozzle and soak it all in acetone. Has anyone else had this problem or have other suggestions?

Problem 2
Sometimes the printer stops extruding because the filament spool gets stuck. I the have to try and unroll enough to get started again and then every 15 mins have to manually unroll until it’s done. This is very annoying for a long print. I don’t have this problem with ABS, only PLA. Is there something I can do to prevent the reel from getting stuck?

Problem 3
If a print happens to finish (rare), the last layer is very rough. I think I saw a suggestion on how to help this but can’t find it now. Any suggestions?

Thanks ,

Problem 1

It’s generally not a good idea use the same Budaschnozzle for PLA and ABS. When printing with PLA, the left over ABS will clog the nozzle.

I have separate Extruders for ABS and PLA.

PLA requires that the Budaschnozzle be cooled. Without a fan blowing on the cooling fins, the PLA will creep up the Nozzle and clog it.

In my opinion, the Dual Fan ducts are not totally effective, although they will help with the problem. This is because the air is split between the two channels and the fan is not always on (as it needs to be whenever the Nozzle is hot).

I use this fan duct:

It mounts on the left side, and notice that it is thinner so that it doesn’t bang into the left side of the printer.

I have it wired to the 2nd Extruder fan connection and the Marlin firmware modified so that the fan comes on automatically at 50 deg Celsius.

Problem 2

What brand filament are you using? I’ve never had a roll of Lulzbot filament get stuck but have had the problem with some other brands.

Make sure your Idler Springs on the Extruder are tight enough. For PLA, I’ve had to really tighten mine.

Problem 3

I use a 0.4 Extrusion Width for the Top Infill (all solid infills, actually). This produces a pretty smooth finish. The Triffid Hunter guide recommends using a 0.5 width.



Thank you for the fast and detailed response.
I will try using separate extruders - I already have 2 of them & it sounds like a good idea.
I have a fan duct that I removed just for the reason you said about it hitting the side. I will try the new duct you suggested.

I’m using all Lulzbot filaments and I tighten the springs down pretty tight. The filament just gets hung up in the reel. When it stops extruding, I have to pull on the filament firmly to get it to unroll.

I plan to try the new Top Infill.

Thanks again,


If you’ll be using a separate extruder for PLA, then you might also want to put plumbers tape on the nozzle threads.

Even with a cooling fan, the PLA will still leak out of the nozzle and the heater block.

I used recommendations 1 and 3 here:

It is easier to do this on a fresh hot end that hasn’t had any plastic pushed through it so that you don’t have to heat it up first in order to disassemble it. Don’t forget to loosen the set screw on the heater block :wink: and be gentle on the thermistor and resistor wires.

Also, if you will be switching complete Extruder assemblies, then don’t forget that each Extruder will have its own E-Steps. I just keep track of mine on paper and then dial them in when I switch Extruders. You won’t need to do this if you just plan to switch the Budaschnozzles.

I wonder if you got a badly wound reel of filament? I don’t think it’s common because it hasn’t yet happened on any of the Lulzbot reels I’ve used.


Thanks again, Kenny.
These are all very helpful tips.
I think you may be right about the reel being wound funny. I’m going to cut off a long piece and rewind it.
I’ll let you know how I fare.


I’ve had some heat creep of PLA coming up from top of the heater block. I’ve probably didn’t put enough of teflon tape on the threaded extension, when disassembling the Buda last time.
So I managed to take everything apart by heating up to 160c …everything but the heater block. It is somewhat stuck on the threaded extension.
Let’s say I manage to take the heater block off of it. Then I plan to use this instruction-
…in the second part it shows how to wrap the tape best.

So If anyone can confirm if I am going about it the right way. And also if I could soak the threaded extension and the heater block in acetone, will it melt off the PLA? So that I don’t have to spend much time cleaning it…


Did you loosen the set screw on the heater block? If you loosened the set screw and it still won’t come off you could soak them in acetone but just make sure you remove the thermistor and the heat resistor otherwise you could damage them.

Yes I’ve taken out the set screw at the start.

The previous layers of Teflon tape are I suppose still there, so that’s why it’s hard to take it apart.
But how did it manage to leak out even though I had it teflon coated on assembly…guess it needs a fan for the fins as well.