Prusa Mk3s not feeding

Hi everyone, I have a Prusa Mk3s, its had occasional issues but is generally my reliable printer. I had been printing pretty steady for a week or so and then the prints started not working…looked like under extrusion. I did 2 cold pulls and it didn’t help and now it will not feed. The autoloading spins grabs and stops.

I posted online elsewhere and some suggested the PTFE needed replacement. I picked up a new one (a capricorn tubing) replaced it and still will not feed…when i look in from the side the filament doesnt seem to line up properly…i just took it apart AGAIN and replaced with another pieces of tubing in case i cut the first a bit short. Same issue…the motor will click sometimes too…if i give steady pressure it will start to feed but when i let go no forward movement of filament.

Is this a gear or motor issue at this point? Im not sure where to go next

Hey I have an mk3s+. The tube is a good bet failing that have you actually removed the nozzle and throat? It is also possible there is a blockage somewhere. I found this thing to be fantastic, I do a pre heat for the last used filament turn off the prinetr (obviosuly no filament in the printer) and just push it down the hot end often it squirts out a bunch of junk.

I doubt it is a gear or motor issue. I would not suggest Capricorn tube for that. It is tigher and the alignment more precise. I tend to buy the pre cut. The error for it is very small and the shape it needs to be has limited room for error. Did you shape the top properly?

You should also check with Prusa they have excellent support.

Hi, thanks! its definitely in the top by the tube that the issue is arising…I bought the Capricorn tubing at 3d Canada and they said it was the same, however perhaps i should try the specific ptfe…i didn’t do anything to the top other than just stretch it slightly with the tip of an allen key…

No the top is camphered. Capricorn tube is slightly larger diameter and the hole slightly smaller. I usually buy pre cut from Prusa.

You can get the specs on the chamfer of the PTFE tubing on the Prusa website The tubing has to be the proper length and chamfered. If you remove the Bondtech side door, you should be able to slide a length of filament from the top of the extruder and pass by the stepper motor bondtech gear into the PTFE tubing below it with no friction. This would be the time to make sure the stepper bondtech gear is in alignment with the filament path and check the other bondtech gear on the the door is turning smoothly and the slot it slides into has not deformed. When you place the door back on, make sure the screw head is flush to the extruder side on the left.

Also make sure the filament end is cut clean and check to make sure the side of it was not ground down by the bondtech gear. You should always check for this anyway.

What type of filament are you using?

Edited: wrong link. I have MMU2 on my mind.

You did mention that it was printing but looking like it was under extruding. Did you change the nozzle recently or running a new sliced print than the previous? If it is neither, I am wonder if your nozzle is leaking needs to be re-adjusted to the heat block and heat break. Do a visual check that you do not have filament oozing above the nozzle, and the gap between the heat block and heat sink at the thin part of the heat break.