Mk8 extruder blocks

[JerryVienna]

Hello,

I have a black acrylic I3 pro B. I was able to print but suddenly the extruder had a problem and transports the filament unreliable. I replaced the nozzle and checked everything. I discovered that the teflon part is only half the size of the throat, so I exchanged the throat with a new one, with fitting teflon part.
Now i cant push the filament through the extruder to the nozzle. However, it fits through all parts if I disassemble everything. It seems the filament cant pass from the extruder part into the throat. If I losen the screws it passes through, if I fasten them again the filament cant be moved in either way.

Btw, i checked voltage, use the third nozzle, the gear is ok, the spring is supported with two washers.

I have no problem idea what to do next. Any hints?

[Newopint95]

It sounds like something is out of alignment or the teflon tube is getting pinched when you put the hot end together. You could try to reassemble the hot end with the metal clean out rod inside the teflon tube to keep things in line?

[JerryVienna]

Hi Newopint95,

I tried your suggestion, problem is I can not screw the fan back on if the metal clean out rod is in the extruder, so yes it seems there is something out of alignment, but I have not found why.
I will investigate more in the weekend.

Thank you!

[Hermie]

I see this is an old post, but the problem of clunking still exists. I used the clean out rod to align my extruder when I had the same problem, now it feed without clunking, so my problem was alignment, binding the filament.

[Saige Marvin]

The Mk8 style of the hot end has been around for a while (2007) and is one of the simplest to use, but also one of the weakest when it comes to thermal cycling. An essay writer shared with me the problem with the design is that the brass tube used as a heat break doesn't have anything holding it in place other than friction.