strange not smooth free extrusion and fillament stop after

Hi,
i need some help.
sudenly i found that i cant push fillament throught hotend correctly. At first it seems that i have bad fillament, but now i have it from 3 different sources and all of them doing same thing. after litle extruded distance, about 30-50mm, it starts making material "blobs" (see at foto) on strings and after litle more it leads to procedure of cleaning threaded bolt in extruder.

i tryed:
- 3 different extruders
- 2 different threaded bolts
- 2 different sets of gears for extruder
- changing of pololu for extr.
- diiferent temperature (220°C - 245°C)
- different speeds (from 30mm/s to 60mm/s)
- different tightening of screws with springs on extr. idler

Any ideas??? I think, that must by smt with nozzle. maybe wrong heating or hole is almost stuck?

---

vlastni navrh plus ve vystavbe CoreXY

Thingiverse : [www.thingiverse.com]
git: [github.com]
shop: [shop.daje.cz]
Teorie relativity:
vysvetleni 1: sahnes-li na rozpalenou panev, vteriny jsou jak hodiny. sahnes-li na rozpalenou zenu, hodiny jsou jak vteriny...
vysvetleni 2: strcis-li mi nos do zadnice, pak ja mam nos v zadku, ty mas nos v zadku, ale ja sem na tom relativne lip

Hello,

What type of filament do you use? Depending on the temperatures you use, I assume it's ABS. It is wise to upload your config.ini file for further investigation

What hot end? I have been having a vary similar sounding problem -including the appearance of the filament and think that I have found the reason.
First check is if you can push filament through the hot end (idler removed from extruder and hot end at operating temperature) with the filament pinched between finger and thumb. If it is hard to push through then it may be a plug if plastic between the metal of the hot end and the PTFE liner.
Mike.


Edit to include picture to clarify my meaning. The filament gets jammed by the plastic ring resulting from a tiny bit of ooze creaping up here. The lumpy appearance of the filament is caused by the incoming filamen rubbing and juddering - like pushing your finger across a rubberised sheet. You will find a famiar looking picture in [forums.reprap.org]


Edited 1 time(s). Last edit at 10/12/2013 02:49PM by leadinglights.

shuruoja : yes it is 3mm ABS, sorry my bad.

leadinglights : HA! it is same problem! then i must replace that teflon tube??? or place it more intouch to hot metal part?

now i start testing second hotend (0,35mm) - same type

---

vlastni navrh plus ve vystavbe CoreXY

Thingiverse : [www.thingiverse.com]
git: [github.com]
shop: [shop.daje.cz]
Teorie relativity:
vysvetleni 1: sahnes-li na rozpalenou panev, vteriny jsou jak hodiny. sahnes-li na rozpalenou zenu, hodiny jsou jak vteriny...
vysvetleni 2: strcis-li mi nos do zadnice, pak ja mam nos v zadku, ty mas nos v zadku, ale ja sem na tom relativne lip

test with differen hotend (0,35 mm nozzle) same type - same effekt

---

vlastni navrh plus ve vystavbe CoreXY

Thingiverse : [www.thingiverse.com]
git: [github.com]
shop: [shop.daje.cz]
Teorie relativity:
vysvetleni 1: sahnes-li na rozpalenou panev, vteriny jsou jak hodiny. sahnes-li na rozpalenou zenu, hodiny jsou jak vteriny...
vysvetleni 2: strcis-li mi nos do zadnice, pak ja mam nos v zadku, ty mas nos v zadku, ale ja sem na tom relativne lip

Hi raptik,

If I am right, it is only necessary that there is nowhere for a plug of plastic to lodge where it is sticky. If there is no place then there is no problem, if there is a place but it is where the plastic is molten, again no problem - and the same if there is a void where it is too cool to be sticky.

I am going to try to replace the PTFE with graphite loaded PEEK: This is nearly as slippery as PTFE but not as soft so easy to machine for a really good fit.

Mike

hmm i wonder if my succes with 0,35 nozzle will be good and is not only like "good will of hotend"... after brave or stupid test with 245°C it seems ok. on foto on the right is first attempt and left (and center) is after almost good 1m good extruded and e steps calibrated free extruded 100mm sample

---

vlastni navrh plus ve vystavbe CoreXY

Thingiverse : [www.thingiverse.com]
git: [github.com]
shop: [shop.daje.cz]
Teorie relativity:
vysvetleni 1: sahnes-li na rozpalenou panev, vteriny jsou jak hodiny. sahnes-li na rozpalenou zenu, hodiny jsou jak vteriny...
vysvetleni 2: strcis-li mi nos do zadnice, pak ja mam nos v zadku, ty mas nos v zadku, ale ja sem na tom relativne lip

HO HO HO!!!!

Maybe i got it!!!

at first i had 2 problems!
1) I don't know why or how - extruder hobbed bolt had suddenly broke one of teeth

2) badly mounted hotend after last cleaning (both 0.5mm and 0.35)

after disassembling i found too much plastic in area betwen PEEK and metal parts on booth nozzles. and now, after better mounting and cleaning i still can print for almost 5 days.

I hope that it will be fine now!!

Thanks for help to everyone

---

vlastni navrh plus ve vystavbe CoreXY

Thingiverse : [www.thingiverse.com]
git: [github.com]
shop: [shop.daje.cz]
Teorie relativity:
vysvetleni 1: sahnes-li na rozpalenou panev, vteriny jsou jak hodiny. sahnes-li na rozpalenou zenu, hodiny jsou jak vteriny...
vysvetleni 2: strcis-li mi nos do zadnice, pak ja mam nos v zadku, ty mas nos v zadku, ale ja sem na tom relativne lip