Filament jamming

Edit: I measured the thermistors resistance @ 25°C and it it about 96kOhm which seems fine to me. Than i measured the temperature with an infrared thermometer @25°C which was accurate. But @215°C nozzle temp i just measured ~190°C and @230°C about 205°C.
I need to say that i never tested the "real" temperature but this looks like an very large offset.
The heated bed is fine: 60°C is set and i measured 57.7°C (with glass surface on top)

Temp bump to 230° (PLA) didnt helped

Hey there,

before i describe the problem, i will give you a bit info about the printer: I built my own i3 style printer with an E3D v6 all metal hot end (good quality clone), an mks gen 1.4 with tmc2130 and an full metal frame. I printed more than a thousand hours, with different materials and without such an problem. I'm using Nema 17 1.7A 17HS4401 for all axis and the motors are fairly new (about 100 hours of printing time).

The problem:
In every damn mid print, or after a few minutes (staying hot) the filament jams inside the nozzle/heatbreak. This occours after a few successful prints and 2 days non usage. I can easily pull out the filament,cut it off, push it inside again and it will work for a bit. The most successful print was yesterday. It was 1/2 benchy. I use always quality filament with a very good diameter tolerance.

What i tried:
- changed the heatbreak (to be honest i tried three different and new full metal heatbreaks)
- changed the nozzle
- changed the heatblock
- changed the bowden coupler on each side
- changed the ptfe tube
- cleaned the extruder gear and checked all screws
- checked the filament diameter
- tried fresh PLA (215/60) and fresh PETG (230/80)
- turned off linear advance
- turned off stealthchop for the extruder
- changed the noctua 40x20mm fan with another fresh noctua and than with the stock fan
- recalibrated the extruder (drifted off by about 4mm)
- checked slic3r and cura settings
- checked the driver status via M122 if anything is shown unusual - negative

Settings:
Print speed: 60-70mm/s
travel speed: 180mm/s
retraction: 1.9mm
retraction speed: 35mm/s
fan for pla: 70-85
fan for petg: 10-25

I really dont know what i can do else, i assembled and disassembled the hotend more than 10 times now and checked that the nozzle and heatbreak alignment is fine. I hope somebody can help me to sort this out. Sorry if i missed anything.

Edited 5 time(s). Last edit at 06/14/2018 07:09AM by Lyrex.

Does the extruder chew a divot into the filament? If so increase the pinch roller pressure.
Try reducing retraction length. Direct extruders don't usually need much.
Is the extruder fan running at full speed, all the time? It should be...

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

1. The extruder pressure is very high, i checked this today
2. Its a bowden so 1.9 mm for PLA or 2.9 mm for petg is not that high right? I print with this settings from the beginning
3. Yes the hotend cooling fan is directly wired to 12V and is doing his job...

I changed the thermistor to be sure this is not the problem and testing another benchy right now..

So: PETG is working okay now, but the PLA doesnt... Still getting jams

I changed the heatbreak to a heatbreak with PTFE inlay. I can print PLA now again but in a realy bad quality, there is too much friction but i dont know where exactly

Quote
Lyrex
1. The extruder pressure is very high, i checked this today
2. Its a bowden so 1.9 mm for PLA or 2.9 mm for petg is not that high right? I print with this settings from the beginning
3. Yes the hotend cooling fan is directly wired to 12V and is doing his job...

I changed the thermistor to be sure this is not the problem and testing another benchy right now..

I use 0.8mm retraction distance for my PETG, higher values cause jamming for me aswell. Retraction speed is 25mm. Maybe that helps, turning off ironing helped me aswell.