@Phaedrux Thank you for saving the day

I went ahead and did everything you recommended, ran a new PID tune, and re-calibrated my extruder at the lower recommended feed rate.

The difference is night and day. I'm still getting some issues where Cura has dropped the feed for cooling but it is a massive improvement.

I bumped the minimum speed up from 10 to 20mm/s and that seemed to be the final tipping point. I'm not sure why that would make such a large difference though, unless its just preventing Cura from throttling the extrusion speed?

I might check later if changing firmware compatibility and gcode flavor to reprap would change Cura's behavior at those low speeds.

As an additional odd note:
When I first installed the bondtech extruder the main gear turned with different amounts of backlash. Rotating it by hand it would tighten up slightly during part of its rotation then loosen and have a bit of backlash during other parts of its rotation. To see if it was a pinion gear spacing issue I tried moving the pinion further away from the stepper motor face but it didn't change. I also checked the bearings throughout but they were in good shape.

The file import tool didn't like the cura profile file type so I changed it to .txt

DOZER_PLA.txt

I varied coasting and pressure advance for different tests but the base profile is with no coasting.

Config: config.g

Test using modified mini gcode: 8MMCYL_0.2mm_PLA_MINI_15m.gcode

Test from Cura: CYLT6.gcode

Heaters are PID tuned. I'm not confident about the thermistor values. The bed uses a keenovo heater with built in 100k and the hotend is standard E3D parts.

Should the E3D thermistor be changed to these (T100000 B4725 C7.06e-8) and the bed stay with the default settings?

Hello, I recently finished building my second printer and I'm experiencing terribly inconsistent extrusion. I've been trying tips on fixing bowden extrusion issues but so far no luck.

The printer will alternate between under extrusion to massive over extrusion from layer to layer on small features. But is also pretty bad in general. I also sliced the same retraction test above in PrusaSlicer with the mini profile and matching jerk, acceleration, speed settings and it was about the same. It will be string free until the first blob forms then its terrible.

As a sanity check I also did a vase mode print to check if the hotend couldn't keep up. Other than cooling issues it was fine up to 90mm/s which is much faster than I'm printing at the moment.

Printer Details:
CoreXY with a bondtech bmg, ~400mm E3D bowden tube, and a E3D threaded heatsink V6 setup

Troubleshooting So Far:

• Pressure advance (high and low)
• XYZE Jerk/ acceleration/ speed (high and low)
• Checked bowden system for excess resistance
• Cleaned and adjusted bmg gear spacing
• Different bowden collet clip thicknesses
• Different E microsteps and current
• Different coast and retraction settings
• Hotend and bed temperatures don't vary much

One odd thing is that even with coasting, alternating layers will flow a bunch of material as it prints the last part of the layer.

I'm at a loss and would appreciate any help.

@Phaedrux

I did some more testing and also found that it will go into alarm mode if the probe is not vertical like it would be on the printer. If I hold it vertical it starts up fine. Sideways or inverted it goes straight into alarm mode.

I don't think my other BLTouch is this picky.

@Kolbi
At the moment nothing else is plugged in. I tried plugging everything in individually instead of in larger grouped connectors and it is working.

I also found the issue. I accidentally grabbed a 5 pin dupont housing for initial tests instead of a 4 pin so instead of Heater3 I was connecting to E3step but the wiring still looked right to me

Thank you both, glad nothing on the board was fried by my goof up

@Kolbi
The wiring matches the diagram you attached. The connectors seem to be a reasonable firm fit on the header pins. I'll remove the dupont housings and check the individual connections.

@Phaedrux
It only alarms out sometimes. It does do the initial deploy retract that happens at power on. It does not respond to M401 / M402 or M280 commands.

I'll try to get it to startup and go to an alarm state and reset it.