Extruder Run Current

General Discussion
1

Basic Information:

Printer Model: Anycubic Kobra
MCU / Printerboard: SKR 3 EZ
Host / SBC: Pi4
klippy.log

I have a Kobra (standard) that I installed and SKR 3 EZ on. If I set run current under the Extruder, the stepper will not successfully turn. If I uncomment run current, it will turn no issues, but then I’m faced with heat creep through the stepper and causing extrusion issues. 0.7 is the correct current for the stepper, but I’m at a lost as to why it won’t turn when set. The other steppers are working no issues at .4 current. The extruder is stock, a titan clone. 3:1 gear ratio.

klippy.log (3.4 MB)

2

Update, tried a different stepper and a stepper driver. Still having issues and I’m at a complete lost, anyone have any suggestions?

3

Hello @zeshi !

0.4A for the movement steppers is quite low. Prepare for skipping.
You go better with 0.7A with those.

For the extruder 0.7A should be sufficient with the gear.

This is more an issue with heat brake cooling and over extensive retracting.

Also keep in mind that the TMC2209 drivers need proper cooling.

4

I do have the SKR in an enclosure with an 80mm Noctua fan for cooling. The extruder even at .7A continues to do the same thing, will not extrude at all.

5

Switched out the pancake stepper (22mm) with a 38mm and have 0 issues with extrusion. The moment I put the 22mm stepper, it will not produce enough torque to extrude. The stock Anycubic board uses a TMC2208 vs the EZ2209 I’m currently using. That’s the only discernable difference I can see between the two set ups. Would there be a reason to have different settings of some sort with the EZ2209 to accomplish the same results!?!?

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