# Over extrusion on Ender 3 with SKR mini E3 v1.2 and BMG clone (Bowden)

I own two Ender3 printers, a stock one and one upgraded with SKR mini E3 v1.2 and BMG clone.

I calibrated the E-steps using the filament measurement method ~415 looks correct.

The machine severely over extrudes, reducing the flow rate to ~50 % looks right. I would say it pushes out about twice as much material then it should.

I am testing this using a simple one walled cube, sliced with Cura 4.7.1.

Printing this will have the wall thickens about double and several blobbing on the side the layers are restarted.

Printing the same G-code on the stock printer works without problems.

Printing from the card or using Repetier Server does not make any difference.

• 415 is not correct, so much I can tell from my config. My Ener3 has: #define DEFAULT_AXIS_STEPS_PER_UNIT { 80, 80, 400, 93 } – Trish Nov 2 '20 at 17:40
• 93 is for the direct original extruder – sanyi Nov 2 '20 at 18:31
• correct, i expressed wrongly, I meant "not geared" as the Bondtech BMG extruder it is, such extruder has a gear reduction, hence the bigger E-steps needed – sanyi Nov 2 '20 at 20:00
• 415 should be pretty close. My BMG clone runs at 407 (with 16x microstepping and 1.8° stepper motors). 93 is obviously for the stock extruder, which the asker replaced. Make sure you have no flow rate modifiers active with M221 S100 – towe Nov 3 '20 at 6:32
• At how many microsteps have you set the TMC2209? Default should be #define E0_MICROSTEPS 16 as seen in the Configuration_adv.h. – 0scar Nov 3 '20 at 8:02