Extrusion lines coming out bumpy

Hello! Im having an issue with the extrusion lines not coming out flat, but bumpy.

My setup is:
E3D Titan + E3D V6
No name stepper motor
No name 12V Ramps with TMC2208 drivers on all axes
Quality 12mm hardened steel rods with No name ball bearings. LM12UU.

My thoughts on causes of this:
1. Stepper motor is pulsing; some kind of interference or current related issue in stepper driver.
2. Stepper motor is somehow faulty.
3. Infill under the surface causing the bumps.
4. Nozzle is dragging
5. Overextrusion(E-steps set to E3D recommended 418.5stps/mm)
6. Some rough motion on the axes, maybe the ball bearings are so bad they are causing small vibrations while moving.





Would really appreciate some help in this matter. What and how to test.

... this "bumps" could be oszillating extrusion speed/volume ... or maybe simply the threads beneath -- look in your 1st image on the right side, the "bumps" on crossing threads ...

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Viktor
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Indeed I can see the bumps on the infill lines when they cross each other. But at closer consideration the spacing between those bumps doesn’t match the bumps on the flat surfaces. The bumps on the flat surfaces are closer together.

I have read another thread where a user had some other issue with extrusion.
He said

Quote

Had a eureka moment. I had a similar problem with my large CNC servo mill when I got noise on the encoder wiring. My hot end wiring was tightly bundled with the stepper wires in a cable rap. It seemed possible that the 40W hot end resistor wiring could be inducing micro steps on the stepper as the Ramps board continually pulses the resistor (PID) to keep it at the right temperature.

Separated wiring and problem was solved.

My wiring to the carriage is also tightly bundled together. Might run separate motor wires just to test if interference could be the issue.

Edited 2 time(s). Last edit at 11/03/2019 02:29PM by Hatmpatn.

Looks worse in one direction than the other.
Check there is no binding in bearings, or play. Make sure the extruder is square to the bed (or it can catch in one direction) Make sure the drive belts are horizontal (or they can try and tip over the extruder). Ensure the extruder is tight to the cariage.
Fan airflow can afect the printing in certain directions.


IMHO, Your temperature looks high.

Thank you! Solid input. I will test it all tomorrow.

I think I might be on to something. X axis feels fine when I move the carriage but when I move the bed on Y-axis the feeling is uneven. When I removed the Y-motor the bed movement felt completely smooth. However, the motor itself did not. Took the motor apart and there was a lot of play in the front bearing and also the front section of the rotor had been grinding on the casing walls. Will replace the bearing tomorrow and I’ll let you know how it went.

Switched out the motor for a brand new motor.
However, it strangely enough didn't solve the issue. But it does now moves smoothly when I push it, which is nice.
I put my hand on the bed while the printer is printing the surfaces. It vibrates like crazy. Disconnected the Y-motor while printing and the vibrations disappeared. The X-axis has the same motor and stepper driver and it doesn't vibrate. The only difference is the weight of the axes, where the Y is heavier.
Ive set the TMC2208 to deliver 1,1A and the X 1,0A. Maybe it is set too high. I will try tomorrow to disconnect the pulley from the Y-axis while printing surfaces and see if the vibrations stops.

Do NOT disconnect a motor while it's running, this will most probably kill your stepper driver!

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http://www.marinusdebeer.nl/

I used to have a similar issue. For me, the cause was that the filament was "pulsing" out of the extruder. Try decreasing the current on your extruder stepper driver.