Solved Z Ribbing Caused by Extruder Calibration

I recently used the extruder calibration video to calibrate my extruder and I went from printing good to horrible after the calibration. The calibration basically told me that I was under extruding by 20mm so I changed the firmware and the I was over extruding like crazy!

I ended up changing the flow compensation in Cura down until it looked like the ribbing went away (I stopped at 60%). Of course after that I got incomplete top and bottom layers, to compensate for that I changed the nozzle diameter from 0.4 to 0.35, and the walls come out without Z Ribbing and the top and bottom are closed properly.

I will change the flow rate down in the firmware to where I am compensating in the slicer, but should I have needed to do all that after the extruder calibration? And why would I be extruding ok, but 20mm less than I should be?

 

Can't Upload any other images (reoccurring security error) but this one, but this is changing flow from 100% to 75% and nozzle diameter from 0.4mm to 0.35mm

 

there is no way you were printing nicely with a "20mm" difference in filament (over 100mm I assume?) So, you're saying you hit extrude 100 and it only moved 80mm?

so you changed your esteps from like... 750 to 950ish? If I'm understanding your 20mm
That would be wrong.

Maybe if you explain your process there will be some flaw to it

 

That is a hug flow rate difference. You shouldn't need to drop it that low. Has to be some other issues going on.

 

I know I dropped it to almost 470 E-steps when you calculate it.

 

Yes, so I increased the flow rate, so that I was printing at a solid 780 E-steps, then I got the result above with the Pi Case.
I then throttled the flow rate down until the ribbing went away, but ribbing goes away and then top and bottom layers and infill are all weak. I tried recalibrating it again, and got the same problem, if flow isn't the issue, what is causing my z ribbing?

 

After looking into that thread, I locked the Z rods in the firmware, and I was able to bring my flow back to 100%.
I adjusted the E-Steps in the firmware, and the block on the right is the current result.

The left block was being compensated in the slicer to an equivalence of 610 E-steps. (Z rods weren't locked)
The right block was not compensated for and printed at 715 E-steps. (Z rods were locked)

So should I throttle the flow rate further back or should I check the hardware itself?

 

E steps won't really cause ribbing. E steps would make the part bulge consistently or be too small on each line. You wouldn't get a ribbing from it.

It's almost always related to the Z axis drive. Either the helical couplers are off or the Z steps per mm are wrong.

 

But how would I go about testing that if the cubes are all measuring +/- 50 Microns of 200mm^3?

and this is currently the resulting difference

 

I'm assuming you've seen this for calibrating your E steps per mm?


E steps is a way of turning a rotational movement of the motor into a linear motion of the filament. When you combine this with the supplied diameter it will tell you how much filament to extrude for a given line to create a certain expected volume.

For Ribbing to be a factor in this the extruder count or layer heigh would need to "reset" to allow it to wave in and out. As I said, if your esteps were too high your part would bulge consistently. Too low and the lines would be thin. There's no way E step could result in ribbing.

Ribbing on all 4 sides of an object is caused by the Helical couplers not centering the motor to the threaded rod. This results in the rod being off axis causing it to push on the Z axis in the direction it's off. This is what causes the ribbing to align perfectly with the thread pitch.

 

Yes, this is what I used to calibrate it initially. After this video, the problem began to occur. When I get home, I'll check the couplers.

 

awful coincidental...
just sayin...

 

I'd like to see some before pictures.

 

I was printing in this yellow filament to burn through it, so I printed this really tall block to see how the z axis was doing. It wasn't prefect, but after the calibration the walls are bad.

 

Same settings? what were the layer thicknesses?

and your process.. you extruded 100mm and found it to only extrude 80mm? That's pretty dramatic. did you re-calibrate once you found you were not getting a decent print?

I'm fairly comfortable with my first impression.. but... but.. you didn't accidentally change the 2560 Z step did you?

 

Both 200 microns.

I extruded 100 mm, was under extruding by 20 mm, adjusted firmware was printing at exactly 100 mm, then the quality degraded.

Recalibrate, no, but I compensated in the slicer till quality increased, but shouldn't have had to back off as much as I did.

And no, after Mike said the Z steps might be off that was the first thing I checked.

 

No chance you reversed your maths?
certainly seems like it. you were also changing the nozzle width calculation. I've never changed that unless I actually changed the nozzle... but.. I don't know everything

 

It's definitely more severe in the white, but I'm seeing it in the yellow

It could be extruder calibration, but it's better to have it be accurate and figure out the real source of the issue.