Eliminating Ringing

ringing on vertical corner

Summary: Rotate your model and decrease the acceleration to reduce ringing.

I have noticed that the vertical corners of the UM Robot print are a bit rough. This is called ringing. From what I have read, this is a result of the abrupt change between the X and Y drive mechanisms. The inertia of the print head causes some vibrations that result in a little bit of inaccuracy at the corners. Slowing print speed and decreasing acceleration can help. But simply rotating the model 45 degrees will orient the corners so that both the X and Y drives are moving at the same time and there is no abrupt change from one axis to the other. Let's rotate the model and see what happens.

model rotated in Cura

To test this, I opened the Ultimaker Robot model in Cura and rotated it 45 degrees. Then I printed at 220°C with the normal quality quickprint setting. I chose the normal quality setting because the ringing was more pronounced at that setting.

45° print on right

The corners of the rotated model were slightly better, but the ringing was still evident. Let's try adjusting the acceleration. Acceleration is adjusted directly on the UM2 by going to Maintenance > Advanced > Movement Settings. I reduced the acceleration from 3000 to 1000. Then I printed the Robot facing forward again at normal quality so we can see the effect of acceleration only. Total print time went from 42 minutes to 52 minutes.

angled print vs. reduced acceleration

The ringing is less evident than with the rotated model. Both printing on an angle and reducing acceleration seemed to have helped. Can we do even better if we print on an angle AND use the reduced acceleration setting? I loaded the rotated model from the SD card and left the acceleration set to 1000.

reduced acceleration vs. angled print with reduced acceleration

Using both settings did help. The ringing was least evident on the last print. Some of the overhangs seemed to have printed better as well. Although some signs of under extrusion popped up again. Each change made a slight improvement to the ringing problem. You can still see a little unevenness in the corners, but not much. I'm not going to mess with the print speed because I already know the ringing issue is practically eliminated when printing in the high quality setting (which prints slower).

standard, rotated, decelerated, rotated & decelerated

It's hard to see the slight improvements in the photos. The first print looks much better than it actually is. The two in the middle are pretty similar. But I think you can tell that the last print is the best.