Weird ringing/Ghosting on cylindrical prints

[KJKJhetheman 2]

Hi all,

 

I am attempting to print a cylindrical object that has numbers and tick marks engraved around the circumference; however, whenever I am done printing I get these vertical lines along the circumference of the print as well (not the z seam). It also appears as if the numbers are having a weird ghosting, or aura effect that appears around them. It wasn't so noticeable on my first print, and I thought it might have been poor resolution since the details were so small, but when I increased the size, the effects got drastically worse. 

 

I've attached some images to illustrate what I  mean by the ghosting/aura and the vertical lines. If you look closely at the bigger font pictures, you'll notice that the numbers seem to "extend and fade" away from themselves in the surrounding print and that's what I'm referring to as "aura". I also included the z seam off to the side in one of the pictures so I could show that's NOT the vertical line that I'm concerned about. 

 

Any help or suggestions would be great. I am thinking about inverting them and having them be extruding rather than engraved.

 

A bit of additional information: I am using Cura 5.6.0, the designs were made using Onshape.

 

KJ mod is the bigger print one while part studio is the smaller print one.

KJ MOD - Insert.stl Part Studio 1 - Insert.stl

[gr5 2,177]

Ghosting is indeed a common name for what you see.  "ringing" is also.  Last night I actually read some papers about the many ways to reduce ghosting (by like 99% reduction).

 

What kind of printer are you using?

 

If you are using an Ultimaker S3/S5/S7, make sure you are *not* using the engineering profiles and also make sure you have accel control and jerk control enabled.

 

Beyond that initial advice, I need to know what kind of printer you have.  Ghosting is a complicated topic.  It is caused by vibrations in the print head.  When you print those indentations, the head moves a tiny amount, but also sharp 90 degrees.  The head rings/vibrates.  Typically around 50Hz (50 times per second) but it could be anywhere from 20Hz to 500Hz depending on the printer.

 

For many printers that have belts, it helps to tighten the belts a lot (not applicable to UM3/UM5/UM7 which has belt tighteners hidden in the blocks).  When you pluck a belt it should be above 400Hz in pitch.  You can test this with a guitar tuner app on your phone.  I have a video on youtube showing how to do this.

 

It also can help to lower acceleration, jerk, and max speed.  Or lower the weight of your print head.

 

some people put an accelerometer on the print head, determine the harmonic frequencies and then you can adjust speed, jerk, acceleration to perfectly counter the vibration.  Here is a video I happend to watch last night that shows a massive exaggeration of the problem by slowing it down by 50X and increasing the distance of vibration by about 10,000X:

https://www.youtube.com/watch?v=gzBhTrHv0-c

 

In the video, the problem is so exaggerated that you might think it has nothing to do with your ghosting.  But it's the same exact problem from an engineer's perspective.

 

Klipper firmware, found on many 3d printers has these anti-ghosting (aka input shaping) features built in.

 

 

[gr5 2,177]

It looks like you have an S5.  Make sure that the belts are all equally tight (top and bottom half).  Sometimes a belt slips a tooth and half is tight and the other half is loose.

 

Make sure you aren't using engineering profiles.  Make sure accel and jerk control are on.

 

A quick fix is to drop the speed to around 20mm/sec when you get to that part of the print using a feature called "mesh modifiers".  Google "mesh modifiers cura" and read about that feature or watch a youtube video.  I'd probalby drop the acceleration to around 1000 and the jerk to around 5 all at the same time.  If you can characterize the ringing and determine the frequency, I can help you with the ideal amount of acceleration and jerk to counter the ringing 90%.  You do this by printing a cube, then measure the distance between waves with a ruler/micrometer and knowing the print speed you can calculate the frequency.  Then you want the exact same speed increase in the first half of the period of the waves as the second half.  This will counteract the ringing.

[KJKJhetheman 2]

OK, that helps a lot actually! I am using the S5 and I was using the engineering profile. Is there any reason for why the engineering profile does that? Do you think I should try it without using the engineering profile first, and if the problem persist to try doing the acceleration and jerk modifications, or do you suggest that I do them both simultaneously?

[Dustin 130]

https://support.ultimaker.com/s/article/1667411132905
This might help.

[gr5 2,177]

11 hours ago, KJKJhetheman said:

Do you think I should try it without using the engineering profile first,

 yes, definitely.  engineering profile turns off jerk and acceleration control.  I'm pretty sure the primary purpose of jerk and acceleration control is to reduce ringing.  I can't think of another reason for those.

 

Some people want accurate parts and don't care about how they look visually.  For that you want engineering mode.  Engineering mode assumes you don't care about ringing as it's too small to measure with a micrometer, yet it is visible to the eye because of the way tiny tiny tiny changes in surface slope reflect different areas of the ceiling (including lights in the ceiling) and show up extremely visible (especially on dark filaments).

 

I love engineering mode for 99% of the stuff I do but sometimes you want to do letters or something just like you are doing.  For that you don't want engineering profiles.

 

The accuracy of your "ruler" won't be affected by not using engineering mode.  Engineering profiles are more to do with the accuracy of the diameter of the part.  The accuracy of the thickness of cuboid parts.  Things like that.

[KJKJhetheman 2]

On 1/13/2024 at 12:37 AM, gr5 said:

 yes, definitely.  engineering profile turns off jerk and acceleration control.  I'm pretty sure the primary purpose of jerk and acceleration control is to reduce ringing.  I can't think of another reason for those.

 

Some people want accurate parts and don't care about how they look visually.  For that you want engineering mode.  Engineering mode assumes you don't care about ringing as it's too small to measure with a micrometer, yet it is visible to the eye because of the way tiny tiny tiny changes in surface slope reflect different areas of the ceiling (including lights in the ceiling) and show up extremely visible (especially on dark filaments).

 

I love engineering mode for 99% of the stuff I do but sometimes you want to do letters or something just like you are doing.  For that you don't want engineering profiles.

 

The accuracy of your "ruler" won't be affected by not using engineering mode.  Engineering profiles are more to do with the accuracy of the diameter of the part.  The accuracy of the thickness of cuboid parts.  Things like that.

 

Thanks, This helped a lot. I went and used the balanced profiles and it came out great and everything fit together just fine still. I was using the engineering because I incorrectly thought that the preciseness it was referring to included the the surface details and the dimensions. Thanks for such a speedy reply and sorry for taking so long to confirm that as a solution; the print didn't finish during the work day and then the holiday and a snow day delayed me from coming in to see the results. 

Thank you once again!

On 1/12/2024 at 1:23 PM, Dustin said:

https://support.ultimaker.com/s/article/1667411132905
This might help.

 

This was actually extremely helpful to have a visual representation of what the profiles prioritized. Thanks a lot!