Hole Compensation/Contour Compensation Issue

[alexisa9]

I have recently come across an issue which I don’t believe I had in older versions of bambu studio.

The issue revolves around both hole compensation and contour compensation causing inset lines around layers where the compensation is being applied causing visual and functional defects.

Hole Compensation on (0.15mm)

Contour Compensation on (0.15mm)

Even more concerning is it also appears that when both hole and contour compensation is turned on, it doubles the compensation. As you can see in the images.
Both hole and contour compensation on (0.15mm)

Both hole and contour compensation off

I don’t believe it should be acting like this and never noticed it in earlier versions of bambu studio and certainly didn’t notice it in the prints. The insets align with the holes in the model.
The effect is consistent across all machines so it obviously has to do with how bambu studio is processing the models.
The loaded file is also an STL but consistent with STEP Files too.

Apart from adjusting the model directly, are there any other solutions. Has any one else noticed this issue?

Thanks!

[Olias]

Thanks for posting clear examples. This is very helpful. You’re examples do show a distinct artifact. Can we ask you to upload the model in question? I ask because we have seen ample examples of where the STL file experiences mathematical purterbations in the mesh itself when some options are applied. This is most obvious when scaling a model. What you may want to try out is to scale your model to let’s say 95% and 105% of size and reslicing. If the artifacts change, this is an indication that the slicer’s algorithm is adding these artifacts. A possible remedy is to open the model into another STL editor and resaving it. You could use the native Windows 10 3D Builder if you have already loaded it before April 2024(it has been since removed from the Microsoft store). Or you can use TinkerCAD, Meshmaker, FreeCAD or Fusion360.

Alternatively, for diagnostic purposes, you can use the “Simplify Model” function in the slicer itself to change the number of vertices. The Slicer uses Windows engine for this purpose which is what’s also under the hood of 3D Builder, so don’t bother with one if the other didn’t work.

Warning note: This will reduce the resolution of your STL but will be useful as a diagnostic tool if the artifacts can be shown to change.

Another alternative is if you have access to the original CAD, try exporting it as a STEP file which has more accuracy.

[alexisa9]

Thanks for the reply!

I tested changing the scale, simplifying the model and using a step file but the same issue remains. It should also be noted the outside of the model does not have the defect but the inside does. So this issue must only occur on the inside of models. For some reason it’s resizing correctly on the outside but pushing sections in on the inside.

I tried a new file with a similar shape and hole positioning and the error whilst still occuring now seems different. The shapes are also all made in fusion360, exporting as step, 3mf or stl (binary) all get the same issue)

I’ve attached the new test file to check.
Body1.3mf (20.3 KB)

[Olias]

Thanks for uploading the 3MF. This allowed me to directly interact with the model and do closer examination.

This is a real head scratcher. I can confirm your findings and that this is a bug in the slicer and also confirm it is NOT in the model. I haven’t yet tried to print it as I have a multi-hour print going on right now but I want to confirm what I see in the slicer in the real world later on today. I’ll post a follow up.

One question though: Did you actually test-print this model and did these artifacts manifest themselves in the real world?

I can say this. The artifact is directly related to the top edge of the hole when 0.15 compensation is turned on. It does not matter whether it’s X-Y contour or X-Y hole. Both scenarios produce the artifact at about the 65.5mm height regardless of layer height. I can also confirm that when sliced, the layer height is not disturbed in the slicer but it’s clearly there. In this example, I cut the model height to see if the artifact would change, it did not affect it, only enabling compensation created the artifact.

With Compensation enabled. You can clearly see that the slicer exhibits a gap in between the layers. Again, until I can print a copy, I can’t confirm that this isn’t simply a video rendering error that won’t show up in the model.

With Compensation disabled.

Note that the slicer does not actually change the layer height but you can make out the spacing in the layer height view.

One other observation. This appears to occur only with the nozzle making a full circuit around the model. When I cut it horizontally along the X/Y plane and shortened the model, the artifact remained. However, when I further cut the model in the Z-axis, the artifact disappeared. Very puzzling but this could provide a workaround. It will create an interior wall along the cut but will not affect the model strength providing you don’t disturb the pieces after they are cut and also make an assembly of them.

Here’s what I mean.

Model with artifact cut along the horizontal. The artifact is very visible.

Now cut the model in the Z-axis.

You can see the seams but the model is intact and the artifact is gone.

But as you can see, there is now an extra interior wall.

[Olias]

I ran some tests and can confirm that this truly a slicer bug.

1. Test #1 - Actual print using the cut sample:

• Result, same artifact shows up in the real world print.
  
  

2. Test #2 - Cut the model in the center.

• Result: Artifact does not show up but this creates a bulky seam that has to then be dealt with.

But!

3. Test #3 - Using the same profile, I created a similar model in CAD independent of the STL file in use here. I exported it using both STEP ver 242 and 203.

• Result: Both created similar artifacts.
  
  

Conclusion: Slicer Bug Confirmed!!!

[alexisa9]

Thanks for testing that for me.

I think it may have to do with how the slicer is interpreting holes.
Because technically the inner wall of the shape is a hole, but the hole in the wall is also considered a hole. So I’m guessing that may be some of the issue and why splitting the model in the z axis removes the issue, because the split part is no longer considered a hole with another hole inside it.

What I don’t understand though is why the outer wall has no inset applied and why a contour adjustment would also add an additional offset within the inner wall of the shape on top of the hole offset compensation.

I do remember I experienced this artifect with another print a few months back but thought it was just an individual model bug (it was a different cylindrical shape though) and it generally caused a print failure.
I also found that tilting the model a few degrees removes the inset from the top of the hole in the model, however it then generates artifacting in other areas.

It’s a pretty major bug that I’m surprised nobody else has seemed to have recognised before (to be fair I’ve only experienced it three times now). In the mean time I guess I’ll need to try and manually adjust offsets in cad but it’s not ideal to have different versions of a model for different materials.

I was considering trying the new thermal shrinkage setting in the latest bambu studio release however the problem I have is I still need to offset inner and outer surfaces.

Printing a cube 20mm cube with a 3mm hollow wall (so inner hollow should measure 14mm) in PET-CF on a Bambu Carbon X1C, the outer wall is 20.1 and the inner wall is 13.7. So there will always need to be different offsets for outer walls and inner holes.

Also what is the best way to notify bambu of this issue?

[MikeTheCuteCat]

Hi Alexisa9 &Olias,

I’m happy to discover this post as I’ve been having this same issue since I bought a Bambu A1 printer this spring (only difference is that I’m using Orca, but same thing happened with I tried Bambu Studio). I’ve read several posts around the web but none provided a solution and I’ve experienced all the same issues you both have explained in great details.

Maybe add added clue would be that I’m also having the extra wall when slicing for the Bambu A1, Bambu A1 mini and Creality Ender S1 Pro BUT the artifact disappears when slicing for the Bambu P1S and X1C (this in Orca slicer).

Hopefully this could help find a solution faster to this issue.

Wishing you a Happy New Year !

[sak11]

Anything new regarding this issue? I have parts that has tolerated holes and outer dimensions and I can only gain the required accuracy by using the compensation settings; however I am also suffering from the same issue as the OP described in first post.

[Olias]

Welcome to the community.

It’s just us fellow hobbyists here. Bambu does not regularly read these topics so if you were expecting a response, forget it.

This issue is clearly a bug as stated earlier in the thread so until Bambu feels this warrants their time, you can rest assured it will not get addressed.

You could submit a ticket through their support website and keep your figures crossed.

Good luck.