Poor STEP conversion in Bambu Studio?

AdamTM · February 19, 2024, 3:00pm

I am importing a model in STEP format into Bambu Studio. Bambu Studio then obviously converts this into a trianglular mesh. The quality of conversion, however, for this particular model is not good enough.

I also exported the highest resolution STL that the CAD program (NX) allows and this comes out much better in Bambu:

The facets you see are very visible also on the print.

When slicing the STEP, it almost exclusively generates G1 paths, instead of G3’s from the high res STL.

Switching wall generation to Arachne makes it slightly better in the horizontal direction, but obviously not in the vertical direction:

Either way, the wall generation is not the issue here anyhow.

My question is, is there any way of improving the import of STEP files into Bambu Studio? I hate working with STL’s so I want to avoid it if possible.

Pengu · February 19, 2024, 3:37pm

I believe this is really to do with your CAD software? I made a funnel in SolidWorks and exported it as a STEP AP214 and I’m not getting any meshing you have.

The weird drooping seen when the model is sliced appears to just be a visual thing in Bambu Studio, as when you start zooming in (for me at least), it goes away.

This is my settings for STEP Export in SolidWorks
Step Export Settings

AdamTM · February 19, 2024, 4:09pm

No, the step model and CAD software is fine. In fact, the high res STL is generated off of the very step model.

The model you have is much simpler (without revolved splines). I have had no issues with simpler models.

I don’t find a way of uploading the step model here if you want to try it. Is it possible?

Aerocats · February 19, 2024, 4:10pm

I have the same issues when I import highly curved surfaces in the step format and also have to resort to using high res STL.

Pengu · February 19, 2024, 4:11pm

As far as I am aware, you can’t upload models here. You can upload it onto MakerWorld if you would like and link it to me. I will take a look then.

Pengu · February 19, 2024, 4:12pm

This is very odd. From my understanding the STEP file should hold more information than the STL file does, even if high res. But I’ll see what i can figure out.

Aerocats · February 19, 2024, 4:13pm

I had seen this awhile back:

github.com/bambulab/BambuStudio

Imported STEP curves are not always converted to smooth curves in Bambu Studio (lack of precision)

opened 11:34AM - 19 Mar 23 UTC

DzzD

bug backend

**First, being able to use STEP files is great !! but...** When importing a S…TEP file, curves are converted to chained faces. Sometime this conversion lack of precision (not enought faces), this result in face visible in the Bambu Lab studio but also on the printed part depending on the "Quality=>Precision=>Resolution setting" wich convert back chained faces to arcs when slicing. A workaround is to increase "Quality=>Precision=>Resolution setting" a bit, but it would be better to improve STEP usage. **Two solutions :** 1 - dont convert STEP curves to chained faces and use STEP curves for slicing (probably the hardest to implement). 2 - or when converting STEP in chained faces curves use more faces. Below, a picture of an imported STEP file with two curves, the small one is ok, the big one show faces that will also appear in printed object : CAD softwar (Fusion360), smooth curves : ![image](https://user-images.githubusercontent.com/12198339/226172339-2403dc4f-fc4b-47b1-b224-166faed14d88.png) Bambu Studio, small curve ok, big curve show faces : ![image](https://user-images.githubusercontent.com/12198339/226170998-a1cb90a4-2f3e-449e-af0f-22926f04ecfe.png) Printed object, small curve ok, big curve show faces : ![image](https://user-images.githubusercontent.com/12198339/226172331-86828209-a0e4-4aa7-888b-4346a65aa594.png) **Finally :** With Fusion 360 exporting STL in high quality give better result than exporting STEP file which is too bad :(

AdamTM · February 19, 2024, 4:19pm

Ok, so I exported a new STEP file from initial STEP file in CAD and then when I import the new one in Bambu Studio it looks much better, so there might have been an issue with the CAD.

I’ll dig into setting more as I want to figure out what the first problem was.

SimEyeSee · February 19, 2024, 4:34pm

There was another post about this recently.

It seems like it is a conversion bug in the slicer. Sometimes, the STEP file is better quality while other times a high res STL is better.

In some cases, like in my post below, there is a significant defect in the conversion.

SimEyeSee · May 4, 2024, 5:09am

I was printing a part I made and found a defect in the STEP conversion in OrceSlicer. The defect isn’t as bad as in the post I linked to in the post above, so it is not that noticeable when sliced. I made a high resolution STL in Fusion by right-clicking the component and selecting Save As Mesh. I made a custom resolution which is similar to high, but a little better.

The one on the right is the STEP. It makes the curve smoother at the bottom part, but has some dents on the corner at the top part.