rough surface but only on one side

[david_w_faulkner15]

Using the loft tool I created a box with a smooth transition between its' sloping sides and the base

but

when printed the surface finish on two sides is awful, the other sides are perfect

In the example shown the surface with the LED's is poor, the one with the USB socket is good

I did not use any supports as the angles arent that steep and am printing in PETG @ 0.12mm layers on a new Bambu A1, the "good" sides are super smooth and very even

Other projects are super smooth all round

Any ideas please

[jeff_strater]

I don't think that this is a Fusion modeling problem.  The geometry here looks fine on both sides.  I show Gaussian Curvature and Zebra Stripe analysis:

So, I suspect that the problem is with your printer, or the slicer, or the software driving the printer, but I think the model is fine.

[david_w_faulkner15]

OK, thanks
It is strange that the other sides and also the vertical part above the slope all printed perfectly.....

[david_w_faulkner15]

I tried printing it with and without supports but the result was exactly the same

The INSIDE printed perfectly smoothly, the outside was very rough and poor

It APPEARS to be the result of the “loft” function which created the sloping sides but we cannot see why

Have attached the test piece for other suggestions

Thank you

[david_w_faulkner15]

additional pics

[jeff_strater · Accepted solution]

Not sure.  I suspect it is the holes more than the loft, but I have no proof of that.  All the 3D printer sees is triangles.  It cannot "know" that those triangles came from a loft.  I did notice that the STL you shared had a wide variation in triangle sizes on that face.  Perhaps that is confusing the slicer.  You could try exporting as mesh, and manually try to adjust the mesh so that it is more uniform, and see if that helps. 

But, I really wonder whether this is a 3D printer setting/calibration issue more than anything.

[david_w_faulkner15]

Thank you for your prompt reply.....
Strangely I have found that using higher layer sizes the problem is reduced

>From the left :   0.16, 0.12, 0.12, 0.08

[david_w_faulkner15]

Hazah.... we (my son is the brains 😁) applied the create mesh as you suggested and the result is superb and fully acceptable 

thank you

attached examples printed @ 0.12

[david_w_faulkner15]

are there any hard and fast rules or guidance as to when we should use  mesh rather than the default export .....would it be better to always use mesh if there are any complex curves etc?????