issue First Layer Concentric Smoothing

[oneearthtech 0]

Hi Team, 

I have a feature request/bug fix relating to the way Cura handles the first layer.

Feature Names "Initial Layer Polygon Smoothing"

Goals:

- Create as simple and smooth initially first layer with as little travels as possible

- Gradually Smooth the outer wall Geometry  into a circle.

- Remove horizontal gaps between layers where Geometry is to "Sharp"

Geometry Type Works best with geometry like circles, stars, ovals, squares without any holes. 

Problem:
When using Concentric on the first layer, and having Connect Top and Bottom Polygons selected Cura produces a "Non Stop Tool Path" which spiralizes from the inside out leaving a single layer line between each loop. 

Cura then "Closes" the loop and fills in this gap on the inward pass. 

This works very well in most cases, however some more complex geometries tend to have issues. The current work around is to adjust the initial layer with % until a suitable tool path geometry is created. This takes alot of trial an error. 

We have already made a custom change to the version we are using so that Cura spiralis from the outside in, then out again. This saves a travel move from the outer wall to the center.

Here is the change we reverted:
https://github.com/Ultimaker/Cura/issues/5033

 

The main issue now is when Non Standard Geometry is used. As shown below. 

 

Here is a close up that shows sections where a "Sharpe angle" is created which inevitably leaves small gaps in the first layer. 

       

 

Ideally cura would "smooth" the outer geometry gradually to eventually become a rounded edge square, rectangle, or ideally a circle in the center. 

Allowing the initial layer to overlap horizontally slightly by roughly 5-20% may help to provide a smoother tool path and may help to close up the gaps. The space between the layers as it spiralizes back out would need to be no larger than 80% of the layer width.

For example. If the layer width is 2.5mm than the space left between the lines would be 2mm

It wont work perfectly for every geometry, but for most it might.  Below are two geometry types sketches that might help to explain what I'm trying to achieve. The star seems to be the worst and might not actually need this setting but with the correct amount of smoothing it might help. 


                     

 

Edited July 31, 2023 by oneearthtech

[Dustin 130]

@oneearthtech Its really best to report this on github to ensure the dev team sees this. 

[oneearthtech 0]

Hi Dustin, 

OK no problem, I have added this:

https://github.com/Ultimaker/Cura/issues/16336