Cura Version
5.11.0
Operating System
Windows 11
Printer
Ultimaker 2+ Connect
Reproduction steps
- Load a STL
- Set (or notice the default) initial layer horizontal expansion
- Slice
- Preview the first layer gcode
Actual results
There is no gap between outermost perimeter and innermost brim
See first screenshot below.
Expected results
The brim should not be affected/shifted inwards as result of the use of a negative initial layer horizontal expansion.
In the screenshot provided I used 0.15 mm brim gap to make the desired result a bit more visible, 0.15 mm being the standard elephant foot compensation ("initial layer horizontal expansion") used in Orca Slicer and Prusa Slicer.
Explanation
The initial layer horizontal expansion is (mostly?) used to compensate for the widening of the first layer due to excessive squishing of the nozzle, or in other words to account for incorrect first layer height.
So, if I need such a correction, it means I already know for sure that the lines on the first layer will be wider. If no gap is left between outermost perimeter and brim to account for that (the gap being as large as the compensation itself) then by definition I also know that the brim (printed first!) and the outermost perimeter will compete for the same space on the build plate.
The issue is made more prominent by the fact that the brim lines will also be wider.
So, practical case: if the initial layer expansion is set to -0.095 mm, due to the lines being wider by said amount and lacking a gap between brim and outermost perimeter, there will be an overlap of twice that amount, 0.19 mm, which is almost half of a first layer line width!
The final result (which I can confirm myself) is that the outermost perimeter line will look worse, and the brim will stick too strongly to the perimeter and it will be more difficult to remove.
Solution proposed
I think the best would be to automatically set the brim distance equal to the amount of first layer compensation whenever the expansion is negative, the brim distance being set with sign opposite the expansion obviously.
If for some reason the user sets a positive initial layer expansion, the brim should be set automatically to zero.
The user will be of course able to input their own value which can be larger or smaller, but the default will be such that the brim and the outermost perimeter, while still adhering on their sides, will not actually compete for space, resulting in better appearance and easier removal.
Add your .zip and screenshots here ⬇️
Current result:
Expected result:
Cura Version
5.11.0
Operating System
Windows 11
Printer
Ultimaker 2+ Connect
Reproduction steps
Actual results
There is no gap between outermost perimeter and innermost brim
See first screenshot below.
Expected results
The brim should not be affected/shifted inwards as result of the use of a negative initial layer horizontal expansion.
In the screenshot provided I used 0.15 mm brim gap to make the desired result a bit more visible, 0.15 mm being the standard elephant foot compensation ("initial layer horizontal expansion") used in Orca Slicer and Prusa Slicer.
Explanation
The initial layer horizontal expansion is (mostly?) used to compensate for the widening of the first layer due to excessive squishing of the nozzle, or in other words to account for incorrect first layer height.
So, if I need such a correction, it means I already know for sure that the lines on the first layer will be wider. If no gap is left between outermost perimeter and brim to account for that (the gap being as large as the compensation itself) then by definition I also know that the brim (printed first!) and the outermost perimeter will compete for the same space on the build plate.
The issue is made more prominent by the fact that the brim lines will also be wider.
So, practical case: if the initial layer expansion is set to -0.095 mm, due to the lines being wider by said amount and lacking a gap between brim and outermost perimeter, there will be an overlap of twice that amount, 0.19 mm, which is almost half of a first layer line width!
The final result (which I can confirm myself) is that the outermost perimeter line will look worse, and the brim will stick too strongly to the perimeter and it will be more difficult to remove.
Solution proposed
I think the best would be to automatically set the brim distance equal to the amount of first layer compensation whenever the expansion is negative, the brim distance being set with sign opposite the expansion obviously.
If for some reason the user sets a positive initial layer expansion, the brim should be set automatically to zero.
The user will be of course able to input their own value which can be larger or smaller, but the default will be such that the brim and the outermost perimeter, while still adhering on their sides, will not actually compete for space, resulting in better appearance and easier removal.
Add your .zip and screenshots here ⬇️
Current result:
Expected result: